The present paper describes the use of a readily synthesized, environmentally benign, reusable and nontoxic
iron based nanocomposite i.e iron(II) bipyridine grafted to graphitic carbon nitride (Fe(bpy)3/npg-
C3N4) as a photocatalyst, molecular oxygen as an oxidant and a household white LED as a light emitting
source for the oxidative coupling of benzylamines under mild reaction conditions. The developed heterogenized
homogeneous photocatalyst showed excellent activity with the added benefits of facile recovery
and efficient recycling ability without any significant loss in catalytic activity.
A [Fe(bpy)3]2+ grafted graphitic carbon nitride hybrid for visible light assi...Pawan Kumar
The document summarizes the development of an iron(II) bipyridine complex grafted to nanoporous graphitic carbon nitride (Fe(bpy)3/npg-C3N4) as a photocatalyst for the oxidative coupling of benzylamines using molecular oxygen and visible light. The photocatalyst showed excellent activity and the benefits of easy recovery and recycling without loss of activity. Characterization methods like SEM, TEM, XRD and XPS confirmed the immobilization of the iron complex on the carbon nitride support without affecting its structure. The photocatalyst exhibited enhanced surface area and visible light absorption compared to the individual components. It represents an efficient and reusable system for the oxidative reaction under
Photo-induced reduction of CO2 using a magnetically separable Ru-CoPc@TiO2@Si...Pawan Kumar
An efficient photo-induced reduction of CO2 using magnetically separable Ru-CoPc@TiO2@SiO2@Fe3O4
as a heterogeneous catalyst in which CoPc and Ru(bpy)2phene complexes were attached to a solid
support via covalent attachment under visible light is described. The as-synthesized catalyst was characterized
by a series of techniques including FTIR, UV-Vis, XRD, SEM, TEM, etc. and subsequently tested for
the photocatalytic reduction of carbon dioxide using triethylamine as a sacrificial donor and water as a
reaction medium. The developed photocatalyst exhibited a significantly higher catalytic activity to give a
methanol yield of 2570.78 μmol per g cat after 48 h.
C3N5: A Low Bandgap Semiconductor Containing an Azo-Linked Carbon Nitride Fra...Pawan Kumar
Modification of carbon nitride based polymeric 2D materials for tailoring their optical, electronic and chemical properties for various applications has gained significant interest. The present report demonstrates the synthesis of a novel modified carbon nitride framework with a remarkable 3:5 C:N stoichiometry (C3N5) and an electronic bandgap of 1.76 eV, by thermal deammoniation of the melem hydrazine precursor. Characterization revealed that in the C3N5 polymer, two s-heptazine units are bridged together with azo linkage, which constitutes an entirely new and different bonding fashion from g-C3N4 where three heptazine units are linked together with tertiary nitrogen. Extended conjugation due to overlap of azo nitrogens and increased electron density on heptazine nucleus due to the aromatic π network of heptazine units lead to an upward shift of the valence band maximum resulting in bandgap reduction
C3N5: A Low Bandgap Semiconductor Containing an Azo-Linked Carbon Nitride Fra...Pawan Kumar
This document describes the synthesis and characterization of a novel carbon nitride framework called C3N5. C3N5 has a 3:5 carbon to nitrogen stoichiometry and is synthesized by thermal deammoniation of melem hydrazine. Characterization reveals that in the C3N5 polymer, two s-heptazine units are bridged together with an azo linkage. This azo linkage extends the π-conjugated network and lowers the electronic bandgap to 1.76 eV compared to 2.7 eV for g-C3N4. Due to its lower bandgap and electron-rich character, C3N5 shows improved performance for applications in solar cells, photocatalysis
A closed loop ammonium salt system for recovery of high-purity lead tetroxide...Ary Assuncao
This document describes a closed-loop hydrometallurgical process for recovering high-purity lead tetroxide from spent lead-acid battery paste. The process involves leaching the paste with a mixed solution of ammonium acetate, acetic acid, and hydrogen peroxide. The leachate is then reacted with ammonium carbonate to precipitate lead carbonate. Impurities are removed during leaching and precipitation. The regenerated leachate is recycled for the next leaching. Lead carbonate is calcined to produce lead tetroxide with low impurity levels meeting industry standards. This process allows for reagent recirculation and production of a high value lead recovery product.
Metal-organic hybrid: Photoreduction of CO2 using graphitic carbon nitride su...Pawan Kumar
A novel heteroleptic iridium complex supported on graphitic carbon nitride was synthesized and used
for photoreduction of carbon dioxide under visible light irradiation. The methanol yield obtained after
24 h irradiation was 9934 mmol g1cat (TON 1241 with respect to Ir) by using triethylamine (TEA) as a
sacrificial donor, which was significantly higher as compared to the semiconductor carbon nitride
145 mmol g1cat under identical conditions. The presence of triethylamine was found to be vital for the
higher methanol yield. After the reaction, the photocatalyst could easily be recovered and reused for
subsequent six runs without significant loss in photo activity.
Metal-organic hybrid: Photoreduction of CO2 using graphitic carbon nitride su...Pawan Kumar
A novel heteroleptic iridium complex supported on graphitic carbon nitride was synthesized and used for photoreduction of carbon dioxide under visible light irradiation. The methanol yield obtained after 24 h irradiation was 9934 μmol g−1cat (TON 1241 with respect to Ir) by using triethylamine (TEA) as a sacrificial donor, which was significantly higher as compared to the semiconductor carbon nitride 145 μmol g−1cat under identical conditions. The presence of triethylamine was found to be vital for the higher methanol yield. After the reaction, the photocatalyst could easily be recovered and reused for subsequent six runs without significant loss in photo activity.
Metal-organic hybrid: Photoreduction of CO2 using graphitic carbon nitride su...Pawan Kumar
A novel heteroleptic iridium complex supported on graphitic carbon nitride was synthesized and used
for photoreduction of carbon dioxide under visible light irradiation. The methanol yield obtained after
24 h irradiation was 9934 mmol g1cat (TON 1241 with respect to Ir) by using triethylamine (TEA) as a
sacrificial donor, which was significantly higher as compared to the semiconductor carbon nitride
145 mmol g1cat under identical conditions. The presence of triethylamine was found to be vital for the
higher methanol yield. After the reaction, the photocatalyst could easily be recovered and reused for
subsequent six runs without significant loss in photo activity.
A [Fe(bpy)3]2+ grafted graphitic carbon nitride hybrid for visible light assi...Pawan Kumar
The document summarizes the development of an iron(II) bipyridine complex grafted to nanoporous graphitic carbon nitride (Fe(bpy)3/npg-C3N4) as a photocatalyst for the oxidative coupling of benzylamines using molecular oxygen and visible light. The photocatalyst showed excellent activity and the benefits of easy recovery and recycling without loss of activity. Characterization methods like SEM, TEM, XRD and XPS confirmed the immobilization of the iron complex on the carbon nitride support without affecting its structure. The photocatalyst exhibited enhanced surface area and visible light absorption compared to the individual components. It represents an efficient and reusable system for the oxidative reaction under
Photo-induced reduction of CO2 using a magnetically separable Ru-CoPc@TiO2@Si...Pawan Kumar
An efficient photo-induced reduction of CO2 using magnetically separable Ru-CoPc@TiO2@SiO2@Fe3O4
as a heterogeneous catalyst in which CoPc and Ru(bpy)2phene complexes were attached to a solid
support via covalent attachment under visible light is described. The as-synthesized catalyst was characterized
by a series of techniques including FTIR, UV-Vis, XRD, SEM, TEM, etc. and subsequently tested for
the photocatalytic reduction of carbon dioxide using triethylamine as a sacrificial donor and water as a
reaction medium. The developed photocatalyst exhibited a significantly higher catalytic activity to give a
methanol yield of 2570.78 μmol per g cat after 48 h.
C3N5: A Low Bandgap Semiconductor Containing an Azo-Linked Carbon Nitride Fra...Pawan Kumar
Modification of carbon nitride based polymeric 2D materials for tailoring their optical, electronic and chemical properties for various applications has gained significant interest. The present report demonstrates the synthesis of a novel modified carbon nitride framework with a remarkable 3:5 C:N stoichiometry (C3N5) and an electronic bandgap of 1.76 eV, by thermal deammoniation of the melem hydrazine precursor. Characterization revealed that in the C3N5 polymer, two s-heptazine units are bridged together with azo linkage, which constitutes an entirely new and different bonding fashion from g-C3N4 where three heptazine units are linked together with tertiary nitrogen. Extended conjugation due to overlap of azo nitrogens and increased electron density on heptazine nucleus due to the aromatic π network of heptazine units lead to an upward shift of the valence band maximum resulting in bandgap reduction
C3N5: A Low Bandgap Semiconductor Containing an Azo-Linked Carbon Nitride Fra...Pawan Kumar
This document describes the synthesis and characterization of a novel carbon nitride framework called C3N5. C3N5 has a 3:5 carbon to nitrogen stoichiometry and is synthesized by thermal deammoniation of melem hydrazine. Characterization reveals that in the C3N5 polymer, two s-heptazine units are bridged together with an azo linkage. This azo linkage extends the π-conjugated network and lowers the electronic bandgap to 1.76 eV compared to 2.7 eV for g-C3N4. Due to its lower bandgap and electron-rich character, C3N5 shows improved performance for applications in solar cells, photocatalysis
A closed loop ammonium salt system for recovery of high-purity lead tetroxide...Ary Assuncao
This document describes a closed-loop hydrometallurgical process for recovering high-purity lead tetroxide from spent lead-acid battery paste. The process involves leaching the paste with a mixed solution of ammonium acetate, acetic acid, and hydrogen peroxide. The leachate is then reacted with ammonium carbonate to precipitate lead carbonate. Impurities are removed during leaching and precipitation. The regenerated leachate is recycled for the next leaching. Lead carbonate is calcined to produce lead tetroxide with low impurity levels meeting industry standards. This process allows for reagent recirculation and production of a high value lead recovery product.
Metal-organic hybrid: Photoreduction of CO2 using graphitic carbon nitride su...Pawan Kumar
A novel heteroleptic iridium complex supported on graphitic carbon nitride was synthesized and used
for photoreduction of carbon dioxide under visible light irradiation. The methanol yield obtained after
24 h irradiation was 9934 mmol g1cat (TON 1241 with respect to Ir) by using triethylamine (TEA) as a
sacrificial donor, which was significantly higher as compared to the semiconductor carbon nitride
145 mmol g1cat under identical conditions. The presence of triethylamine was found to be vital for the
higher methanol yield. After the reaction, the photocatalyst could easily be recovered and reused for
subsequent six runs without significant loss in photo activity.
Metal-organic hybrid: Photoreduction of CO2 using graphitic carbon nitride su...Pawan Kumar
A novel heteroleptic iridium complex supported on graphitic carbon nitride was synthesized and used for photoreduction of carbon dioxide under visible light irradiation. The methanol yield obtained after 24 h irradiation was 9934 μmol g−1cat (TON 1241 with respect to Ir) by using triethylamine (TEA) as a sacrificial donor, which was significantly higher as compared to the semiconductor carbon nitride 145 μmol g−1cat under identical conditions. The presence of triethylamine was found to be vital for the higher methanol yield. After the reaction, the photocatalyst could easily be recovered and reused for subsequent six runs without significant loss in photo activity.
Metal-organic hybrid: Photoreduction of CO2 using graphitic carbon nitride su...Pawan Kumar
A novel heteroleptic iridium complex supported on graphitic carbon nitride was synthesized and used
for photoreduction of carbon dioxide under visible light irradiation. The methanol yield obtained after
24 h irradiation was 9934 mmol g1cat (TON 1241 with respect to Ir) by using triethylamine (TEA) as a
sacrificial donor, which was significantly higher as compared to the semiconductor carbon nitride
145 mmol g1cat under identical conditions. The presence of triethylamine was found to be vital for the
higher methanol yield. After the reaction, the photocatalyst could easily be recovered and reused for
subsequent six runs without significant loss in photo activity.
Synthesis and characterization of mixed ligand complexes of some metals with ...Taghreed Al-Noor
This document summarizes the synthesis and characterization of mixed ligand metal complexes containing nicotinamide and L-phenylalanine. The complexes were synthesized and analyzed using various techniques such as melting point, solubility, molar conductivity, UV-Vis and FT-IR spectroscopy. The complexes had the general formula [M(NA)2(phe)]Cl, where M is a divalent metal ion such as Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) or Hg(II). The study showed that L-phenylalanine acted as a bidentate ligand through its carboxylate and amine groups, while nicotinamide coordinated as
N-doped graphene quantum dots (NGQDs) catalyze the efficient electrochemical reduction of carbon dioxide into multi-carbon hydrocarbons and oxygenates such as ethylene, ethanol, and n-propanol. The NGQDs achieve high total faradaic efficiencies of up to 90% for carbon dioxide reduction, with selectivities for ethylene and ethanol conversions reaching 45%. Control experiments confirm the NGQDs are responsible for catalyzing the reaction. Compared to undoped graphene quantum dots, the NGQDs have higher activity and selectivity for producing valuable fuel and chemical products from carbon dioxide due to the presence of pyridinic nitrogen defects introduced during synthesis.
Graphene oxide immobilized copper phthalocyanine tetrasulphonamide: the first...Pawan Kumar
The first successful synthesis of DMC directly from methanol and carbon dioxide using a heterogenized
homogeneous graphene oxide immobilized copper phthalocyanine tetrasulphonamide catalyst in the
presence of N,N0-dicyclohexylcarbodiimide (DCC) as a dehydrating agent is described. The presence of a
dehydrating agent was found to be vital and in its absence the yield of DMC was found to be decreased
significantly. Under the optimized reaction conditions, the maximum yield of DMC reaches up to 13.3%.
Although the homogeneous copper phthalocyanine tetrasulphonamide catalyst provided a little higher
yield of DMC (14.2%), the facile recovery and recycling ability of the heterogeneous catalyst make the
developed method more attractive from environmental and economical viewpoints.
Carbon Nitride Grafted Cobalt Complex (Co@npg-C3N4) for Visible LightAssiste...Pawan Kumar
1) A cobalt complex was covalently grafted to nanoporous graphitic carbon nitride (npg-C3N4) via a click reaction to create a heterogeneous photocatalyst called Co@npg-C3N4.
2) Under visible light irradiation at room temperature, Co@npg-C3N4 efficiently catalyzed the direct esterification of aldehydes without the need for an external base.
3) Characterization of Co@npg-C3N4 showed the cobalt complex was successfully immobilized via click chemistry, providing a robust photocatalyst that could be easily recovered and reused without significant loss of activity.
2021 influence of basic carbon additives on the electrochemical performance ...Ary Assuncao
This study investigates the effect of carbon surface basicity on the electrochemical performance and dynamic charge acceptance of lead-carbon batteries. Five activated carbons with different pH values ranging from 9.5 to 11.1 were prepared by ammonia and hydrogen gas treatments. Cyclic voltammetry showed that the hydrogen evolution reaction activity increased with higher carbon surface basicity. Testing of lead-carbon electrodes found a correlation between carbon pH and dynamic charge acceptance, with higher pH carbons showing improved charge currents and final dynamic charge acceptance. The carbon content also affected charge currents during simulated microcycles, demonstrating that surface chemistry and amount of carbon additive both influence the electrochemical properties and performance of lead-carbon batteries.
Water-splitting photoelectrodes consisting of heterojunctions of carbon nitri...Pawan Kumar
Quinary and senary non-stoichiometric double perovskites such as Ba2Ca0.66Nb1.34-xFexO6-δ (BCNF) have been utilized for gas sensing, solid oxide fuel cells and thermochemical CO2 reduction. Herein, we examined their potential as narrow bandgap semiconductors for use in solar energy harvesting. A cobalt co-doped BCNF, Ba2Ca0.66Nb0.68Fe0.33Co0.33O6-δ (BCNFCo), exhibited an optical absorption edge at ~ 800 nm, p-type conduction and a distinct photoresponse upto 640 nm while demonstrating high thermochemical stability. A nanocomposite of BCNFCo and g-C3N4 (CN) was prepared via a facile solvent assisted exfoliation/blending approach using dichlorobenzene and glycerol at a moderate temperature. The exfoliation of g-C3N4 followed by wrapping on perovskite established an effective heterojunction between the materials for charge separation. The conjugated 2D sheets of CN enabled better charge migration resulting in increased photoelectrochemical performance. A blend composed of 40 wt% perovskite and CN performed optimally, whilst achieving a photocurrent density as high as 1.5 mA cm-2 for sunlight-driven water-splitting with a Faradaic efficiency as high as ~ 88%.
This document describes Michael Ludden's synthesis and characterization of various molybdenum complexes. Three complexes were synthesized - [CpMo(CO)3Me], [CpMo(CO)3Et], and [CpMo(CO)2(COMe)(PPh3)]. They were characterized using NMR and IR spectroscopy. The results confirmed the structures of the complexes and showed how changing ligands affects properties. Kinetic measurements of migratory insertion reactions will be taken using these complexes to understand reaction rate dependence on factors like solvent, temperature and ligand type.
The document describes a method for synthesizing NiFe2O4 nanoparticles fully anchored within a carbon network using a facile pyrolysis technique. Key points:
- NiFe2O4 nanoparticles were synthesized within a carbon network using a polyol-assisted pyrolysis method without an external carbon source.
- Characterization with SEM and TEM showed the NiFe2O4 nanoparticles were uniformly distributed and fully embedded within the carbon network.
- Electrochemical testing showed the NiFe2O4/C anode delivered a reversible capacity of 381.8 mAh/g after 100 cycles at 1C rates and 263.7 mAh/g at a high rate of 5C, demonstrating enhanced performance over bare
This dissertation defense summarizes Yongjia Li's doctoral research on the design of nanostructured catalyst materials. The defense included three parts: (1) using graphene as a catalyst support for hemin, which showed activity for toluene oxidation; (2) developing bimetallic nanocatalysts including Au-Pd porous structures for alcohol oxidation and Au-Cu nanostars for CO2 reduction; and (3) a plasmonic photocatalyst using Au/Pd-TiO2 nanocomposites for tandem benzimidazole synthesis. The research demonstrated how nanostructuring and composition influences catalytic activity, selectivity, and photon absorption efficiency.
This document describes the synthesis and characterization of a core-shell structured reduced graphene oxide wrapped magnetically separable rGO@CuZnO@Fe3O4 microspheres photocatalyst and its use for the photoreduction of carbon dioxide to methanol under visible light irradiation. The photocatalyst takes advantage of the high photocatalytic efficiency of zinc oxide, the high surface area and charge carrier mobility of reduced graphene oxide, and the magnetic properties of an iron oxide core. Experimental results showed the rGO@CuZnO@Fe3O4 photocatalyst had higher catalytic activity than other possible combinations, with a methanol yield of 2656 μmol/gcat under visible light, and could be readily recovered and
Synthesis of flower-like magnetite nanoassembly: Application in the efficient...Pawan Kumar
A facile approach for the synthesis of magnetite microspheres with flower-like morphology is reported
that proceeds via the reduction of iron(III) oxide under a hydrogen atmosphere. The ensuing magnetic
catalyst is well characterized by XRD, FE-SEM, TEM, N2 adsorption-desorption isotherm, and
Mössbauer spectroscopy and explored for a simple yet efficient transfer hydrogenation reduction of a
variety of nitroarenes to respective anilines in good to excellent yields (up to 98%) employing hydrazine
hydrate. The catalyst could be easily separated at the end of a reaction using an external magnet and
can be recycled up to 10 times without any loss in catalytic activity.
Visible light assisted reduction of nitrobenzenes using Fe(bpy)3+2/rGOnanocom...Pawan Kumar
Visible-light-induced photocatalytic reduction of aromatic nitrobenzenes to the corresponding anilinesat room temperature using reduced graphene oxide (rGO) immobilized iron(II) bipyridine complex asphotocatalyst is described. The rGO-immobilized iron catalyst exhibited superior catalytic activity thanhomogeneous iron(II) bipyridine complex and much higher than metal free rGO photocatalysts. Theheterogeneous photocatalyst was found to be robust and could easily be recovered and reused for severalruns without any significant loss in photocatalytic activity.
Photocatalytic Mechanism Control and Study of Carrier Dynamics in CdS@C3N5 Co...Pawan Kumar
We present a potential solution to the problem of extraction of photogenerated holes from CdS nanocrystals and nanowires. The nanosheet form of C3N5 is a low-band-gap (Eg = 2.03 eV), azo-linked graphenic carbon nitride framework formed by the polymerization of melem hydrazine (MHP). C3N5 nanosheets were either wrapped around CdS nanorods (NRs) following the synthesis of pristine chalcogenide or intercalated among them by an in situ synthesis protocol to form two kinds of heterostructures, CdS-MHP and CdS-MHPINS, respectively. CdS-MHP improved the photocatalytic degradation rate of 4-nitrophenol by nearly an order of magnitude in comparison to bare CdS NRs. CdS-MHP also enhanced the sunlight-driven photocatalytic activity of bare CdS NWs for the decolorization of rhodamine B (RhB) by a remarkable 300% through the improved extraction and utilization of photogenerated holes due to surface passivation. More interestingly, CdS-MHP provided reaction pathway control over RhB degradation. In the absence of scavengers, CdS-MHP degraded RhB through the N-deethylation pathway. When either hole scavenger or electron scavenger was added to the RhB solution, the photocatalytic activity of CdS-MHP remained mostly unchanged, while the degradation mechanism shifted to the chromophore cleavage (cycloreversion) pathway. We investigated the optoelectronic properties of CdS-C3N5 heterojunctions using density functional theory (DFT) simulations, finite difference time domain (FDTD) simulations, time-resolved terahertz spectroscopy (TRTS), and photoconductivity measurements. TRTS indicated high carrier mobilities >450 cm2 V–1 s–1 and carrier relaxation times >60 ps for CdS-MHP, while CdS-MHPINS exhibited much lower mobilities <150 cm2 V–1 s–1 and short carrier relaxation times <20 ps. Hysteresis in the photoconductive J–V characteristics of CdS NWs disappeared in CdS-MHP, confirming surface passivation. Dispersion-corrected DFT simulations indicated a delocalized HOMO and a LUMO localized on C3N5 in CdS-MHP. C3N5, with its extended π-conjugation and low band gap, can function as a shuttle to extract carriers and excitons in nanostructured heterojunctions, and enhance performance in optoelectronic devices. Our results demonstrate how carrier dynamics in core–shell heterostructures can be manipulated to achieve control over the reaction mechanism in photocatalysis.
Application of triple-layer remote phosphor configuration results in the colo...TELKOMNIKA JOURNAL
This study proposed the triple-layer remote phosphor (TRP) structure to enhance the color quality and the emitted luminous flux of white LEDs (WLEDs). The TRP structure consists of three different phosphor layers that are arranged as follows: the yellow YAG:Ce3+ phosphor at the bottom, the red phosphor layer CaMgSi2O6:Eu2+,Mn2+ at the top and the green Ba2Li2Si2O7:Sn2+,Mn2+ phosphor between these two ones. The aim to use the red CaMgSi2O6:Eu2+,Mn2+ phosphor is to control the red light component so that the color rendering index (CRI) could be increased. While the green Ba2Li2Si2O7:Sn2+,Mn2+ phosphor is applied to manage the green light component, leading to the rise in luminous efficacy (LE) of WLEDs. Moreover, when the concentrations of these two phosphors are raised, that of the yellow phosphor YAG:Ce3+ has to be decreased to remain the average correlated color temperatures (ACTTs) in a range from 6000 K to 8500 K. Furthermore, not only the CRI and LE but the color quality scale (CQS) is also analyzed by controlling the two green and red phosphor concentrations. The researched results show that the higher the concentration of CaMgSi2O6:Eu2+,Mn2+, the more enhancements in the CRI will be made. In contrast, when the Ba2Li2Si2O7:Sn2+,Mn2+ concentration increases, the CRI significantly decreases. Meanwhile, CQS is likely to considerably rise in a concentration range from 10% to 14% of CaMgSi2O6:Eu2+,Mn2+, regardless of the presence of Ba2Li2Si2O7:Sn2+,Mn2+ concentration. Especially, in parallel with the improvement of CRI and CQS, the LE could be also increased by more than 40% due to the decline in back-scattering lights and the green lights supplement. From these details, the results of this study are valuable references for manufacturers to achieve the goals of enhancing color quality and luminous efficiency of WLEDs.
This document discusses the use of 1,2-Bis(N’-benzoylthioureido)benzene (BBTB) as an ionophore for detecting lead cations. Experimental studies using UV-Vis spectrophotometry showed that BBTB forms a 2:1 complex with lead, indicated by a breakpoint in the absorbance versus concentration plot. Theoretical DFT studies calculated binding energies and optimized structures, confirming complex formation between BBTB and lead cations. Overall, BBTB was found to selectively bind lead cations, demonstrating its potential as a selective ionophore sensor for lead quantification.
Development of novel catalytic systems for photoreduction of CO2 to fuel and ...Pawan Kumar
This document summarizes the proposed research project on developing novel catalytic systems for the photoreduction of CO2 to fuels and chemicals. The project will focus on using transition metal complexes as photocatalysts immobilized on supporting materials like graphene oxide. Previous work has shown that ruthenium and cobalt complexes immobilized on graphene oxide are effective visible-light active catalysts for reducing CO2 to methanol. The proposed work will synthesize new graphene oxide-supported transition metal complexes and characterize their photocatalytic activity for CO2 reduction.
The document discusses photocatalytic conversion of carbon dioxide into fuels and chemicals. It describes how semiconductor-based photocatalysts like TiO2 can be used to drive the reduction of CO2 into products like methanol using solar energy. Challenges include the large band gap of most semiconductors, which limits them to using only UV light. The document explores using metal complexes immobilized on photoactive supports as an alternative, as they have visible light activity and can be tuned to favor specific products. Specific examples discussed include cobalt phthalocyanine and tin phthalocyanine immobilized on graphene oxide and mesoporous ceria, respectively, as well as heteroleptic ruthenium complexes immobilized on graphene oxide
Heterostructured nanocomposite tin phthalocyanine@mesoporous ceria (SnPc@CeO2...Pawan Kumar
Heterostructured tin phthalocyanine supported to mesoporous ceria was synthesized and used a
photocatalyst for CO2 reduction under visible light. The photoreduction CO2 activities of the
heterostructures were investigated in the presence of triethylamine as sacrificial agent. The developed
photocatalyst exhibited high catalytic activity for photoreduction of CO2 and after 24 hours of visible
light irradiation 2342 mmol g1 cat of methanol (fMeOH ¼ 0.0223 or 2.23%) and 840 mmol g1 cat of CO
(fCO ¼ 0.0026 or 0.26%) were obtained as the major reaction products. The methanol formation rate
(RMeOH) and CO formation rate (RCO) was found to be 97.5 mmol h1 g1 cat and 35.0 mmol h1 g1 cat
respectively. While under the identical experimental conditions mesoporous ceria (meso-CeO2) gave
only 316 mmol g1 cat of methanol (fMeOH ¼ 0.003 or 0.30%) and 126 mmol g1 cat CO (fCO ¼ 0.0004
or 0.04%) with product formation rate RMeOH ¼ 13.2 mmol h1 g1 cat and RCO ¼ 5.3 mmol h1 g1 cat.
Furthermore, the recovered catalyst showed consistent catalytic activity for at least five runs without any
significant loss in product yields
- Nickel (II) aminoguanidine complexes can be synthesized using either nickel chloride or nickel acetate solutions.
- The complexes only form under neutral pH conditions, and have an orange color and proposed square planar geometry.
- Traces of the complexes can be detected in solutions like Powerade using UV-visible spectroscopy, with peaks around 448-449 nm.
- The research aims to characterize these complexes as potential replacements for green energetic materials in preventing acts of terrorism.
Maiyalagan, Synthesis and electro catalytic activity of methanol oxidation on...kutty79
Template synthesis of various nitrogen containing carbon nanotubes using different nitrogen containing polymers and the variation of nitrogen
content in carbon nanotube (CNT) on the behaviour of supported Pt electrodes in the anodic oxidation of methanol in direct methanol fuel cells was
investigated. Characterizations of the as-prepared catalysts are investigated by electron microscopy and electrochemical analysis. The catalyst with
N-containing CNT as a support exhibits a higher catalytic activity than that carbon supported platinum electrode and CNT supported electrodes.
The N-containing CNT supported electrodes with 10.5% nitrogen content show a higher catalytic activity compared to other N-CNT supported
electrodes. This could be due to the existence of additional active sites on the surface of the N-containing CNT supported electrodes, which favours
better dispersion of Pt particles. Also, the strong metal-support interaction plays a major role in enhancing the catalytic activity for methanol
oxidation.
The present paper describes the use of readily synthesized, environmentally benign, reusable and non-toxic iron based nanocomposite i.e iron(II) bipyridine complex immobilized to graphitic carbon nitride (Fe(bpy)3/npg-C3N4) as photocatalyst, molecular oxygen as oxidant and house hold white LED as light emitting source for the oxidative coupling of benzylamines under mild reaction conditions. The developed heterogenized homogeneous photocatalyst showed excellent activity with the added benefits of facile recovery and efficient recycling ability without any detectable loss in activity.
Visible light driven photocatalytic oxidation of thiols to disulfides using i...Pawan Kumar
The present paper describes the synthesis of graphene oxide immobilized iron phthalocyanine (FePc) for
the photocatalytic oxidation of thiols to disulfides under alkaline free conditions. Iron phthalocyanine
tetrasulfonamide was immobilized on carboxylated graphene oxide supports via covalent attachment.
The loading of FePc on GO nanosheets was confirmed by FTIR, Raman, ICP-AES, UV-Vis and elemental
analyses. The synthesized catalyst was found to be highly efficient for the photo-oxidation of thiols to
disulfides in aqueous medium using molecular oxygen as oxidant under visible light irradiation. The
identification of photo-oxidation products and their quantitative determination was done using GC-MS.
After completion of the reaction, the catalyst was easily recovered by filtration and reused for several
runs without loss in activity and no leaching was observed during the reaction
Synthesis and characterization of mixed ligand complexes of some metals with ...Taghreed Al-Noor
This document summarizes the synthesis and characterization of mixed ligand metal complexes containing nicotinamide and L-phenylalanine. The complexes were synthesized and analyzed using various techniques such as melting point, solubility, molar conductivity, UV-Vis and FT-IR spectroscopy. The complexes had the general formula [M(NA)2(phe)]Cl, where M is a divalent metal ion such as Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) or Hg(II). The study showed that L-phenylalanine acted as a bidentate ligand through its carboxylate and amine groups, while nicotinamide coordinated as
N-doped graphene quantum dots (NGQDs) catalyze the efficient electrochemical reduction of carbon dioxide into multi-carbon hydrocarbons and oxygenates such as ethylene, ethanol, and n-propanol. The NGQDs achieve high total faradaic efficiencies of up to 90% for carbon dioxide reduction, with selectivities for ethylene and ethanol conversions reaching 45%. Control experiments confirm the NGQDs are responsible for catalyzing the reaction. Compared to undoped graphene quantum dots, the NGQDs have higher activity and selectivity for producing valuable fuel and chemical products from carbon dioxide due to the presence of pyridinic nitrogen defects introduced during synthesis.
Graphene oxide immobilized copper phthalocyanine tetrasulphonamide: the first...Pawan Kumar
The first successful synthesis of DMC directly from methanol and carbon dioxide using a heterogenized
homogeneous graphene oxide immobilized copper phthalocyanine tetrasulphonamide catalyst in the
presence of N,N0-dicyclohexylcarbodiimide (DCC) as a dehydrating agent is described. The presence of a
dehydrating agent was found to be vital and in its absence the yield of DMC was found to be decreased
significantly. Under the optimized reaction conditions, the maximum yield of DMC reaches up to 13.3%.
Although the homogeneous copper phthalocyanine tetrasulphonamide catalyst provided a little higher
yield of DMC (14.2%), the facile recovery and recycling ability of the heterogeneous catalyst make the
developed method more attractive from environmental and economical viewpoints.
Carbon Nitride Grafted Cobalt Complex (Co@npg-C3N4) for Visible LightAssiste...Pawan Kumar
1) A cobalt complex was covalently grafted to nanoporous graphitic carbon nitride (npg-C3N4) via a click reaction to create a heterogeneous photocatalyst called Co@npg-C3N4.
2) Under visible light irradiation at room temperature, Co@npg-C3N4 efficiently catalyzed the direct esterification of aldehydes without the need for an external base.
3) Characterization of Co@npg-C3N4 showed the cobalt complex was successfully immobilized via click chemistry, providing a robust photocatalyst that could be easily recovered and reused without significant loss of activity.
2021 influence of basic carbon additives on the electrochemical performance ...Ary Assuncao
This study investigates the effect of carbon surface basicity on the electrochemical performance and dynamic charge acceptance of lead-carbon batteries. Five activated carbons with different pH values ranging from 9.5 to 11.1 were prepared by ammonia and hydrogen gas treatments. Cyclic voltammetry showed that the hydrogen evolution reaction activity increased with higher carbon surface basicity. Testing of lead-carbon electrodes found a correlation between carbon pH and dynamic charge acceptance, with higher pH carbons showing improved charge currents and final dynamic charge acceptance. The carbon content also affected charge currents during simulated microcycles, demonstrating that surface chemistry and amount of carbon additive both influence the electrochemical properties and performance of lead-carbon batteries.
Water-splitting photoelectrodes consisting of heterojunctions of carbon nitri...Pawan Kumar
Quinary and senary non-stoichiometric double perovskites such as Ba2Ca0.66Nb1.34-xFexO6-δ (BCNF) have been utilized for gas sensing, solid oxide fuel cells and thermochemical CO2 reduction. Herein, we examined their potential as narrow bandgap semiconductors for use in solar energy harvesting. A cobalt co-doped BCNF, Ba2Ca0.66Nb0.68Fe0.33Co0.33O6-δ (BCNFCo), exhibited an optical absorption edge at ~ 800 nm, p-type conduction and a distinct photoresponse upto 640 nm while demonstrating high thermochemical stability. A nanocomposite of BCNFCo and g-C3N4 (CN) was prepared via a facile solvent assisted exfoliation/blending approach using dichlorobenzene and glycerol at a moderate temperature. The exfoliation of g-C3N4 followed by wrapping on perovskite established an effective heterojunction between the materials for charge separation. The conjugated 2D sheets of CN enabled better charge migration resulting in increased photoelectrochemical performance. A blend composed of 40 wt% perovskite and CN performed optimally, whilst achieving a photocurrent density as high as 1.5 mA cm-2 for sunlight-driven water-splitting with a Faradaic efficiency as high as ~ 88%.
This document describes Michael Ludden's synthesis and characterization of various molybdenum complexes. Three complexes were synthesized - [CpMo(CO)3Me], [CpMo(CO)3Et], and [CpMo(CO)2(COMe)(PPh3)]. They were characterized using NMR and IR spectroscopy. The results confirmed the structures of the complexes and showed how changing ligands affects properties. Kinetic measurements of migratory insertion reactions will be taken using these complexes to understand reaction rate dependence on factors like solvent, temperature and ligand type.
The document describes a method for synthesizing NiFe2O4 nanoparticles fully anchored within a carbon network using a facile pyrolysis technique. Key points:
- NiFe2O4 nanoparticles were synthesized within a carbon network using a polyol-assisted pyrolysis method without an external carbon source.
- Characterization with SEM and TEM showed the NiFe2O4 nanoparticles were uniformly distributed and fully embedded within the carbon network.
- Electrochemical testing showed the NiFe2O4/C anode delivered a reversible capacity of 381.8 mAh/g after 100 cycles at 1C rates and 263.7 mAh/g at a high rate of 5C, demonstrating enhanced performance over bare
This dissertation defense summarizes Yongjia Li's doctoral research on the design of nanostructured catalyst materials. The defense included three parts: (1) using graphene as a catalyst support for hemin, which showed activity for toluene oxidation; (2) developing bimetallic nanocatalysts including Au-Pd porous structures for alcohol oxidation and Au-Cu nanostars for CO2 reduction; and (3) a plasmonic photocatalyst using Au/Pd-TiO2 nanocomposites for tandem benzimidazole synthesis. The research demonstrated how nanostructuring and composition influences catalytic activity, selectivity, and photon absorption efficiency.
This document describes the synthesis and characterization of a core-shell structured reduced graphene oxide wrapped magnetically separable rGO@CuZnO@Fe3O4 microspheres photocatalyst and its use for the photoreduction of carbon dioxide to methanol under visible light irradiation. The photocatalyst takes advantage of the high photocatalytic efficiency of zinc oxide, the high surface area and charge carrier mobility of reduced graphene oxide, and the magnetic properties of an iron oxide core. Experimental results showed the rGO@CuZnO@Fe3O4 photocatalyst had higher catalytic activity than other possible combinations, with a methanol yield of 2656 μmol/gcat under visible light, and could be readily recovered and
Synthesis of flower-like magnetite nanoassembly: Application in the efficient...Pawan Kumar
A facile approach for the synthesis of magnetite microspheres with flower-like morphology is reported
that proceeds via the reduction of iron(III) oxide under a hydrogen atmosphere. The ensuing magnetic
catalyst is well characterized by XRD, FE-SEM, TEM, N2 adsorption-desorption isotherm, and
Mössbauer spectroscopy and explored for a simple yet efficient transfer hydrogenation reduction of a
variety of nitroarenes to respective anilines in good to excellent yields (up to 98%) employing hydrazine
hydrate. The catalyst could be easily separated at the end of a reaction using an external magnet and
can be recycled up to 10 times without any loss in catalytic activity.
Visible light assisted reduction of nitrobenzenes using Fe(bpy)3+2/rGOnanocom...Pawan Kumar
Visible-light-induced photocatalytic reduction of aromatic nitrobenzenes to the corresponding anilinesat room temperature using reduced graphene oxide (rGO) immobilized iron(II) bipyridine complex asphotocatalyst is described. The rGO-immobilized iron catalyst exhibited superior catalytic activity thanhomogeneous iron(II) bipyridine complex and much higher than metal free rGO photocatalysts. Theheterogeneous photocatalyst was found to be robust and could easily be recovered and reused for severalruns without any significant loss in photocatalytic activity.
Photocatalytic Mechanism Control and Study of Carrier Dynamics in CdS@C3N5 Co...Pawan Kumar
We present a potential solution to the problem of extraction of photogenerated holes from CdS nanocrystals and nanowires. The nanosheet form of C3N5 is a low-band-gap (Eg = 2.03 eV), azo-linked graphenic carbon nitride framework formed by the polymerization of melem hydrazine (MHP). C3N5 nanosheets were either wrapped around CdS nanorods (NRs) following the synthesis of pristine chalcogenide or intercalated among them by an in situ synthesis protocol to form two kinds of heterostructures, CdS-MHP and CdS-MHPINS, respectively. CdS-MHP improved the photocatalytic degradation rate of 4-nitrophenol by nearly an order of magnitude in comparison to bare CdS NRs. CdS-MHP also enhanced the sunlight-driven photocatalytic activity of bare CdS NWs for the decolorization of rhodamine B (RhB) by a remarkable 300% through the improved extraction and utilization of photogenerated holes due to surface passivation. More interestingly, CdS-MHP provided reaction pathway control over RhB degradation. In the absence of scavengers, CdS-MHP degraded RhB through the N-deethylation pathway. When either hole scavenger or electron scavenger was added to the RhB solution, the photocatalytic activity of CdS-MHP remained mostly unchanged, while the degradation mechanism shifted to the chromophore cleavage (cycloreversion) pathway. We investigated the optoelectronic properties of CdS-C3N5 heterojunctions using density functional theory (DFT) simulations, finite difference time domain (FDTD) simulations, time-resolved terahertz spectroscopy (TRTS), and photoconductivity measurements. TRTS indicated high carrier mobilities >450 cm2 V–1 s–1 and carrier relaxation times >60 ps for CdS-MHP, while CdS-MHPINS exhibited much lower mobilities <150 cm2 V–1 s–1 and short carrier relaxation times <20 ps. Hysteresis in the photoconductive J–V characteristics of CdS NWs disappeared in CdS-MHP, confirming surface passivation. Dispersion-corrected DFT simulations indicated a delocalized HOMO and a LUMO localized on C3N5 in CdS-MHP. C3N5, with its extended π-conjugation and low band gap, can function as a shuttle to extract carriers and excitons in nanostructured heterojunctions, and enhance performance in optoelectronic devices. Our results demonstrate how carrier dynamics in core–shell heterostructures can be manipulated to achieve control over the reaction mechanism in photocatalysis.
Application of triple-layer remote phosphor configuration results in the colo...TELKOMNIKA JOURNAL
This study proposed the triple-layer remote phosphor (TRP) structure to enhance the color quality and the emitted luminous flux of white LEDs (WLEDs). The TRP structure consists of three different phosphor layers that are arranged as follows: the yellow YAG:Ce3+ phosphor at the bottom, the red phosphor layer CaMgSi2O6:Eu2+,Mn2+ at the top and the green Ba2Li2Si2O7:Sn2+,Mn2+ phosphor between these two ones. The aim to use the red CaMgSi2O6:Eu2+,Mn2+ phosphor is to control the red light component so that the color rendering index (CRI) could be increased. While the green Ba2Li2Si2O7:Sn2+,Mn2+ phosphor is applied to manage the green light component, leading to the rise in luminous efficacy (LE) of WLEDs. Moreover, when the concentrations of these two phosphors are raised, that of the yellow phosphor YAG:Ce3+ has to be decreased to remain the average correlated color temperatures (ACTTs) in a range from 6000 K to 8500 K. Furthermore, not only the CRI and LE but the color quality scale (CQS) is also analyzed by controlling the two green and red phosphor concentrations. The researched results show that the higher the concentration of CaMgSi2O6:Eu2+,Mn2+, the more enhancements in the CRI will be made. In contrast, when the Ba2Li2Si2O7:Sn2+,Mn2+ concentration increases, the CRI significantly decreases. Meanwhile, CQS is likely to considerably rise in a concentration range from 10% to 14% of CaMgSi2O6:Eu2+,Mn2+, regardless of the presence of Ba2Li2Si2O7:Sn2+,Mn2+ concentration. Especially, in parallel with the improvement of CRI and CQS, the LE could be also increased by more than 40% due to the decline in back-scattering lights and the green lights supplement. From these details, the results of this study are valuable references for manufacturers to achieve the goals of enhancing color quality and luminous efficiency of WLEDs.
This document discusses the use of 1,2-Bis(N’-benzoylthioureido)benzene (BBTB) as an ionophore for detecting lead cations. Experimental studies using UV-Vis spectrophotometry showed that BBTB forms a 2:1 complex with lead, indicated by a breakpoint in the absorbance versus concentration plot. Theoretical DFT studies calculated binding energies and optimized structures, confirming complex formation between BBTB and lead cations. Overall, BBTB was found to selectively bind lead cations, demonstrating its potential as a selective ionophore sensor for lead quantification.
Development of novel catalytic systems for photoreduction of CO2 to fuel and ...Pawan Kumar
This document summarizes the proposed research project on developing novel catalytic systems for the photoreduction of CO2 to fuels and chemicals. The project will focus on using transition metal complexes as photocatalysts immobilized on supporting materials like graphene oxide. Previous work has shown that ruthenium and cobalt complexes immobilized on graphene oxide are effective visible-light active catalysts for reducing CO2 to methanol. The proposed work will synthesize new graphene oxide-supported transition metal complexes and characterize their photocatalytic activity for CO2 reduction.
The document discusses photocatalytic conversion of carbon dioxide into fuels and chemicals. It describes how semiconductor-based photocatalysts like TiO2 can be used to drive the reduction of CO2 into products like methanol using solar energy. Challenges include the large band gap of most semiconductors, which limits them to using only UV light. The document explores using metal complexes immobilized on photoactive supports as an alternative, as they have visible light activity and can be tuned to favor specific products. Specific examples discussed include cobalt phthalocyanine and tin phthalocyanine immobilized on graphene oxide and mesoporous ceria, respectively, as well as heteroleptic ruthenium complexes immobilized on graphene oxide
Heterostructured nanocomposite tin phthalocyanine@mesoporous ceria (SnPc@CeO2...Pawan Kumar
Heterostructured tin phthalocyanine supported to mesoporous ceria was synthesized and used a
photocatalyst for CO2 reduction under visible light. The photoreduction CO2 activities of the
heterostructures were investigated in the presence of triethylamine as sacrificial agent. The developed
photocatalyst exhibited high catalytic activity for photoreduction of CO2 and after 24 hours of visible
light irradiation 2342 mmol g1 cat of methanol (fMeOH ¼ 0.0223 or 2.23%) and 840 mmol g1 cat of CO
(fCO ¼ 0.0026 or 0.26%) were obtained as the major reaction products. The methanol formation rate
(RMeOH) and CO formation rate (RCO) was found to be 97.5 mmol h1 g1 cat and 35.0 mmol h1 g1 cat
respectively. While under the identical experimental conditions mesoporous ceria (meso-CeO2) gave
only 316 mmol g1 cat of methanol (fMeOH ¼ 0.003 or 0.30%) and 126 mmol g1 cat CO (fCO ¼ 0.0004
or 0.04%) with product formation rate RMeOH ¼ 13.2 mmol h1 g1 cat and RCO ¼ 5.3 mmol h1 g1 cat.
Furthermore, the recovered catalyst showed consistent catalytic activity for at least five runs without any
significant loss in product yields
- Nickel (II) aminoguanidine complexes can be synthesized using either nickel chloride or nickel acetate solutions.
- The complexes only form under neutral pH conditions, and have an orange color and proposed square planar geometry.
- Traces of the complexes can be detected in solutions like Powerade using UV-visible spectroscopy, with peaks around 448-449 nm.
- The research aims to characterize these complexes as potential replacements for green energetic materials in preventing acts of terrorism.
Maiyalagan, Synthesis and electro catalytic activity of methanol oxidation on...kutty79
Template synthesis of various nitrogen containing carbon nanotubes using different nitrogen containing polymers and the variation of nitrogen
content in carbon nanotube (CNT) on the behaviour of supported Pt electrodes in the anodic oxidation of methanol in direct methanol fuel cells was
investigated. Characterizations of the as-prepared catalysts are investigated by electron microscopy and electrochemical analysis. The catalyst with
N-containing CNT as a support exhibits a higher catalytic activity than that carbon supported platinum electrode and CNT supported electrodes.
The N-containing CNT supported electrodes with 10.5% nitrogen content show a higher catalytic activity compared to other N-CNT supported
electrodes. This could be due to the existence of additional active sites on the surface of the N-containing CNT supported electrodes, which favours
better dispersion of Pt particles. Also, the strong metal-support interaction plays a major role in enhancing the catalytic activity for methanol
oxidation.
Maiyalagan, Synthesis and electro catalytic activity of methanol oxidation on...
Similar to A [Fe(bpy)3]2+ grafted graphitic carbon nitride hybrid for visible light assisted oxidative coupling of benzylamines under mild reaction conditions
The present paper describes the use of readily synthesized, environmentally benign, reusable and non-toxic iron based nanocomposite i.e iron(II) bipyridine complex immobilized to graphitic carbon nitride (Fe(bpy)3/npg-C3N4) as photocatalyst, molecular oxygen as oxidant and house hold white LED as light emitting source for the oxidative coupling of benzylamines under mild reaction conditions. The developed heterogenized homogeneous photocatalyst showed excellent activity with the added benefits of facile recovery and efficient recycling ability without any detectable loss in activity.
Visible light driven photocatalytic oxidation of thiols to disulfides using i...Pawan Kumar
The present paper describes the synthesis of graphene oxide immobilized iron phthalocyanine (FePc) for
the photocatalytic oxidation of thiols to disulfides under alkaline free conditions. Iron phthalocyanine
tetrasulfonamide was immobilized on carboxylated graphene oxide supports via covalent attachment.
The loading of FePc on GO nanosheets was confirmed by FTIR, Raman, ICP-AES, UV-Vis and elemental
analyses. The synthesized catalyst was found to be highly efficient for the photo-oxidation of thiols to
disulfides in aqueous medium using molecular oxygen as oxidant under visible light irradiation. The
identification of photo-oxidation products and their quantitative determination was done using GC-MS.
After completion of the reaction, the catalyst was easily recovered by filtration and reused for several
runs without loss in activity and no leaching was observed during the reaction
Nickel Decorated on Phosphorous-Doped Carbon Nitride as an Efficient Photocat...Pawan Kumar
Nickel nanoparticle-decorated phosphorous-doped graphitic carbon nitride (Ni@g-PC3N4)
was synthesized and used as an efficient photoactive catalyst for the reduction of various
nitrobenzenes under visible light irradiation. Hydrazine monohydrate was used as the source
of protons and electrons for the intended reaction. The developed photocatalyst was found to be
highly active and afforded excellent product yields under mild experimental conditions. In addition,
the photocatalyst could easily be recovered and reused for several runs without any detectable
leaching during the reaction.
Photo-induced reduction of CO2 using a magnetically separable Ru-CoPc@TiO2@Si...Pawan Kumar
An efficient photo-induced reduction of CO2 using magnetically separable Ru-CoPc@TiO2@SiO2@Fe3O4
as a heterogeneous catalyst in which CoPc and Ru(bpy)2phene complexes were attached to a solid
support via covalent attachment under visible light is described. The as-synthesized catalyst was characterized
by a series of techniques including FTIR, UV-Vis, XRD, SEM, TEM, etc. and subsequently tested for
the photocatalytic reduction of carbon dioxide using triethylamine as a sacrificial donor and water as a
reaction medium. The developed photocatalyst exhibited a significantly higher catalytic activity to give a
methanol yield of 2570.78 μmol per g cat after 48 h.
A TiO2 immobilized Ru(II) polyazine complex: a visible-light active photoredo...Pawan Kumar
This document describes the development of a TiO2 immobilized Ru(II) polyazine complex photocatalyst for the oxidative cyanation of tertiary amines to a-aminonitriles. Key points:
- The photocatalyst was synthesized by grafting a ruthenium polyazine complex onto nanocrystalline TiO2.
- Under visible light irradiation, the photocatalyst efficiently catalyzed the oxidative cyanation of various tertiary amines to the corresponding a-aminonitriles in high yields using molecular oxygen as the oxidant.
- The photocatalyst could be easily recovered by simple filtration and reused for several runs with consistent activity, demonstrating its recyclability.
The DNA cleavage and antimicrobial studies of Co(II), Ni(II), Cu(II) and Zn(I...IOSR Journals
This document summarizes a study on the synthesis and characterization of Schiff base complexes of Co(II), Ni(II), Cu(II) and Zn(II) using 4-pyridinecarboxaldehyde and 4-aminopyridine. The complexes were characterized using elemental analysis, magnetic susceptibility, IR spectroscopy, XRD and SEM. The complexes showed antimicrobial activity against bacteria and fungi. The metal complexes exhibited higher antimicrobial activity than the Schiff base ligand. Gel electrophoresis studies showed the complexes were able to cleave DNA, indicating their potential as chemical nucleases.
Visible light driven photocatalytic oxidation of thiols to disulfides using i...Pawan Kumar
The present paper describes the synthesis of graphene oxide immobilized iron phthalocyanine (FePc) for the photocatalytic oxidation of thiols to disulfides under alkaline free conditions. Iron phthalocyanine tetrasulfonamide was immobilized on carboxylated graphene oxide supports via covalent attachment.
The loading of FePc on GO nanosheets was confirmed by FTIR, Raman, ICP-AES, UV-Vis and elemental analyses. The synthesized catalyst was found to be highly efficient for the photo-oxidation of thiols to
disulfides in aqueous medium using molecular oxygen as oxidant under visible light irradiation. The identification of photo-oxidation products and their quantitative determination was done using GC-MS. After completion of the reaction, the catalyst was easily recovered by filtration and reused for several runs without loss in activity and no leaching was observed during the reaction.
Organic inorganic hybrid cobalt phthalocyanine/polyaniline as efficient catal...Pawan Kumar
Organic inorganic hybrid catalyst synthesized by doping of cobalt phthalocyanine (CoPc) on
polyaniline support (CoPc/PANI) exhibited higher activity for the oxidation of various alcohols
to the corresponding carbonyl compounds in high to excellent yield using molecular oxygen as
oxidant and isobutyraldehyde as a sacrificial agent. Notably, the synthesized catalyst was found
to be truly heterogeneous in nature and could be easily recovered, recycled for several recycling
runs without loss of catalytic activity
The document summarizes research on the fabrication of iron oxide microrods (MRs) with different crystal phases through a solvothermal method and annealing processes. It was found that carbon remained in the structures when annealing at low temperature (150°C), contributing to higher dye adsorption and drug loading capabilities. The Fe3O4-C sample showed superior adsorption of cationic and anionic dyes. When applied as a drug carrier, the MRs achieved mass loading ratios of 12.9% for chemical loading and 7.8% for physical loading of tissue plasminogen activator. The magnetic structures show potential for applications in water treatment and medicine.
This document summarizes the author's research experience and Ph.D. thesis. Over six years, the author gained expertise in organometallic chemistry and catalysis. The thesis focused on studying whether cooperative participation of two metal components could enhance reaction rates, selectivity, or enable new reactions. Bimetallic catalysts incorporating palladium, ruthenium, and copper were synthesized and evaluated for reactions like C-C bond formation, carbene transfer, cyclopropanation, and allylation. The thesis contained four chapters describing the synthesis of various dinuclear complexes and studies of their catalytic properties.
Photocatalytic reduction of carbon dioxide to methanol using a ruthenium trin...Pawan Kumar
This document summarizes the photocatalytic reduction of carbon dioxide to methanol using a ruthenium trinuclear polyazine complex immobilized on graphene oxide under visible light irradiation. Specifically:
- A ruthenium complex was synthesized and immobilized on graphene oxide through complexation. This developed photocatalyst was used to reduce CO2 to methanol under visible light irradiation.
- After 48 hours of illumination, the yield of methanol was 3977.57 mmol/gcat, higher than for graphene oxide alone. The catalyst could be reused without loss of activity.
- Characterization showed the ruthenium complex was successfully immobilized on the graphene oxide support, enhancing its photocatalytic activity and enabling
BaAl1.4Si0.6O3.4N0.6:Eu 2+ green phosphors’ application for improving lumin...IJECEIAES
The molten salt synthesis (MSS) method was used to effectively prepare green phosphors BaAl1.4Si0.6O3.4N0.6:Eu 2+ (or BSON:Eu 2+ ) via one homogeneous sphere-like morphology utilizing NaNO3 in the form of the reacting agent. The phosphors produced one wide stimulation spectrum between 250 and 460 nm, as well as a significant green emission has a maximum point at 510 nm owing to the 4f 6 1 5d 7 -4f 8 ( S7/2) shifts for Eu 2+ ions. With illumination under 365 as well as 450 nm, the ideal discharge strengths for the specimen prepared utilizing melted salt would receive a boost of 17% and 13%, surpassing the specimen prepared utilizing the traditional solid-state reaction (SSR) approach. The abatement of concentration for the ions of Eu 2+ from BSON:Eu 2+ is 5 mol%. In addition, the interactivity of dipole-dipole would be the cause of said abatement. Heat abatement would be studied utilizing the formation coordinate method with abatement temperature reaching ∼200 C. Elemental mapping as well as power-dispersing X-ray spectroscopy (EDS) spectra demonstrated that the expected BaAl1.4Si0.6O3.4N0.6:Eu 2+ materials were formed.
Optical Studies of Ni and Fe Doped Tin Oxide Nanoparticles by Co-Precipitatio...IRJET Journal
This document describes a study on the synthesis and characterization of pure, nickel-doped, and iron-doped tin oxide nanoparticles. The nanoparticles were synthesized via a co-precipitation method and analyzed using various techniques. X-ray diffraction analysis showed that the nanoparticles crystallized in the tetragonal rutile structure. UV-visible spectroscopy revealed that doping reduced the optical band gap. Fourier transform infrared spectroscopy confirmed the incorporation of nickel and iron into the tin lattice. Photoluminescence spectra exhibited blue emission peaks attributed to electron transitions involving defect levels. Scanning electron microscopy images displayed nanoparticle morphology and energy-dispersive X-ray spectroscopy confirmed the presence of tin, oxygen, and dopants in the samples.
Synthesis and Characterization of Polyaniline Doped with Cu Salts and Cu Comp...ijtsrd
In this work, we have synthesized polyaniline doped with Cu II salts and coordination complexes in presence of Aniline was polymerized in presence ammonium persulphate APS . We varied the concentration of APS and also that of Cu II salts and complexes to see the effect of these on the properties of polyaniline. We investigated the effect of the dopant and ligand around Cu II ion on the morphology, crystallinity and conductivity of the resultant polyaniline. The products were characterized by UV Vis, FT IR spectroscopy, while the morphology and crystallinity were investigated by scanning electron microscopy, and X ray diffraction studies respectively. Results show that the morphology, crystallinity and conductivity of the doped polyanilines are found to be influenced by nature of ligand. Madhab Upadhyaya | Dilip K Kakati "Synthesis and Characterization of Polyaniline Doped with Cu-Salts and Cu-Complexes" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-6 | Issue-7 , December 2022, URL: https://www.ijtsrd.com/papers/ijtsrd52609.pdf Paper URL: https://www.ijtsrd.com/chemistry/other/52609/synthesis-and-characterization-of-polyaniline-doped-with-cusalts-and-cucomplexes/madhab-upadhyaya
Final Report (Graphene supported platinum nanoparticles) (1)Sridharan Thirumalai
This document is a student project report on platinum-graphene nanocomposites as electrocatalysts in PEM fuel cells. It was submitted by T.V. Sridharan to Professor Manoj Neergat at the Indian Institute of Technology, Bombay under his supervision. The report describes the synthesis of Pt/rGO nanocomposites using a modified polyol method, and their physical and electrochemical characterization. TEM analysis showed the successful deposition of platinum nanoparticles on graphene oxide sheets. Electrochemical experiments found the Pt/rGO composite had a higher effective surface area than Pt/C, but similar activity for the oxygen reduction reaction. Further research is needed to fully realize graphene's potential as
Research Inventy : International Journal of Engineering and Scienceresearchinventy
Research Inventy : International Journal of Engineering and Science is published by the group of young academic and industrial researchers with 12 Issues per year. It is an online as well as print version open access journal that provides rapid publication (monthly) of articles in all areas of the subject such as: civil, mechanical, chemical, electronic and computer engineering as well as production and information technology. The Journal welcomes the submission of manuscripts that meet the general criteria of significance and scientific excellence. Papers will be published by rapid process within 20 days after acceptance and peer review process takes only 7 days. All articles published in Research Inventy will be peer-reviewed.
Research Inventy : International Journal of Engineering and Scienceresearchinventy
Research Inventy : International Journal of Engineering and Science is published by the group of young academic and industrial researchers with 12 Issues per year. It is an online as well as print version open access journal that provides rapid publication (monthly) of articles in all areas of the subject such as: civil, mechanical, chemical, electronic and computer engineering as well as production and information technology. The Journal welcomes the submission of manuscripts that meet the general criteria of significance and scientific excellence. Papers will be published by rapid process within 20 days after acceptance and peer review process takes only 7 days. All articles published in Research Inventy will be peer-reviewed.
Preparation and Physical Characterization of Sulfur/Carbon Black Composite Ca...IRJET Journal
The document summarizes research on the preparation and characterization of a sulfur/carbon black composite cathode material for lithium-sulfur batteries. Key points:
1) A sulfur/carbon black (S/CB) composite was prepared via ball milling and heat treatment. Carbon black was added to improve conductivity and accommodate sulfur volume expansion.
2) XRD analysis showed the composite has the crystalline structure of elemental sulfur, while SEM images revealed uniform distribution of sulfur within the carbon black.
3) FTIR and Raman spectroscopy confirmed the presence of both sulfur and carbon black in the composite.
4) The composite cathode material is expected to enhance electrochemical performance in lithium-sulfur batteries due to
Synthesis, Spectroscopic Studies and Antibacterial Activity of Novel Schiff B...IRJET Journal
The document describes the synthesis and characterization of novel Schiff base metal complexes derived from condensation of 5-bromosalicylaldehyde, 4,5-dichloro-o-phenylenediamine, and pentane-2,4-dione. Specifically, copper(II), nickel(II), and oxovanadium(IV) complexes were synthesized and characterized using analytical, spectral, electrochemical, and antimicrobial methods. The complexes were found to have general formula [M(L)]X where M is the metal and L is the tetradentate Schiff base ligand. Spectroscopic data indicated the ligand coordinates through the hydroxyl oxygen and azomethine nitrogen. The metal complexes
This document summarizes research on using various catalysts to promote the dehydrogenation of cyclohexane to produce hydrogen gas. Key findings include:
- Monometallic silver (Ag) catalysts supported on activated carbon cloth showed increasing hydrogen evolution rates with increasing Ag loading up to 10 wt%, but rates decreased at 15 wt% loading likely due to poorer dispersion.
- Bimetallic catalysts with 1 wt% noble metals (platinum, palladium, rhodium) promoted on 10 wt% Ag/ACC showed enhanced hydrogen evolution rates compared to the monometallic Ag catalyst. In particular, a 10 wt% Ag-1 wt% Pt catalyst produced hydrogen at twice the rate of the 10 wt%
Similar to A [Fe(bpy)3]2+ grafted graphitic carbon nitride hybrid for visible light assisted oxidative coupling of benzylamines under mild reaction conditions (20)
Isolated Iridium Sites on Potassium-Doped Carbon-nitride wrapped Tellurium Na...Pawan Kumar
Many industrial processes such transesterification of fatty acid for biodiesel production, soap manufacturing and biosynthesis of ethanol generate glycerol as a major by-product that can be used to produce commodity chemicals. Photocatalytic transformation of glycerol is an enticing approach that can exclude the need of harsh oxidants and extraneous thermal energy. However, the product yield and selectivity remain poor due to low absorption and unsymmetrical site distribution on the catalyst surface. Herein, tellurium (Te) nanorods/nanosheets (TeNRs/NSs) wrapped potassium-doped carbon nitride (KCN) van der Waal (vdW) heterojunction (TeKCN) is designed to enhance charge separation and visible-NIR absorption. The iridium (Ir) single atom sites decoration on the TeKCN core-shell structure (TeKCNIr) promotes selective oxidation of glycerol to glyceraldehyde with a conversion of 45.6% and selectivity of 61.6% under AM1.5G irradiation. The catalytic selectivity can reach up to 88% under 450 nm monochromatic light. X-ray absorption spectroscopy (XAS) demonstrates the presence of undercoordinated IrN2O2 sites which improved catalytic selectivity for glycol oxidation. Band energies and computational calculations reveal faile charge transfer in the TeKCNIr heterostructure. EPR and scavenger tests discern that superoxide (O2•−) and hydroxyl (•OH) radicals are prime components driving glycerol oxidation.
Isolated Iridium Sites on Potassium-Doped Carbon-nitride wrapped Tellurium Na...Pawan Kumar
Many industrial processes such transesterification of fatty acid for biodiesel production, soap manufacturing and biosynthesis of ethanol generate glycerol as a major by-product that can be used to produce commodity chemicals. Photocatalytic transformation of glycerol is an enticing approach that can exclude the need of harsh oxidants and extraneous thermal energy. However, the product yield and selectivity remain poor due to low absorption and unsymmetrical site distribution on the catalyst surface. Herein, tellurium (Te) nanorods/nanosheets (TeNRs/NSs) wrapped potassium-doped carbon nitride (KCN) van der Waal (vdW) heterojunction (TeKCN) is designed to enhance charge separation and visible-NIR absorption. The iridium (Ir) single atom sites decoration on the TeKCN core-shell structure (TeKCNIr) promotes selective oxidation of glycerol to glyceraldehyde with a conversion of 45.6% and selectivity of 61.6% under AM1.5G irradiation. The catalytic selectivity can reach up to 88% under 450 nm monochromatic light. X-ray absorption spectroscopy (XAS) demonstrates the presence of undercoordinated IrN2O2 sites which improved catalytic selectivity for glycol oxidation. Band energies and computational calculations reveal faile charge transfer in the TeKCNIr heterostructure. EPR and scavenger tests discern that superoxide (O2•−) and hydroxyl (•OH) radicals are prime components driving glycerol oxidation.
Isolated Iridium Sites on Potassium-Doped Carbon-nitride wrapped Tellurium Na...Pawan Kumar
Many industrial processes such transesterification of fatty acid for biodiesel production, soap manufacturing and biosynthesis of ethanol generate glycerol as a major by-product that can be used to produce commodity chemicals. Photocatalytic transformation of glycerol is an enticing approach that can exclude the need of harsh oxidants and extraneous thermal energy. However, the product yield and selectivity remain poor due to low absorption and unsymmetrical site distribution on the catalyst surface. Herein, tellurium (Te) nanorods/nanosheets (TeNRs/NSs) wrapped potassium-doped carbon nitride (KCN) van der Waal (vdW) heterojunction (TeKCN) is designed to enhance charge separation and visible-NIR absorption. The iridium (Ir) single atom sites decoration on the TeKCN core-shell structure (TeKCNIr) promotes selective oxidation of glycerol to glyceraldehyde with a conversion of 45.6% and selectivity of 61.6% under AM1.5G irradiation. The catalytic selectivity can reach up to 88% under 450 nm monochromatic light. X-ray absorption spectroscopy (XAS) demonstrates the presence of undercoordinated IrN2O2 sites which improved catalytic selectivity for glycol oxidation. Band energies and computational calculations reveal faile charge transfer in the TeKCNIr heterostructure. EPR and scavenger tests discern that superoxide (O2•−) and hydroxyl (•OH) radicals are prime components driving glycerol oxidation.
Solar-Driven Cellulose Photorefining into Arabinose over Oxygen-Doped Carbon ...Pawan Kumar
Biomass photorefining is a promising strategy to address the energy crisis and transition toward carbon carbon-neutral society. Here, we demonstrate the feasibility of direct cellulose photorefining into arabinose by a rationally designed oxygen-doped polymeric carbon nitride, which generates favorable oxidative species (e.g., O2–, •OH) for selective oxidative reactions at neutral conditions. In addition, we also illustrate the mechanism of the photocatalytic cellulose to arabinose conversion by density functional theory calculations. The oxygen insertion derived from oxidative radicals at the C1 position of glucose within cellulose leads to oxidative cleavage of β-1,4 glycosidic linkages, resulting in the subsequent gluconic acid formation. The following decarboxylation process of gluconic acid via C1–C2 α-scissions, triggered by surface oxygen-doped active sites, generates arabinose and formic acid, respectively. This work not only offers a mechanistic understanding of cellulose photorefining to arabinose but also sets up an example for illuminating the path toward direct cellulose photorefining into value-added bioproducts under mild conditions.
Solar-Driven Cellulose Photorefining into Arabinose over Oxygen-Doped Carbon ...Pawan Kumar
Biomass photorefining is a promising strategy to address the energy crisis and transition toward carbon carbon-neutral society. Here, we demonstrate the feasibility of direct cellulose photorefining into arabinose by a rationally designed oxygen-doped polymeric carbon nitride, which generates favorable oxidative species (e.g., O2–, •OH) for selective oxidative reactions at neutral conditions. In addition, we also illustrate the mechanism of the photocatalytic cellulose to arabinose conversion by density functional theory calculations. The oxygen insertion derived from oxidative radicals at the C1 position of glucose within cellulose leads to oxidative cleavage of β-1,4 glycosidic linkages, resulting in the subsequent gluconic acid formation. The following decarboxylation process of gluconic acid via C1–C2 α-scissions, triggered by surface oxygen-doped active sites, generates arabinose and formic acid, respectively. This work not only offers a mechanistic understanding of cellulose photorefining to arabinose but also sets up an example for illuminating the path toward direct cellulose photorefining into value-added bioproducts under mild conditions.
Solar-Driven Cellulose Photorefining into Arabinose over Oxygen-Doped Carbon ...Pawan Kumar
Biomass photorefining is a promising strategy to address the energy crisis and transition toward carbon carbon-neutral society. Here, we demonstrate the feasibility of direct cellulose photorefining into arabinose by a rationally designed oxygen-doped polymeric carbon nitride, which generates favorable oxidative species (e.g., O2–, •OH) for selective oxidative reactions at neutral conditions. In addition, we also illustrate the mechanism of the photocatalytic cellulose to arabinose conversion by density functional theory calculations. The oxygen insertion derived from oxidative radicals at the C1 position of glucose within cellulose leads to oxidative cleavage of β-1,4 glycosidic linkages, resulting in the subsequent gluconic acid formation. The following decarboxylation process of gluconic acid via C1–C2 α-scissions, triggered by surface oxygen-doped active sites, generates arabinose and formic acid, respectively. This work not only offers a mechanistic understanding of cellulose photorefining to arabinose but also sets up an example for illuminating the path toward direct cellulose photorefining into value-added bioproducts under mild conditions.
Partial Thermal Condensation Mediated Synthesis of High-Density Nickel Single...Pawan Kumar
Direct selective transformation of greenhouse methane (CH4) to liquid oxygenates (methanol) can substitute energy-intensive two-step (reforming/Fischer–Tropsch) synthesis while creating environmental benefits. The development of inexpensive, selective, and robust catalysts that enable room temperature conversion will decide the future of this technology. Single-atom catalysts (SACs) with isolated active centers embedded in support have displayed significant promises in catalysis to drive challenging reactions. Herein, high-density Ni single atoms are developed and stabilized on carbon nitride (NiCN) via thermal condensation of preorganized Ni-coordinated melem units. The physicochemical characterization of NiCN with various analytical techniques including HAADF-STEM and X-ray absorption fine structure (XAFS) validate the successful formation of Ni single atoms coordinated to the heptazine-constituted CN network. The presence of uniform catalytic sites improved visible absorption and carrier separation in densely populated NiCN SAC resulting in 100% selective photoconversion of (CH4) to methanol using H2O2 as an oxidant. The superior catalytic activity can be attributed to the generation of high oxidation (NiIII═O) sites and selective C─H bond cleavage to generate •CH3 radicals on Ni centers, which can combine with •OH radicals to generate CH3OH.
Partial Thermal Condensation Mediated Synthesis of High-Density Nickel Single...Pawan Kumar
Direct selective transformation of greenhouse methane (CH4) to liquid oxygenates (methanol) can substitute energy-intensive two-step (reforming/Fischer–Tropsch) synthesis while creating environmental benefits. The development of inexpensive, selective, and robust catalysts that enable room temperature conversion will decide the future of this technology. Single-atom catalysts (SACs) with isolated active centers embedded in support have displayed significant promises in catalysis to drive challenging reactions. Herein, high-density Ni single atoms are developed and stabilized on carbon nitride (NiCN) via thermal condensation of preorganized Ni-coordinated melem units. The physicochemical characterization of NiCN with various analytical techniques including HAADF-STEM and X-ray absorption fine structure (XAFS) validate the successful formation of Ni single atoms coordinated to the heptazine-constituted CN network. The presence of uniform catalytic sites improved visible absorption and carrier separation in densely populated NiCN SAC resulting in 100% selective photoconversion of (CH4) to methanol using H2O2 as an oxidant. The superior catalytic activity can be attributed to the generation of high oxidation (NiIII═O) sites and selective C─H bond cleavage to generate •CH3 radicals on Ni centers, which can combine with •OH radicals to generate CH3OH.
Selective Cellobiose Photoreforming for Simultaneous Gluconic Acid and Syngas...Pawan Kumar
Here, we demonstrate the selective cellobiose (building block of cellulose) photoreforming for gluconic acid and syngas co-production in acidic conditions by rationally designing a bifunctional polymeric carbon nitride (CN) with potassium/sulfur co-dopant. This heteroatomic doped CN photocatalyst possesses enhanced visible light absorption, higher charge separation efficiency than pristine CN. Under acidic conditions, cellobiose is not only more efficiently hydrolyzed into glucose but also promotes the syngas and gluconic acid production. Density functional theory (DFT) calculations reveal the favorable generation of •O2− during the photocatalytic reaction, which is essential for gluconic acid production. Consequently, the fine-designed photocatalyst presents excellent cellobiose conversion (>80%) and gluconic acid selectivity (>70%) together with the co-production of syngas (~56 μmol g-1 h-1) under light illumination. The current work demonstrates the feasibility of biomass photoreforming with value-added chemicals and syngas co-production under mild condition.
Selective Cellobiose Photoreforming for Simultaneous Gluconic Acid and Syngas...Pawan Kumar
Here, we demonstrate the selective cellobiose (building block of cellulose) photoreforming for gluconic acid and syngas co-production in acidic conditions by rationally designing a bifunctional polymeric carbon nitride (CN) with potassium/sulfur co-dopant. This heteroatomic doped CN photocatalyst possesses enhanced visible light absorption, higher charge separation efficiency than pristine CN. Under acidic conditions, cellobiose is not only more efficiently hydrolyzed into glucose but also promotes the syngas and gluconic acid production. Density functional theory (DFT) calculations reveal the favorable generation of •O2− during the photocatalytic reaction, which is essential for gluconic acid production. Consequently, the fine-designed photocatalyst presents excellent cellobiose conversion (>80%) and gluconic acid selectivity (>70%) together with the co-production of syngas (~56 μmol g-1 h-1) under light illumination. The current work demonstrates the feasibility of biomass photoreforming with value-added chemicals and syngas co-production under mild condition.
Selective Cellobiose Photoreforming for Simultaneous Gluconic Acid and Syngas...Pawan Kumar
Here, we demonstrate the selective cellobiose (building block of cellulose) photoreforming for gluconic acid and syngas co-production in acidic conditions by rationally designing a bifunctional polymeric carbon nitride (CN) with potassium/sulfur co-dopant. This heteroatomic doped CN photocatalyst possesses enhanced visible light absorption, higher charge separation efficiency than pristine CN. Under acidic conditions, cellobiose is not only more efficiently hydrolyzed into glucose but also promotes the syngas and gluconic acid production. Density functional theory (DFT) calculations reveal the favorable generation of •O2− during the photocatalytic reaction, which is essential for gluconic acid production. Consequently, the fine-designed photocatalyst presents excellent cellobiose conversion (>80%) and gluconic acid selectivity (>70%) together with the co-production of syngas (~56 μmol g-1 h-1) under light illumination. The current work demonstrates the feasibility of biomass photoreforming with value-added chemicals and syngas co-production under mild condition.
Partial Thermal Condensation Mediated Synthesis of High-Density Nickel Single...Pawan Kumar
Direct selective transformation of greenhouse methane (CH4) to liquid oxygenates (methanol) can substitute energy-intensive two-step (reforming/Fischer–Tropsch) synthesis while creating environmental benefits. The development of inexpensive, selective, and robust catalysts that enable room temperature conversion will decide the future of this technology. Single-atom catalysts (SACs) with isolated active centers embedded in support have displayed significant promises in catalysis to drive challenging reactions. Herein, high-density Ni single atoms are developed and stabilized on carbon nitride (NiCN) via thermal condensation of preorganized Ni-coordinated melem units. The physicochemical characterization of NiCN with various analytical techniques including HAADF-STEM and X-ray absorption fine structure (XAFS) validate the successful formation of Ni single atoms coordinated to the heptazine-constituted CN network. The presence of uniform catalytic sites improved visible absorption and carrier separation in densely populated NiCN SAC resulting in 100% selective photoconversion of (CH4) to methanol using H2O2 as an oxidant. The superior catalytic activity can be attributed to the generation of high oxidation (NiIII═O) sites and selective C─H bond cleavage to generate •CH3 radicals on Ni centers, which can combine with •OH radicals to generate CH3OH.
Recent advancements in tuning the electronic structures of transitional metal...Pawan Kumar
The smooth transition from finite non-renewables to renewable energy conversion technologies will require efficient electrocatalysts which can harness intermittent energies to store in the form of chemical bonds. The oxygen evolution reaction (OER) impedes the widespread usage of water electrolyzers to convert H2O into H2 and persists as a bottleneck, including other energy conversion devices with sluggish four H+/e− kinetics. In this context, designing highly active and stable catalysts capable of driving a lower overpotential in the OER to produce continuous hydrogen (H2) is a primary demanded. This chapter discussed the mechanism of the OER in conventional adsorbate oxygen and lattice oxygen participation in transition metal oxides (TMOs). Further, the influences of surface engineering, doping, and defects in the TMOs and understanding the electronic structure to screen electrodes towards the structure–activity relationship are highlighted. Specifically, the adsorption strength of O 2p is understood in detail as its binding ability over the surface of TMOs can be correlated directly to the OER activity. The iterative development of TMOs in terms of understanding electronic structural attributes is essential for the commercial deployment of energy conversion technologies. The comprehensive outlook of this chapter investigates thoroughly how TMOs can be used as significant materials for the OER in the near future.
Hole transport materials (HTMs) have a significant impact on the effectiveness of organic electronic devices; therefore, we present a molecular architecture of pyrazino[2,3-g]quinoxaline (PQ10)-based room-temperature organic liquid crystalline semiconductor (OLCS) as an alternative HTM. The PQ10 compound exhibits three different rectangular columnar (Colr) phases offering an impressive hole mobility of 8.8 × 10−3 cm2V−1s−1 which is found to be dexterous than most of existing polymeric hole transport materials. The charge transport mechanism is governed by the hole polarons hopping through H-aggregates of the PQ10 molecules and the hole mobility remains nearly constant throughout the mesophase range, but it decreases with increasing applied electric field. The current-voltage characteristics of the PQ10 have also been investigated in all three Colr phases and explained via the Poole-Frenkel conduction mechanism. The dielectric spectroscopy has been eventually carried out to understand the nature of dielectric permittivity and conductivity as a function of temperature and a correlation is established between the molecular architecture of the Colr phases and aforementioned physical properties. Solar cell simulation has been additionally performed to demonstrate that the PQ10 material can be a better choice as HTM for organic electronics and photovoltaic applications.
Multifunctional carbon nitride nanoarchitectures for catalysisPawan Kumar
Catalysis is at the heart of modern-day chemical and pharmaceutical industries, and there is an urgent demand to develop metal-free, high surface area, and efficient catalysts in a scalable, reproducible and economic manner. Amongst the ever-expanding two-dimensional materials family, carbon nitride (CN) has emerged as the most researched material for catalytic applications due to its unique molecular structure with tunable visible range band gap, surface defects, basic sites, and nitrogen functionalities. These properties also endow it with anchoring capability with a large number of catalytically active sites and provide opportunities for doping, hybridization, sensitization, etc. To make considerable progress in the use of CN as a highly effective catalyst for various applications, it is critical to have an in-depth understanding of its synthesis, structure and surface sites. The present review provides an overview of the recent advances in synthetic approaches of CN, its physicochemical properties, and band gap engineering, with a focus on its exclusive usage in a variety of catalytic reactions, including hydrogen evolution reactions, overall water splitting, water oxidation, CO2 reduction, nitrogen reduction reactions, pollutant degradation, and organocatalysis. While the structural design and band gap engineering of catalysts are elaborated, the surface chemistry is dealt with in detail to demonstrate efficient catalytic performances. Burning challenges in catalytic design and future outlook are elucidated.
Production of Renewable Fuels by the Photocatalytic Reduction of CO2 using Ma...Pawan Kumar
The photo-reductive performance of natural ilmenite was boosted and the production of renewable fuels from the reduction of CO2 was enhanced by doping the natural mineral with magnesium. The doping was achieved by high energy ball milling in the presence of MgO and Mg(NO3)2. The photo-reduction of CO2 in aqueous solution led to the evolution of H2, CH4, C2H4, and C2H6, and the insertion of Mg in the structure of ilmenite enabled increases of up to 1245% in the fuel production yield, reaching total production of 210.9 µmol h-1 gcat-1. Displacements of the conduction band to more negative potentials were evidenced for the samples doped with magnesium. Indirect effects such as increases in the valence band maximum, and the introduction of intermediate energy levels were also evidenced through the measurement of the crystallite size and the determination of the band structure of the materials. Mott-Schottky analyses of the samples showed the n-type nature of the semiconductor materials and enabled the estimation of the density of charge carriers, which strongly influenced the photocatalytic performance. The strong potential of the application of natural ilmenite in gas phase artificial photosynthesis was proved by the evaluation of CO2 reduction in gas conditions, which allowed the enhancement in the selectivity and significantly increased the production of CH4 as compared to aqueous solution, reaching an important yield of CH4 of 16.1 µmol h-1 gcat-1.
Nanoengineered Au-Carbon Nitride Interfaces Enhance PhotoCatalytic Pure Water...Pawan Kumar
Photocatalytic pure water splitting using solar energy is one of the promising routes to produce sustainable green hydrogen (H2). Tuning the interfacial active site density at catalytic heterojunctions and better light management are imperative to steer the structure-activity correlations to enhance the photo-efficiency of nanocomposite photocatalysts. Herein, we report the decoration of nitrogen defects-rich carbon nitride CN(T) with metallic Au nanostructures of different morphologies and sizes to investigate their influence on the photocatalytic hydrogen evolution reactions (HER). The CN(T)-7-NP nano-heterostructure comprises Au nanoparticles (NPs) of ~7 nm and thiourea-derived defective CN exhibits an excellent H2 production rate of 76.8 µmol g–1 h–1 from pure water under simulated AM 1.5 solar irradiation. In contrast to large-size Au nanorods, the high activity of CN(T)-7-NP was attributed to their strong localized surface plasmon resonance (LSPR) mediated visible absorption and interfacial charge separation. The surface ligands used to control Au nanostructures morphology were found to play a major role in the stabilization of NPs and improve interfacial charge transport between Au NPs and CN(T). First-principles calculations revealed that defects in CN and Au-CN interfacial sites in these nanocomposites facilitate the separation of e-/h+ pairs after light excitation and provide lower energy barrier pathways for H2 production by photocatalytic water splitting.
Nanoengineered Au-Carbon Nitride Interfaces Enhance Photo-Catalytic Pure Wate...Pawan Kumar
Photocatalytic pure water splitting using solar energy is one of the promising routes to produce sustainable green hydrogen (H2). Tuning the interfacial active site density at catalytic heterojunctions and better light management are imperative to steer the structure-activity correlations to enhance the photo-efficiency of nanocomposite photocatalysts. Herein, we report the decoration of nitrogen defects-rich carbon nitride CN(T) with metallic Au nanostructures of different morphologies and sizes to investigate their influence on the photocatalytic hydrogen evolution reactions (HER). The CN(T)-7-NP nano-heterostructure comprises Au nanoparticles (NPs) of ~7 nm and thiourea-derived defective CN exhibits an excellent H2 production rate of 76.8 µmol g–1 h–1 from pure water under simulated AM 1.5 solar irradiation. In contrast to large-size Au nanorods, the high activity of CN(T)-7-NP was attributed to their strong localized surface plasmon resonance (LSPR) mediated visible absorption and interfacial charge separation. The surface ligands used to control Au nanostructures morphology were found to play a major role in the stabilization of NPs and improve interfacial charge transport between Au NPs and CN(T). First-principles calculations revealed that defects in CN and Au-CN interfacial sites in these nanocomposites facilitate the separation of e-/h+ pairs after light excitation and provide lower energy barrier pathways for H2 production by photocatalytic water splitting.
Cooperative Copper Single Atom Catalyst in Two-dimensional Carbon Nitride for...Pawan Kumar
This document summarizes a study that investigated copper single atom catalysts supported on two-dimensional carbon nitride materials for enhancing the electrochemical reduction of carbon dioxide to methane. Specifically, copper ions were incorporated into the nanoporous structures of poly(heptazine imide) and poly(triazine imide) using a room temperature ion exchange process. This allowed for high loading densities of isolated copper sites. The proximity of copper atoms within the nanopores was found to enable cooperative catalysis that boosted the selectivity and efficiency of the multi-electron conversion of CO2 to CH4. Density functional theory calculations helped explain how the copper-copper distance and coordination environment modulated the binding of reaction intermediates. Optimized copper loading in the
Bioinspired multimetal electrocatalyst for selective methane oxidationPawan Kumar
Selective partial electrooxidation of methane (CH4) to liquid oxygenates has been a long-sought goal. However, the high activation energy of C–H bonds and competing oxygen evolution reaction limit product selectivity and reaction rates. Inspired by iron (IV)-oxo containing metalloenzymes’ functionality to activate the C–H bond, here we report on the design of a copper-iron-nickel catalyst for selective oxidation of CH4 to formate via a peroxide-assisted pathway. Each catalyst serves a specific role which is confirmed via electrochemical, in situ, and theoretical studies. A combination of electrochemical and in situ spectroelectrochemical studies revealed that H2O2 oxidation on nickel led to the formation of active oxygen species which trigger the formation of iron (IV) at low voltages. Density functional theory analysis helped reveal the role of iron (IV)-oxo species in reducing the activation energy barrier for CH4 deprotonation and the critical role of copper to suppress overoxidation. Our multimetal catalyst exhibits a formate faradaic efficiency of 42% at an applied potential of 0.9 V versus a reversible hydrogen electrode.
Unlocking the mysteries of reproduction: Exploring fecundity and gonadosomati...AbdullaAlAsif1
The pygmy halfbeak Dermogenys colletei, is known for its viviparous nature, this presents an intriguing case of relatively low fecundity, raising questions about potential compensatory reproductive strategies employed by this species. Our study delves into the examination of fecundity and the Gonadosomatic Index (GSI) in the Pygmy Halfbeak, D. colletei (Meisner, 2001), an intriguing viviparous fish indigenous to Sarawak, Borneo. We hypothesize that the Pygmy halfbeak, D. colletei, may exhibit unique reproductive adaptations to offset its low fecundity, thus enhancing its survival and fitness. To address this, we conducted a comprehensive study utilizing 28 mature female specimens of D. colletei, carefully measuring fecundity and GSI to shed light on the reproductive adaptations of this species. Our findings reveal that D. colletei indeed exhibits low fecundity, with a mean of 16.76 ± 2.01, and a mean GSI of 12.83 ± 1.27, providing crucial insights into the reproductive mechanisms at play in this species. These results underscore the existence of unique reproductive strategies in D. colletei, enabling its adaptation and persistence in Borneo's diverse aquatic ecosystems, and call for further ecological research to elucidate these mechanisms. This study lends to a better understanding of viviparous fish in Borneo and contributes to the broader field of aquatic ecology, enhancing our knowledge of species adaptations to unique ecological challenges.
Immersive Learning That Works: Research Grounding and Paths ForwardLeonel Morgado
We will metaverse into the essence of immersive learning, into its three dimensions and conceptual models. This approach encompasses elements from teaching methodologies to social involvement, through organizational concerns and technologies. Challenging the perception of learning as knowledge transfer, we introduce a 'Uses, Practices & Strategies' model operationalized by the 'Immersive Learning Brain' and ‘Immersion Cube’ frameworks. This approach offers a comprehensive guide through the intricacies of immersive educational experiences and spotlighting research frontiers, along the immersion dimensions of system, narrative, and agency. Our discourse extends to stakeholders beyond the academic sphere, addressing the interests of technologists, instructional designers, and policymakers. We span various contexts, from formal education to organizational transformation to the new horizon of an AI-pervasive society. This keynote aims to unite the iLRN community in a collaborative journey towards a future where immersive learning research and practice coalesce, paving the way for innovative educational research and practice landscapes.
Phenomics assisted breeding in crop improvementIshaGoswami9
As the population is increasing and will reach about 9 billion upto 2050. Also due to climate change, it is difficult to meet the food requirement of such a large population. Facing the challenges presented by resource shortages, climate
change, and increasing global population, crop yield and quality need to be improved in a sustainable way over the coming decades. Genetic improvement by breeding is the best way to increase crop productivity. With the rapid progression of functional
genomics, an increasing number of crop genomes have been sequenced and dozens of genes influencing key agronomic traits have been identified. However, current genome sequence information has not been adequately exploited for understanding
the complex characteristics of multiple gene, owing to a lack of crop phenotypic data. Efficient, automatic, and accurate technologies and platforms that can capture phenotypic data that can
be linked to genomics information for crop improvement at all growth stages have become as important as genotyping. Thus,
high-throughput phenotyping has become the major bottleneck restricting crop breeding. Plant phenomics has been defined as the high-throughput, accurate acquisition and analysis of multi-dimensional phenotypes
during crop growing stages at the organism level, including the cell, tissue, organ, individual plant, plot, and field levels. With the rapid development of novel sensors, imaging technology,
and analysis methods, numerous infrastructure platforms have been developed for phenotyping.
EWOCS-I: The catalog of X-ray sources in Westerlund 1 from the Extended Weste...Sérgio Sacani
Context. With a mass exceeding several 104 M⊙ and a rich and dense population of massive stars, supermassive young star clusters
represent the most massive star-forming environment that is dominated by the feedback from massive stars and gravitational interactions
among stars.
Aims. In this paper we present the Extended Westerlund 1 and 2 Open Clusters Survey (EWOCS) project, which aims to investigate
the influence of the starburst environment on the formation of stars and planets, and on the evolution of both low and high mass stars.
The primary targets of this project are Westerlund 1 and 2, the closest supermassive star clusters to the Sun.
Methods. The project is based primarily on recent observations conducted with the Chandra and JWST observatories. Specifically,
the Chandra survey of Westerlund 1 consists of 36 new ACIS-I observations, nearly co-pointed, for a total exposure time of 1 Msec.
Additionally, we included 8 archival Chandra/ACIS-S observations. This paper presents the resulting catalog of X-ray sources within
and around Westerlund 1. Sources were detected by combining various existing methods, and photon extraction and source validation
were carried out using the ACIS-Extract software.
Results. The EWOCS X-ray catalog comprises 5963 validated sources out of the 9420 initially provided to ACIS-Extract, reaching a
photon flux threshold of approximately 2 × 10−8 photons cm−2
s
−1
. The X-ray sources exhibit a highly concentrated spatial distribution,
with 1075 sources located within the central 1 arcmin. We have successfully detected X-ray emissions from 126 out of the 166 known
massive stars of the cluster, and we have collected over 71 000 photons from the magnetar CXO J164710.20-455217.
The use of Nauplii and metanauplii artemia in aquaculture (brine shrimp).pptxMAGOTI ERNEST
Although Artemia has been known to man for centuries, its use as a food for the culture of larval organisms apparently began only in the 1930s, when several investigators found that it made an excellent food for newly hatched fish larvae (Litvinenko et al., 2023). As aquaculture developed in the 1960s and ‘70s, the use of Artemia also became more widespread, due both to its convenience and to its nutritional value for larval organisms (Arenas-Pardo et al., 2024). The fact that Artemia dormant cysts can be stored for long periods in cans, and then used as an off-the-shelf food requiring only 24 h of incubation makes them the most convenient, least labor-intensive, live food available for aquaculture (Sorgeloos & Roubach, 2021). The nutritional value of Artemia, especially for marine organisms, is not constant, but varies both geographically and temporally. During the last decade, however, both the causes of Artemia nutritional variability and methods to improve poorquality Artemia have been identified (Loufi et al., 2024).
Brine shrimp (Artemia spp.) are used in marine aquaculture worldwide. Annually, more than 2,000 metric tons of dry cysts are used for cultivation of fish, crustacean, and shellfish larva. Brine shrimp are important to aquaculture because newly hatched brine shrimp nauplii (larvae) provide a food source for many fish fry (Mozanzadeh et al., 2021). Culture and harvesting of brine shrimp eggs represents another aspect of the aquaculture industry. Nauplii and metanauplii of Artemia, commonly known as brine shrimp, play a crucial role in aquaculture due to their nutritional value and suitability as live feed for many aquatic species, particularly in larval stages (Sorgeloos & Roubach, 2021).
Travis Hills' Endeavors in Minnesota: Fostering Environmental and Economic Pr...Travis Hills MN
Travis Hills of Minnesota developed a method to convert waste into high-value dry fertilizer, significantly enriching soil quality. By providing farmers with a valuable resource derived from waste, Travis Hills helps enhance farm profitability while promoting environmental stewardship. Travis Hills' sustainable practices lead to cost savings and increased revenue for farmers by improving resource efficiency and reducing waste.
Or: Beyond linear.
Abstract: Equivariant neural networks are neural networks that incorporate symmetries. The nonlinear activation functions in these networks result in interesting nonlinear equivariant maps between simple representations, and motivate the key player of this talk: piecewise linear representation theory.
Disclaimer: No one is perfect, so please mind that there might be mistakes and typos.
dtubbenhauer@gmail.com
Corrected slides: dtubbenhauer.com/talks.html