Heterogeneous ‘‘Nanorust’’ containing cobalt oxide has been developed for the visible light assisted
oxidation of thiols to disulfides using molecular oxygen as an oxidant under alkaline free conditions and
therefore more environmentally friendly. Pyrolysis of heterogenized tetrasulfonated cobalt(II) phthalocyanine
(CoPcS) supported on mesoporous ceria (CeO2) transforms it into a novel heterogeneous ‘‘Nanorust’’
containing CoOx-C,N@CeO2 which exhibited higher catalytic activity than the homogeneous CoPcS as well
as the ceria immobilized CoPcS catalyst. Importantly, these catalysts could easily be recovered and recycled
for several runs, which makes the process greener and cost-effective
Photo-assisted oxidation of thiols to disulfides using cobalt ‘‘Nanorust’’ un...Pawan Kumar
Heterogeneous ‘‘Nanorust’’ containing cobalt oxide has been developed for the visible light assisted
oxidation of thiols to disulfides using molecular oxygen as an oxidant under alkaline free conditions and
therefore more environmentally friendly. Pyrolysis of heterogenized tetrasulfonated cobalt(II) phthalocyanine
(CoPcS) supported on mesoporous ceria (CeO2) transforms it into a novel heterogeneous ‘‘Nanorust’’
containing CoOx-C,N@CeO2 which exhibited higher catalytic activity than the homogeneous CoPcS as well
as the ceria immobilized CoPcS catalyst. Importantly, these catalysts could easily be recovered and recycled
for several runs, which makes the process greener and cost-effective.
This document summarizes research on using boron-doped carbon nanotubes (B-CNTs) as a catalyst for oxygen dissociation in proton exchange membrane fuel cells (PEMFCs). Density functional theory (DFT) calculations were performed to model oxygen adsorption and dissociation on a (5,5) single-walled carbon nanotube (SWCNT) with one hexagon replaced by B3C3 (B3SWCNT). The nudged elastic band (NEB) method was used to calculate minimum energy reaction paths and activation barriers. The results show an average activation barrier of 1.01 eV for oxygen dissociation on the B3SWCNT, with the most favorable path having a barrier
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
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.
Graphene oxide is synthesized by treating graphite with strong oxidizing agents like potassium chlorate, potassium permanganate, and acids. It has a layered structure with oxygen-containing functional groups such as hydroxyl and epoxy groups bonded to the basal graphene planes. These functional groups make graphene oxide hydrophilic and soluble in water. Graphene oxide can be chemically reduced by removing oxygen groups or chemically functionalized by reacting functional groups on the basal planes with other molecules through covalent bonding.
Recent progress on reduced graphene oxide....suresh kannan
The document summarizes recent progress on using reduced graphene oxide (rGO)-based materials as counter electrodes for dye-sensitized solar cells (DSSCs) as a cost-effective alternative to platinum. It discusses how rGO on its own is not effective as a counter electrode but that adding metal nanoparticles to rGO composites improves their catalytic activity and performance in DSSCs. The document reviews various rGO composites that have been studied, including those with silver, nickel, tungsten and platinum nanoparticles, as well as metal oxides and dichalcogenides. It compares the photovoltaic parameters of DSSCs using these rGO composite counter electrodes to those using conventional platinum counter electrodes
A highly stable CuS and CuS–Pt modified Cu2O/ CuO heterostructure as an effic...Taame Abraha Berhe
This document summarizes the development and characterization of a Cu2O/CuO heterostructure photocathode modified with CuS and Pt nanoparticles for efficient solar hydrogen production. The Cu2O/CuO heterostructure was synthesized via electrodeposition and annealing of copper, then modified with CuS using SILAR and Pt via sputtering. Characterization with Raman, XPS and XANES/EXAFS showed CuS interacted with Cu2O/CuO at the interface. The optimized Cu2O/CuO/CuS photocathode provided a photocurrent density of -5.4 mA cm-2, over 2.5 times higher than bare Cu2O/CuO. Adding both CuS
This document discusses the use of colloidal nanostructures for environmental contaminant capture. It provides two case studies: (1) Zr-based metal organic frameworks (MOFs) that have high surface areas and pore sizes allowing them to effectively adsorb various organic and inorganic contaminants; and (2) CuZr bimetallic nanoparticles that show favorable binding of carbon dioxide through computational modeling and experiments. The document also briefly mentions other applications of multifunctional nanoparticles for water treatment and challenges in scaling up these colloidal structures.
Photo-assisted oxidation of thiols to disulfides using cobalt ‘‘Nanorust’’ un...Pawan Kumar
Heterogeneous ‘‘Nanorust’’ containing cobalt oxide has been developed for the visible light assisted
oxidation of thiols to disulfides using molecular oxygen as an oxidant under alkaline free conditions and
therefore more environmentally friendly. Pyrolysis of heterogenized tetrasulfonated cobalt(II) phthalocyanine
(CoPcS) supported on mesoporous ceria (CeO2) transforms it into a novel heterogeneous ‘‘Nanorust’’
containing CoOx-C,N@CeO2 which exhibited higher catalytic activity than the homogeneous CoPcS as well
as the ceria immobilized CoPcS catalyst. Importantly, these catalysts could easily be recovered and recycled
for several runs, which makes the process greener and cost-effective.
This document summarizes research on using boron-doped carbon nanotubes (B-CNTs) as a catalyst for oxygen dissociation in proton exchange membrane fuel cells (PEMFCs). Density functional theory (DFT) calculations were performed to model oxygen adsorption and dissociation on a (5,5) single-walled carbon nanotube (SWCNT) with one hexagon replaced by B3C3 (B3SWCNT). The nudged elastic band (NEB) method was used to calculate minimum energy reaction paths and activation barriers. The results show an average activation barrier of 1.01 eV for oxygen dissociation on the B3SWCNT, with the most favorable path having a barrier
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
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.
Graphene oxide is synthesized by treating graphite with strong oxidizing agents like potassium chlorate, potassium permanganate, and acids. It has a layered structure with oxygen-containing functional groups such as hydroxyl and epoxy groups bonded to the basal graphene planes. These functional groups make graphene oxide hydrophilic and soluble in water. Graphene oxide can be chemically reduced by removing oxygen groups or chemically functionalized by reacting functional groups on the basal planes with other molecules through covalent bonding.
Recent progress on reduced graphene oxide....suresh kannan
The document summarizes recent progress on using reduced graphene oxide (rGO)-based materials as counter electrodes for dye-sensitized solar cells (DSSCs) as a cost-effective alternative to platinum. It discusses how rGO on its own is not effective as a counter electrode but that adding metal nanoparticles to rGO composites improves their catalytic activity and performance in DSSCs. The document reviews various rGO composites that have been studied, including those with silver, nickel, tungsten and platinum nanoparticles, as well as metal oxides and dichalcogenides. It compares the photovoltaic parameters of DSSCs using these rGO composite counter electrodes to those using conventional platinum counter electrodes
A highly stable CuS and CuS–Pt modified Cu2O/ CuO heterostructure as an effic...Taame Abraha Berhe
This document summarizes the development and characterization of a Cu2O/CuO heterostructure photocathode modified with CuS and Pt nanoparticles for efficient solar hydrogen production. The Cu2O/CuO heterostructure was synthesized via electrodeposition and annealing of copper, then modified with CuS using SILAR and Pt via sputtering. Characterization with Raman, XPS and XANES/EXAFS showed CuS interacted with Cu2O/CuO at the interface. The optimized Cu2O/CuO/CuS photocathode provided a photocurrent density of -5.4 mA cm-2, over 2.5 times higher than bare Cu2O/CuO. Adding both CuS
This document discusses the use of colloidal nanostructures for environmental contaminant capture. It provides two case studies: (1) Zr-based metal organic frameworks (MOFs) that have high surface areas and pore sizes allowing them to effectively adsorb various organic and inorganic contaminants; and (2) CuZr bimetallic nanoparticles that show favorable binding of carbon dioxide through computational modeling and experiments. The document also briefly mentions other applications of multifunctional nanoparticles for water treatment and challenges in scaling up these colloidal structures.
This document summarizes research on the effect of electrokinetics processes on minerals and molecules of expansive clay. Testing with XRD and SEM was conducted before and after electrokinetics processing using lime solution. XRD results showed that the electrokinetics process did not change the types of clay minerals present. SEM images indicated the presence of white traces on clay molecules after electrokinetics, suggesting lime was deposited on clay particles through cation exchange during the process. The research demonstrated the potential for electrokinetics to be developed as an alternative method for stabilizing expansive clays.
This document summarizes the thermal oxidation technique for synthesizing metal oxide nanowires. Thermal oxidation involves heating a metal substrate in an oxygen atmosphere to form metal oxide. Zinc oxide (ZnO) and copper oxide (CuO) nanowires have been synthesized using this method. The growth mechanism involves oxidation reactions at the metal-oxide interface, with ion diffusion through the oxide layer governed by Fick's laws. Metal ion or oxygen ion diffusion can occur via interstitial or vacancy mechanisms, determining the oxidation rate. Thermal oxidation is a simple and low-cost method to produce metal oxide nanowires.
Effect of nitrogen impurity on diamond crystal palyanov2010Layzza Tardin
This document summarizes research on the effect of nitrogen concentration on diamond crystal growth processes. The researchers varied the concentration of nitrogen in metal melts used for diamond growth, and observed four different growth outcomes: 1) single crystal diamond growth at low nitrogen concentrations, with incorporated nitrogen and defects increasing with concentration; 2) formation of aggregates of diamond crystals at intermediate concentrations; 3) crystallization of graphite instead of diamond at high concentrations; 4) increasing nitrogen concentration in the grown diamonds correlated with decreasing growth rate. The document provides details on the experimental setup and conditions used to study this effect of nitrogen concentration.
IRJET - Advances in Perovskite Solar CellsIRJET Journal
This document summarizes recent advances in perovskite solar cells. It discusses how perovskite solar cell efficiency has rapidly increased from 3.8% in 2009 to over 24.2% today, catching up to silicon solar cells. The stability of perovskite structures depends on factors like ionicity and tolerance factor. While perovskite solar cells still face stability issues with water and temperature, encapsulation and tandem cell designs with silicon are helping to address this. Research is ongoing to improve materials, device architectures and manufacturing techniques to further increase efficiency and commercial viability of these promising thin film solar cells.
International Journal of Research in Engineering and Science is an open access peer-reviewed international forum for scientists involved in research to publish quality and refereed papers. Papers reporting original research or experimentally proved review work are welcome. Papers for publication are selected through peer review to ensure originality, relevance, and readability.
The document describes the design and application of powder composite electrodes made of Cu, Co, Ni, Pt and Ir for use in electrosynthesis and electroanalysis in alkaline solutions. The electrodes were prepared by mixing 95% metal powder with 5% polyvinyl chloride binder. Characterization showed the electrodes had a rough, porous surface and good electrochemical stability, with higher current densities than metal sheet electrodes. Cyclic voltammetry testing demonstrated the composite electrodes had good stability over multiple cycles for electrooxidation reactions like ethanol oxidation in KOH solution. The composite electrodes are suitable for electrochemistry research applications requiring stable, conductive electrodes.
This document summarizes the preparation and characterization of carbon fiber-grafted poly(glycidyl methacrylate) (CF-PGMA) functionalized with the chelating ligand cyclam (CF-PGMA-Cy) for uptake of copper ions. The fibers were prepared in four steps: (1) electrografting of an aryl diazonium salt initiator onto carbon fibers, (2) surface-initiated atom transfer radical polymerization of glycidyl methacrylate, (3) functionalization of PGMA grafts with cyclam, and (4) characterization of copper ion uptake. X-ray photoelectron spectroscopy and contact angle measurements showed successful functionalization after each step. Copper uptake
The document discusses using boron-doped carbon nanotubes as a catalyst for oxygen reduction in proton exchange membrane fuel cells. Density functional theory and Nudged Elastic Band calculations were used to study oxygen dissociation across a boron-doped (5,5) single-walled carbon nanotube. The most favorable reaction path was determined to have an activation barrier of 0.5 eV, lower than previous studies using a single boron atom. This is likely due to cooperative effects of having three boron atoms and electron transfer from boron to oxygen. While the 0.5 eV barrier is still relatively high, solvent effects in real systems could further reduce it. Boron-doped carbon nanotubes
Structural aspect on carbon dioxide capture in nanotubesIJRES Journal
In this work we reported the carbon dioxide adsorption (CO2) in six different nanostructures in order
to investigate the capturing capacity of the materials at nanoscale. Here we have considered the three different
nanotubes including zinc oxide nanotube (ZnONT), silicon carbide nanotube (SiCNT) and single walled carbon
nanotube (SWCNT). Three different chiralities such as zigzag (9,0), armchair (5,5) and chiral (6,4) having
approximately same diameter are analyzed. The adsorption binding energy values under various cases are
estimated with density functional theory (DFT). We observed CO2 molecule chemisorbed on ZnONT and
SiCNT’s whereas the physisorption is predominant in CNT. To investigate the structural aspect, the tubes with
defects are studied and compared with defect free tubes. We have also analyzed the electrical properties of tubes
from HOMO, LUMO energies. Our results reveal the defected structure enhance the CO2 capture and is
predicted to be a potential candidate for environmental applications.
IOSR Journal of Applied Physics (IOSR-JAP) is an open access international journal that provides rapid publication (within a month) of articles in all areas of physics and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in applied physics. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
- The document studies using water as an alternative solvent to the commonly used acetonitrile for applying organic layers from diazonium salts.
- When using water, the diazonium salt solution had to be replaced every couple days to maintain a consistent concentration, as the salt decomposed over time, turning the solution orange.
- Preliminary results found that layers could be applied using water as a solvent, but it may lack control over completeness of the layer compared to acetonitrile.
Optical studies of nano structured la-doped zn o prepared by combustion methodsuresh800
This document summarizes research on the optical properties of lanthanum-doped zinc oxide (ZnO) nanostructures prepared using a combustion synthesis method. Coral-shaped ZnO nanostructures with an average grain size of 15 nm were successfully synthesized. Transmission electron microscopy showed the nanostructures were porous with pore sizes of 10-50 nm. X-ray diffraction analysis confirmed the wurtzite crystal structure of both pure and lanthanum-doped ZnO. Doping with lanthanum altered the structural and optical properties of ZnO. Ultraviolet-visible spectroscopy showed the band gap of ZnO increased with higher lanthanum concentration. Photoluminescence spectra exhibited lanthanum characteristic emission and a
This document discusses research on electrodepositing CdSe thin films from an acidic aqueous electrolytic bath containing organic additives, specifically monosodium L-glutamate and choline chloride. The films were characterized using XRD and SEM-EDAX. It was found that both additives led to more uniform and better crystallized deposits than without additives. Films with monosodium L-glutamate showed improved photoresponse in photoelectrochemical tests, while choline chloride led to decreased photoconductivity. The organic ions from the additives are potentially adsorbed on the CdSe, introducing defects that modify the electric properties.
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 document describes the room temperature synthesis of copper sulfide (Cu9S5), copper selenide (CuSe), lead sulfide (PbS), and lead selenide (PbSe) by reacting the elemental powders in 2-mercaptoethanol solvent for 24 hours. Characterization by powder X-ray diffraction and Raman spectroscopy showed the products were highly crystalline. Reactions in ethylene glycol also yielded copper sulfide and lead sulfide but reactions in dimercaptoethane did not yield metal chalcogenides. This solvent-mediated room temperature synthesis provides a simple method for producing these metal chalcogenide materials.
metal organic framework-carbon capture and sequestrationVasiUddin Siddiqui
MOF is a porous crystal like a spunge having an enormous surface area and provide much more rooms for storage the gases preferentially hydrogen and carbon dioxide and work as storage for next generation fuel.
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.
This document reports on the synthesis and characterization of ferrocenyltelluride derivatives. It describes the reaction of ferrocenyltelluride iodide ([FcTeI]) with iron pentacarbonyl to form either a monomeric complex bearing a diferrocenylditelluride ligand or a dimeric complex with a bridging ferrocenyltelluride ligand. It also discusses the synthesis and properties of complexes featuring terminal ferrocenyltelluride ligands, including their electrochemical behavior and ability to undergo halogenation. Additionally, it examines the use of one such complex as a metalloligand to form a three-iron containing framework.
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.
This document summarizes a study that developed a new hybrid electrocatalyst for oxygen evolution reaction (OER) by anchoring cobalt oxide (Co3O4) nanoparticles onto titanium carbide (Ti3C2) MXene nanosheets. The Co3O4/MXene hybrid (denoted CM) was synthesized using a solvothermal method. Characterization showed uniform distribution of small Co3O4 nanoparticles on MXene nanosheets. Electrochemical tests found the CM catalyst achieved overpotential of 300 mV at 10 mA/cm2 for OER, which was lower than Co3O4 or MXene alone. The enhanced performance was attributed to strong interactions and charge transfer between
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.
This document summarizes research on the effect of electrokinetics processes on minerals and molecules of expansive clay. Testing with XRD and SEM was conducted before and after electrokinetics processing using lime solution. XRD results showed that the electrokinetics process did not change the types of clay minerals present. SEM images indicated the presence of white traces on clay molecules after electrokinetics, suggesting lime was deposited on clay particles through cation exchange during the process. The research demonstrated the potential for electrokinetics to be developed as an alternative method for stabilizing expansive clays.
This document summarizes the thermal oxidation technique for synthesizing metal oxide nanowires. Thermal oxidation involves heating a metal substrate in an oxygen atmosphere to form metal oxide. Zinc oxide (ZnO) and copper oxide (CuO) nanowires have been synthesized using this method. The growth mechanism involves oxidation reactions at the metal-oxide interface, with ion diffusion through the oxide layer governed by Fick's laws. Metal ion or oxygen ion diffusion can occur via interstitial or vacancy mechanisms, determining the oxidation rate. Thermal oxidation is a simple and low-cost method to produce metal oxide nanowires.
Effect of nitrogen impurity on diamond crystal palyanov2010Layzza Tardin
This document summarizes research on the effect of nitrogen concentration on diamond crystal growth processes. The researchers varied the concentration of nitrogen in metal melts used for diamond growth, and observed four different growth outcomes: 1) single crystal diamond growth at low nitrogen concentrations, with incorporated nitrogen and defects increasing with concentration; 2) formation of aggregates of diamond crystals at intermediate concentrations; 3) crystallization of graphite instead of diamond at high concentrations; 4) increasing nitrogen concentration in the grown diamonds correlated with decreasing growth rate. The document provides details on the experimental setup and conditions used to study this effect of nitrogen concentration.
IRJET - Advances in Perovskite Solar CellsIRJET Journal
This document summarizes recent advances in perovskite solar cells. It discusses how perovskite solar cell efficiency has rapidly increased from 3.8% in 2009 to over 24.2% today, catching up to silicon solar cells. The stability of perovskite structures depends on factors like ionicity and tolerance factor. While perovskite solar cells still face stability issues with water and temperature, encapsulation and tandem cell designs with silicon are helping to address this. Research is ongoing to improve materials, device architectures and manufacturing techniques to further increase efficiency and commercial viability of these promising thin film solar cells.
International Journal of Research in Engineering and Science is an open access peer-reviewed international forum for scientists involved in research to publish quality and refereed papers. Papers reporting original research or experimentally proved review work are welcome. Papers for publication are selected through peer review to ensure originality, relevance, and readability.
The document describes the design and application of powder composite electrodes made of Cu, Co, Ni, Pt and Ir for use in electrosynthesis and electroanalysis in alkaline solutions. The electrodes were prepared by mixing 95% metal powder with 5% polyvinyl chloride binder. Characterization showed the electrodes had a rough, porous surface and good electrochemical stability, with higher current densities than metal sheet electrodes. Cyclic voltammetry testing demonstrated the composite electrodes had good stability over multiple cycles for electrooxidation reactions like ethanol oxidation in KOH solution. The composite electrodes are suitable for electrochemistry research applications requiring stable, conductive electrodes.
This document summarizes the preparation and characterization of carbon fiber-grafted poly(glycidyl methacrylate) (CF-PGMA) functionalized with the chelating ligand cyclam (CF-PGMA-Cy) for uptake of copper ions. The fibers were prepared in four steps: (1) electrografting of an aryl diazonium salt initiator onto carbon fibers, (2) surface-initiated atom transfer radical polymerization of glycidyl methacrylate, (3) functionalization of PGMA grafts with cyclam, and (4) characterization of copper ion uptake. X-ray photoelectron spectroscopy and contact angle measurements showed successful functionalization after each step. Copper uptake
The document discusses using boron-doped carbon nanotubes as a catalyst for oxygen reduction in proton exchange membrane fuel cells. Density functional theory and Nudged Elastic Band calculations were used to study oxygen dissociation across a boron-doped (5,5) single-walled carbon nanotube. The most favorable reaction path was determined to have an activation barrier of 0.5 eV, lower than previous studies using a single boron atom. This is likely due to cooperative effects of having three boron atoms and electron transfer from boron to oxygen. While the 0.5 eV barrier is still relatively high, solvent effects in real systems could further reduce it. Boron-doped carbon nanotubes
Structural aspect on carbon dioxide capture in nanotubesIJRES Journal
In this work we reported the carbon dioxide adsorption (CO2) in six different nanostructures in order
to investigate the capturing capacity of the materials at nanoscale. Here we have considered the three different
nanotubes including zinc oxide nanotube (ZnONT), silicon carbide nanotube (SiCNT) and single walled carbon
nanotube (SWCNT). Three different chiralities such as zigzag (9,0), armchair (5,5) and chiral (6,4) having
approximately same diameter are analyzed. The adsorption binding energy values under various cases are
estimated with density functional theory (DFT). We observed CO2 molecule chemisorbed on ZnONT and
SiCNT’s whereas the physisorption is predominant in CNT. To investigate the structural aspect, the tubes with
defects are studied and compared with defect free tubes. We have also analyzed the electrical properties of tubes
from HOMO, LUMO energies. Our results reveal the defected structure enhance the CO2 capture and is
predicted to be a potential candidate for environmental applications.
IOSR Journal of Applied Physics (IOSR-JAP) is an open access international journal that provides rapid publication (within a month) of articles in all areas of physics and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in applied physics. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
- The document studies using water as an alternative solvent to the commonly used acetonitrile for applying organic layers from diazonium salts.
- When using water, the diazonium salt solution had to be replaced every couple days to maintain a consistent concentration, as the salt decomposed over time, turning the solution orange.
- Preliminary results found that layers could be applied using water as a solvent, but it may lack control over completeness of the layer compared to acetonitrile.
Optical studies of nano structured la-doped zn o prepared by combustion methodsuresh800
This document summarizes research on the optical properties of lanthanum-doped zinc oxide (ZnO) nanostructures prepared using a combustion synthesis method. Coral-shaped ZnO nanostructures with an average grain size of 15 nm were successfully synthesized. Transmission electron microscopy showed the nanostructures were porous with pore sizes of 10-50 nm. X-ray diffraction analysis confirmed the wurtzite crystal structure of both pure and lanthanum-doped ZnO. Doping with lanthanum altered the structural and optical properties of ZnO. Ultraviolet-visible spectroscopy showed the band gap of ZnO increased with higher lanthanum concentration. Photoluminescence spectra exhibited lanthanum characteristic emission and a
This document discusses research on electrodepositing CdSe thin films from an acidic aqueous electrolytic bath containing organic additives, specifically monosodium L-glutamate and choline chloride. The films were characterized using XRD and SEM-EDAX. It was found that both additives led to more uniform and better crystallized deposits than without additives. Films with monosodium L-glutamate showed improved photoresponse in photoelectrochemical tests, while choline chloride led to decreased photoconductivity. The organic ions from the additives are potentially adsorbed on the CdSe, introducing defects that modify the electric properties.
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 document describes the room temperature synthesis of copper sulfide (Cu9S5), copper selenide (CuSe), lead sulfide (PbS), and lead selenide (PbSe) by reacting the elemental powders in 2-mercaptoethanol solvent for 24 hours. Characterization by powder X-ray diffraction and Raman spectroscopy showed the products were highly crystalline. Reactions in ethylene glycol also yielded copper sulfide and lead sulfide but reactions in dimercaptoethane did not yield metal chalcogenides. This solvent-mediated room temperature synthesis provides a simple method for producing these metal chalcogenide materials.
metal organic framework-carbon capture and sequestrationVasiUddin Siddiqui
MOF is a porous crystal like a spunge having an enormous surface area and provide much more rooms for storage the gases preferentially hydrogen and carbon dioxide and work as storage for next generation fuel.
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.
This document reports on the synthesis and characterization of ferrocenyltelluride derivatives. It describes the reaction of ferrocenyltelluride iodide ([FcTeI]) with iron pentacarbonyl to form either a monomeric complex bearing a diferrocenylditelluride ligand or a dimeric complex with a bridging ferrocenyltelluride ligand. It also discusses the synthesis and properties of complexes featuring terminal ferrocenyltelluride ligands, including their electrochemical behavior and ability to undergo halogenation. Additionally, it examines the use of one such complex as a metalloligand to form a three-iron containing framework.
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.
This document summarizes a study that developed a new hybrid electrocatalyst for oxygen evolution reaction (OER) by anchoring cobalt oxide (Co3O4) nanoparticles onto titanium carbide (Ti3C2) MXene nanosheets. The Co3O4/MXene hybrid (denoted CM) was synthesized using a solvothermal method. Characterization showed uniform distribution of small Co3O4 nanoparticles on MXene nanosheets. Electrochemical tests found the CM catalyst achieved overpotential of 300 mV at 10 mA/cm2 for OER, which was lower than Co3O4 or MXene alone. The enhanced performance was attributed to strong interactions and charge transfer between
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.
Cobalt Phthalocyanine Immobilized on Graphene Oxide: An Efficient Visible-Act...Pawan Kumar
New graphene oxide (GO)-tethered–CoII phthalocyanine
complex [CoPc–GO] was synthesized by a stepwise
procedure and demonstrated to be an efficient, cost-effective
and recyclable photocatalyst for the reduction of carbon
dioxide to produce methanol as the main product. The developed
GO-immobilized CoPc was characterized by X-ray
diffraction (XRD), FTIR, XPS, Raman, diffusion reflection UV/
Vis spectroscopy, inductively coupled plasma atomic emission
spectroscopy (ICP-AES), thermogravimetric analysis
(TGA), Brunauer–Emmett–Teller (BET), scanning electron microscopy
(SEM), and transmission electron microscopy (TEM).
FTIR, XPS, Raman, UV/Vis and ICP-AES along with elemental
analysis data showed that CoII–Pc complex was successfully
grafted on GO. The prepared catalyst was used for the photocatalytic
reduction of carbon dioxide by using water as
a solvent and triethylamine as the sacrificial donor. Methanol
was obtained as the major reaction product along with the
formation of minor amount of CO (0.82 %). It was found that
GO-grafted CoPc exhibited higher photocatalytic activity
than homogeneous CoPc, as well as GO, and showed good
recoverability without significant leaching during the reaction.
Quantitative determination of methanol was done by
GC flame-ionization detector (FID), and verification of product
was done by NMR spectroscopy. The yield of methanol
after 48 h of reaction by using GO–CoPc catalyst in the presence
of sacrificial donor triethylamine was found to be
3781.8881 mmolg1 cat., and the conversion rate was found
to be 78.7893 mmolg1cat.h1. After the photoreduction experiment,
the catalyst was easily recovered by filtration and
reused for the subsequent recycling experiment without significant
change in the catalytic efficiency
Cobalt Phthalocyanine Immobilized on Graphene Oxide: An Efficient Visible-Act...Pawan Kumar
Abstract: New graphene oxide (GO)-tethered–CoII phthalocyanine
complex [CoPc–GO] was synthesized by a stepwise
procedure and demonstrated to be an efficient, cost-effective
and recyclable photocatalyst for the reduction of carbon
dioxide to produce methanol as the main product. The developed
GO-immobilized CoPc was characterized by X-ray
diffraction (XRD), FTIR, XPS, Raman, diffusion reflection UV/
Vis spectroscopy, inductively coupled plasma atomic emission
spectroscopy (ICP-AES), thermogravimetric analysis
(TGA), Brunauer–Emmett–Teller (BET), scanning electron microscopy
(SEM), and transmission electron microscopy (TEM).
FTIR, XPS, Raman, UV/Vis and ICP-AES along with elemental
analysis data showed that CoII–Pc complex was successfully
grafted on GO. The prepared catalyst was used for the photocatalytic
reduction of carbon dioxide by using water as
a solvent and triethylamine as the sacrificial donor. Methanol
was obtained as the major reaction product along with the
formation of minor amount of CO (0.82 %). It was found that
GO-grafted CoPc exhibited higher photocatalytic activity
than homogeneous CoPc, as well as GO, and showed good
recoverability without significant leaching during the reaction.
Quantitative determination of methanol was done by
GC flame-ionization detector (FID), and verification of product
was done by NMR spectroscopy. The yield of methanol
after 48 h of reaction by using GO–CoPc catalyst in the presence
of sacrificial donor triethylamine was found to be
3781.8881 mmolg1 cat., and the conversion rate was found
to be 78.7893 mmolg1cat.h1. After the photoreduction experiment,
the catalyst was easily recovered by filtration and
reused for the subsequent recycling experiment without significant
change in the catalytic efficiency.
Surfactant-assisted Hydrothermal Synthesis of Ceria-Zirconia Nanostructured M...IOSR Journals
CeO2–ZrO2 oxides were prepared by the surfactant-templated method using cetyl trimethyl ammonium bromide (CTAB) as template and modified with chromium nitrate. These were characterized by XRD, FT-IR, TEM, SEM, BET and TPD-CO2. The XRD data showed that as prepared CeO2-ZrO2 powder particles have single phase cubic fluorite structure. HRTEM shows mesoscopic ordering. Average particle size is 12-13 nm as calculated from particle histogram. The nitrogen adsorption/desorption isotherm were classified to be type IV isotherm, typical of mesoporous material. The presence of uni-modal mesopores are confirmed by the pore size distribution which shows pore distribution at around 60 A°. Catalytic activity was studied towards liquid-phase oxidation of benzene.
This document summarizes research on the organocatalytic copolymerization of carbon dioxide (CO2) and oxetane. Key findings include:
1) A dual catalyst system of iodine and bicyclic guanidine enables the efficient coupling of CO2 and oxetane to produce CO2-based copolymers with high selectivity and molecular weight.
2) It is proposed that the reaction occurs via a two-step mechanism, where TMC is first formed from CO2 and oxetane and then undergoes ring-opening polymerization to incorporate oxetane units.
3) Kinetic studies support the two-step mechanism, showing selective TMC formation initially and
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
Hierarchical fe , cu- and co-beta zeolites obtained by mesotemplate free meth...seranim22
This document describes the synthesis and catalytic testing of hierarchical Fe-, Cu-, and Co-beta zeolites for N2O decomposition. Two series of beta zeolites were prepared - a conventional microporous beta zeolite (Beta) and a micro-mesoporous beta zeolite (Beta/meso) prepared using a mesotemplate-free method. Both series were ion exchanged with Fe, Cu, and Co and tested as catalysts for N2O decomposition under various conditions. The Cu-Beta catalyst showed the highest activity for N2O decomposition in inert gas, while the Cu-Beta/meso catalyst had the highest reaction rate under conditions similar to nitric acid plant waste gases.
The document discusses nanoparticles for small molecule electrocatalysis, specifically focusing on oxygen evolution reaction (OER) using Ni-Co hydroxides and oxides. It first provides background on OER and discusses how Co3O4, metal-doped Co3O4, and NiCo2O4 can be used as catalysts. It then outlines the purpose and scope of studying the composition dependence of Ni-Co hydroxides and oxides for OER using stainless steel mesh. The document reviews relevant theory around OER mechanisms and properties of different catalyst materials.
Carbon-cuprous oxide composite nanoparticles
were chemically deposited on surface of thin glass tubes of spent
energy saving lamps for solar heat collection. Carbon was
obtained from fly ash of heavy oil incomplete combustion in
electric power stations. Impurities in the carbon were removed by
leaching with mineral acids. The mineral free-carbon was then
wet ground to have a submicron size. After filtration, it was
reacted with concentrated sulfuric/fuming nitric acid mixture on
cold for 3-4 days. Potassium chlorate was then added drop wise on
hot conditions to a carbon slurry followed by filtration.
Nanocarbon sample was mixed with 5% by weight PVA to help
adhesion to the glass surface. Carbon so deposited was doped with
copper nitrate solution. After dryness, the carbon/copper nitrate
film was dipped in hydrazine hydrate to form cuprous oxide -
carbon composite, It was then roasted at 380-400 °C A heat
collector testing assembly was constructed of 5 glass coils
connected in series with a total surface area of 1250 cm2
. Heat
collection was estimated by water flowing in the glass coils that
are coated with the carbon/copper film,. Parameters affecting the
solar collection efficiency such as time of exposure and mass flow
rate of the water were studied. Results revealed that the prepared
glass coil has proven successful energy collector for solar heat.
A NOVEL PRECURSOR IN PREPARATION AND CHARACTERIZATION OF NICKEL OXIDE (NIO) A...antjjournal
Synthesis of Nickel Oxide (NiO) nanoparticles and cobalt oxide (CO3O4) materials synthesis by aqueous chemical growth (ACG) Techniques. Oxide based material having a wide band gap, and suitable for optical devices,Optoelectronic devices, UV photodetector, and Light emitting diode LEDs. The analysis
and characterizationof Nickel Oxide (NiO) and cobalt oxide (CO3O4) nanoparticles by(1) X-ray diffraction (XRD), (2) Scanning electron microscopy (SEM), and (3) Ultraviolet–visible (UV–Vis) spectroscopy.
This document summarizes research on the synthesis of amorphous silicon oxide (SiOx) nanospheres using thermal evaporation of silicon monoxide (SiO). Structural analysis using electron microscopy and spectroscopy revealed that the nanospheres were uniformly spherical and amorphous in structure, composed solely of silicon and oxygen. Photoluminescence measurements showed strong blue emission from the SiOx nanospheres. A vapor-solid growth mechanism is proposed where SiO vapors react with oxygen to form SiOx vapors which then condense and aggregate to form the amorphous nanospheres on substrate surfaces in the temperature zone of 1100-1150°C.
Asymmetric Multipole Plasmon-Mediated Catalysis Shifts the Product Selectivit...Pawan Kumar
Cu/TiO2 is a well-known photocatalyst for the photocatalytic transformation of CO2 into methane. The formation of C2+ products such as ethane and ethanol rather than methane is more interesting due to their higher energy density and economic value, but the formation of C–C bonds is currently a major challenge in CO2 photoreduction. In this context, we report the dominant formation of a C2 product, namely, ethane, from the gas-phase photoreduction of CO2 using TiO2 nanotube arrays (TNTAs) decorated with large-sized (80–200 nm) Ag and Cu nanoparticles without the use of a sacrificial agent or hole scavenger. Isotope-labeled mass spectrometry was used to verify the origin and identity of the reaction products. Under 2 h AM1.5G 1-sun illumination, the total rate of hydrocarbon production (methane + ethane) was highest for AgCu-TNTA with a total CxH2x+2 rate of 23.88 μmol g–1 h–1. Under identical conditions, the CxH2x+2 production rates for Ag-TNTA and Cu-TNTA were 6.54 and 1.39 μmol g–1 h–1, respectively. The ethane selectivity was the highest for AgCu-TNTA with 60.7%, while the ethane selectivity was found to be 15.9 and 10% for the Ag-TNTA and Cu-TNTA, respectively. Adjacent adsorption sites in our photocatalyst develop an asymmetric charge distribution due to quadrupole resonances in large metal nanoparticles and multipole resonances in Ag–Cu heterodimers. Such an asymmetric charge distribution decreases adsorbate–adsorbate repulsion and facilitates C–C coupling of reaction intermediates, which otherwise occurs poorly in TNTAs decorated with small metal nanoparticles.
Perovskite solar cells - An Introduction, By Dawn John MullasseryDawn John Mullassery
Perovskite solar cells (PSCs) are a promising photovoltaic technology that has seen rapid increases in power conversion efficiency from 9.7% to over 20% in just a few years. PSCs offer advantages over other solar cell technologies in terms of cost of raw materials, fabrication, and efficiency. However, research is still needed to address challenges such as stability in the presence of moisture and the toxicity of lead used in early PSC designs. Future work aims to remove toxicity concerns and develop thin film and flexible PSC designs to enable widespread commercialization of this emerging solar technology.
CO2 is a major greenhouse gas that contributes to global warming. Photocatalytic reduction of CO2 using solar energy provides a promising way to reduce CO2 levels while also producing useful fuels and chemicals. TiO2 is commonly used as a photocatalyst but has limitations due to its large band gap. The document discusses using hybrid photocatalysts composed of TiO2 and other semiconductors or conjugated polymers to overcome these limitations and more efficiently reduce CO2 into fuels like methane and hydrogen using visible light. Experimental results showed that these hybrid photocatalysts significantly increased the rates of CO2 reduction compared to TiO2 alone.
Density functional theory calculations were performed to investigate the structural, electronic, and CO2 adsorption properties of 55-atom bimetallic CuNi nanoparticles. The calculations revealed that decorated Cu12Ni43 and core-shell Cu42Ni13 configurations were more energetically favorable than the monometallic Cu55 and Ni55 nanoparticles. CO2 was found to chemisorb on Ni55, Cu13Ni42, Cu12Ni43, and Cu43Ni12 by undergoing a transition from linear to bent geometry and elongating the C=O bonds, while it only physisorbed on Cu55 and Cu42Ni13. The presence of surface Ni atoms played a key role in strongly adsorbing and activating CO
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.
ABSTRACT: In our previous article, the geometrical optimizations have been performed for the (CaO)n, n = 1-
4, 6, 8, 9, and 12 cluster models, [WJERT, 2019, 5 (1), 328-341]. In this study,we have investigated the
adsorption of performance NO2gas towards metal oxide clusters (CaO)n, n = 2, 3, 4, 6, 8, 9, 12) cluster models,
and focus on electron transfer between the CaO and NO2 molecule by employing density functional theory
(DFT), B3LYP method. Results show that the charge transferred goes from surface clusters to NO2 antibonding orbitals which makes more reactive, and becomes stronger. Moreover, NO2 adsorbs at the one, two
Ca2+sites forming a nitrite (NO2
−). Meanwhile, the interaction of NO2 with Lewis baseO
2−,and consequently may
form a nitrate (NO3
2−) species, which is less adsorption favorable. The total adsorption energies revealed that
NO2 gas was strongly chemisorbed on the(CaO)n, n = 2, 4, 6 and 8cluster models, whereas (CaO)n, n=3, 9 and
12 results in a weak interactions. Further, the results of optimized structure showed that the total adsorption
energies and charge transfer contributions indicated that CaO is a better acid-base than MgO, due to the
increasing basicity and bigger cationic size of the CaO. The reason for these different basicities and reactivates
can be ascribed to the different electrostatic (Madelung) potentials at the two surfaces.
Similar to Photo-assisted oxidation of thiols to disulfides using cobalt ‘‘Nanorust’’ under visible light (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.
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.
Radial Nano-Heterojunctions Consisting of CdS Nanorods Wrapped by 2D CN:PDI P...Pawan Kumar
Solar energy harvesting using semiconductor photocatalysis offers an enticing solution to two of the biggest societal challenges, energy scarcity and environmental pollution. After decades of effort, no photocatalyst exists which can simultaneously meet the demand for excellent absorption, high quantum efficiency and photochemical resilience/durability. While CdS is an excellent photocatalyst for hydrogen evolution, pollutant degradation and organic synthesis, photocorrosion of CdS leads to the deactivation of the catalyst. Surface passivation of CdS with 2D graphitic carbon nitrides (CN) such as g-C3N4 and C3N5 has been shown to mitigate the photocorrosion problem but the poor oxidizing power of photogenerated holes in CN limits the utility of this approach for photooxidation reactions. We report the synthesis of exfoliated 2D nanosheets of a modified carbon nitride constituted of tris-s-triazine (C6N7) linked pyromellitic dianhydride polydiimide (CN:PDI) with a deep oxidative highest occupied molecular orbital (HOMO) position, which ensures sufficient oxidizing power for photogenerated holes in CN. The heterojunction formed by the wrapping of mono-/few layered CN:PDI on CdS nanorods (CdS/CN:PDI) was determined to be an excellent photocatalyst for oxidation reactions including photoelectrochemical water splitting, dye decolorization and the photocatalytic conversion of benzyl alcohol to benzaldehyde. Extensive structural characterization using HR-TEM, Raman, XPS, etc., confirmed wrapping of few-layered CN:PDI on CdS nanorods. The increased photoactivity in CdS/CN:PDI catalyst was ascribed to facile electron transfer from CdS to CN:PDI in comparison to CdS/g-C3N4, leading to an increased electron density on the surface of the photocatalyst to drive chemical reactions.
Authoring a personal GPT for your research and practice: How we created the Q...Leonel Morgado
Thematic analysis in qualitative research is a time-consuming and systematic task, typically done using teams. Team members must ground their activities on common understandings of the major concepts underlying the thematic analysis, and define criteria for its development. However, conceptual misunderstandings, equivocations, and lack of adherence to criteria are challenges to the quality and speed of this process. Given the distributed and uncertain nature of this process, we wondered if the tasks in thematic analysis could be supported by readily available artificial intelligence chatbots. Our early efforts point to potential benefits: not just saving time in the coding process but better adherence to criteria and grounding, by increasing triangulation between humans and artificial intelligence. This tutorial will provide a description and demonstration of the process we followed, as two academic researchers, to develop a custom ChatGPT to assist with qualitative coding in the thematic data analysis process of immersive learning accounts in a survey of the academic literature: QUAL-E Immersive Learning Thematic Analysis Helper. In the hands-on time, participants will try out QUAL-E and develop their ideas for their own qualitative coding ChatGPT. Participants that have the paid ChatGPT Plus subscription can create a draft of their assistants. The organizers will provide course materials and slide deck that participants will be able to utilize to continue development of their custom GPT. The paid subscription to ChatGPT Plus is not required to participate in this workshop, just for trying out personal GPTs during it.
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
ESR spectroscopy in liquid food and beverages.pptxPRIYANKA PATEL
With increasing population, people need to rely on packaged food stuffs. Packaging of food materials requires the preservation of food. There are various methods for the treatment of food to preserve them and irradiation treatment of food is one of them. It is the most common and the most harmless method for the food preservation as it does not alter the necessary micronutrients of food materials. Although irradiated food doesn’t cause any harm to the human health but still the quality assessment of food is required to provide consumers with necessary information about the food. ESR spectroscopy is the most sophisticated way to investigate the quality of the food and the free radicals induced during the processing of the food. ESR spin trapping technique is useful for the detection of highly unstable radicals in the food. The antioxidant capability of liquid food and beverages in mainly performed by spin trapping technique.
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.
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.
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.
The binding of cosmological structures by massless topological defectsSérgio Sacani
Assuming spherical symmetry and weak field, it is shown that if one solves the Poisson equation or the Einstein field
equations sourced by a topological defect, i.e. a singularity of a very specific form, the result is a localized gravitational
field capable of driving flat rotation (i.e. Keplerian circular orbits at a constant speed for all radii) of test masses on a thin
spherical shell without any underlying mass. Moreover, a large-scale structure which exploits this solution by assembling
concentrically a number of such topological defects can establish a flat stellar or galactic rotation curve, and can also deflect
light in the same manner as an equipotential (isothermal) sphere. Thus, the need for dark matter or modified gravity theory is
mitigated, at least in part.