The photocatalytic properties of magnetic iron(II,III) oxide particles coated with different wt% of commer-cially available P25 TiO2(P25) using a simple wet impregnation method were measured. The producedmaterials were characterized by XRD, XPS, SEM, TEM, EDX, FTIR, ICP, Magnetic Property MeasurementSystem (MPMS) and BET (N2). After calcination at 500◦C of the magnetic particles that was loaded onlywith P25, the P25 was strongly bound through a redox reaction with the magnetic particles. It was foundthat the P25 surface coverage was almost complete (>95%) at a 1:1 mass loading ratio; at higher P25 massratios, a thicker coating was obtained. However, the photocatalytic degradation rates of terephthalic acid(TPA) and phenol for these particles at all P25 loadings was lower than those obtained for pure P25 on aper TiO2mass basis. Precoating the magnetic particles with a SiO2sol-gel layer prevented the electronhole migration and oxidation of magnetite to hematite, but also led to a weakly bound P25 layer that wasremoved by rinsing. This was overcome by adding a second TiO2sol-gel on top of the SiO2coated mag-netic particles coating for anchoring the P25 particles to the surface. While magnetic particles consistingof a silica undercoat followed by a TiO2sol-gel coating as the photocatalytic layer have been reported,our approach is to use the TiO2sol-gel coating as an adhesion layer to anchor P25 particles. The P25adhered strongly to this underlying TiO2sol-gel layer without significant loss of surface area. In both P25and our produced photocatalyst, during the photocatalytic reaction P25 is in direct contact with waterand the process occurs on the P25 and water interface. As a result, the photocatalytic degradation ratesof TPA and phenol by the P2- coated magnetic particles were found to be equivalent to those of P25.The pseudo-first order rate constants in the P25 mass basis for photocatalytic degradation of TPA were0.0152 ± 0.003 min−1and 0.0144 ± 0.007 min−1using pure P25 and SiO2sol-gel/TiO2sol-gel/P25 coatedmagnetic particles, respectively. The rate constant for phenol photocatalytic degradation was reported0.09 ± 0.02 min−1for pure P25 and 0.10 ± 0.04 min−1for SiO2sol-gel/TiO2sol-gel/P25 coated magneticparticles. The similar specific surface area of the P25 powder and the P25 anchored to the surface in SiO2sol-gel/TiO2sol-gel/P25 coated magnetic particles is the reason for these similarity for rate constants.
Effects of Precipitation pH Values on the Electrochemical Properties of β-Nic...iosrjce
IOSR Journal of Applied Chemistry (IOSR-JAC) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of applied chemistry and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in Chemical Science. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Photocatalytic Mechanism Control and Study of Carrier Dynamics in CdS@C3N5 Co...Pawan Kumar
We present a potential solution to the problem of extraction of photogenerated holes from CdS nanocrystals and nanowires. The nanosheet form of C3N5 is a low-band-gap (Eg = 2.03 eV), azo-linked graphenic carbon nitride framework formed by the polymerization of melem hydrazine (MHP). C3N5 nanosheets were either wrapped around CdS nanorods (NRs) following the synthesis of pristine chalcogenide or intercalated among them by an in situ synthesis protocol to form two kinds of heterostructures, CdS-MHP and CdS-MHPINS, respectively. CdS-MHP improved the photocatalytic degradation rate of 4-nitrophenol by nearly an order of magnitude in comparison to bare CdS NRs. CdS-MHP also enhanced the sunlight-driven photocatalytic activity of bare CdS NWs for the decolorization of rhodamine B (RhB) by a remarkable 300% through the improved extraction and utilization of photogenerated holes due to surface passivation. More interestingly, CdS-MHP provided reaction pathway control over RhB degradation. In the absence of scavengers, CdS-MHP degraded RhB through the N-deethylation pathway. When either hole scavenger or electron scavenger was added to the RhB solution, the photocatalytic activity of CdS-MHP remained mostly unchanged, while the degradation mechanism shifted to the chromophore cleavage (cycloreversion) pathway. We investigated the optoelectronic properties of CdS-C3N5 heterojunctions using density functional theory (DFT) simulations, finite difference time domain (FDTD) simulations, time-resolved terahertz spectroscopy (TRTS), and photoconductivity measurements. TRTS indicated high carrier mobilities >450 cm2 V–1 s–1 and carrier relaxation times >60 ps for CdS-MHP, while CdS-MHPINS exhibited much lower mobilities <150 cm2 V–1 s–1 and short carrier relaxation times <20 ps. Hysteresis in the photoconductive J–V characteristics of CdS NWs disappeared in CdS-MHP, confirming surface passivation. Dispersion-corrected DFT simulations indicated a delocalized HOMO and a LUMO localized on C3N5 in CdS-MHP. C3N5, with its extended π-conjugation and low band gap, can function as a shuttle to extract carriers and excitons in nanostructured heterojunctions, and enhance performance in optoelectronic devices. Our results demonstrate how carrier dynamics in core–shell heterostructures can be manipulated to achieve control over the reaction mechanism in photocatalysis.
degradation of pollution and photocatalysisPraveen Vaidya
The presentation deals with the use of conduction of photocatalytic reaction using the transition metal doped transparent semiconducting thinfilms. The precursor to film is prepared by the SILAR method, which is a chemical method.
Effects of Precipitation pH Values on the Electrochemical Properties of β-Nic...iosrjce
IOSR Journal of Applied Chemistry (IOSR-JAC) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of applied chemistry and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in Chemical Science. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Photocatalytic Mechanism Control and Study of Carrier Dynamics in CdS@C3N5 Co...Pawan Kumar
We present a potential solution to the problem of extraction of photogenerated holes from CdS nanocrystals and nanowires. The nanosheet form of C3N5 is a low-band-gap (Eg = 2.03 eV), azo-linked graphenic carbon nitride framework formed by the polymerization of melem hydrazine (MHP). C3N5 nanosheets were either wrapped around CdS nanorods (NRs) following the synthesis of pristine chalcogenide or intercalated among them by an in situ synthesis protocol to form two kinds of heterostructures, CdS-MHP and CdS-MHPINS, respectively. CdS-MHP improved the photocatalytic degradation rate of 4-nitrophenol by nearly an order of magnitude in comparison to bare CdS NRs. CdS-MHP also enhanced the sunlight-driven photocatalytic activity of bare CdS NWs for the decolorization of rhodamine B (RhB) by a remarkable 300% through the improved extraction and utilization of photogenerated holes due to surface passivation. More interestingly, CdS-MHP provided reaction pathway control over RhB degradation. In the absence of scavengers, CdS-MHP degraded RhB through the N-deethylation pathway. When either hole scavenger or electron scavenger was added to the RhB solution, the photocatalytic activity of CdS-MHP remained mostly unchanged, while the degradation mechanism shifted to the chromophore cleavage (cycloreversion) pathway. We investigated the optoelectronic properties of CdS-C3N5 heterojunctions using density functional theory (DFT) simulations, finite difference time domain (FDTD) simulations, time-resolved terahertz spectroscopy (TRTS), and photoconductivity measurements. TRTS indicated high carrier mobilities >450 cm2 V–1 s–1 and carrier relaxation times >60 ps for CdS-MHP, while CdS-MHPINS exhibited much lower mobilities <150 cm2 V–1 s–1 and short carrier relaxation times <20 ps. Hysteresis in the photoconductive J–V characteristics of CdS NWs disappeared in CdS-MHP, confirming surface passivation. Dispersion-corrected DFT simulations indicated a delocalized HOMO and a LUMO localized on C3N5 in CdS-MHP. C3N5, with its extended π-conjugation and low band gap, can function as a shuttle to extract carriers and excitons in nanostructured heterojunctions, and enhance performance in optoelectronic devices. Our results demonstrate how carrier dynamics in core–shell heterostructures can be manipulated to achieve control over the reaction mechanism in photocatalysis.
degradation of pollution and photocatalysisPraveen Vaidya
The presentation deals with the use of conduction of photocatalytic reaction using the transition metal doped transparent semiconducting thinfilms. The precursor to film is prepared by the SILAR method, which is a chemical method.
Polymeric carbon nitride-based photocatalysts for photoreforming of biomass d...Pawan Kumar
Photoreforming of biomass to value-added chemicals and fuels is a chemical approach to extract photosynthetically-trapped energy in complex biomolecules which otherwise disintegrate naturally in the environment. Designing precise photocatalytic materials that can selectively break the sturdy, nature-designed biomass with multiplex chemical composition/bonding and inaccessible sites is central to deploying this technology. Polymeric carbon nitride (CN) comprised of a 2D network of condensed heptazine/triazine (C6N7/C3N3) core has shown great promise for photoreforming of biomass derivatives due to intriguing physicochemical and optical properties. This review comprehensively summarizes the state-of-the-art applications of CN-based photocatalysts for the conversion of lignocellulosic biomass derivatives. Various chemical and structural modifications in CN structure such as doping, surface functionalization, hybridization entailing to higher selectivity and conversion have been discussed aiming at providing valuable guidance for future CN-based materials design.
Sunlight-driven water-splitting using two dimensional carbon based semiconduc...Pawan Kumar
The overwhelming challenge of depleting fossil fuels and anthropogenic carbon emissions has driven research
into alternative clean sources of energy. To achieve the goal of a carbon neutral economy, the harvesting of
sunlight by using photocatalysts to split water into hydrogen and oxygen is an expedient approach to fulfill
the energy demand in a sustainable way along with reducing the emission of greenhouse gases. Even though
the past few decades have witnessed intensive research into inorganic semiconductor photocatalysts, their
quantum efficiencies for hydrogen production from visible photons remain too low for the large scale
deployment of this technology. Visible light absorption and efficient charge separation are two key necessary
conditions for achieving the scalable production of hydrogen from water. Two-dimensional carbon based
nanoscale materials such as graphene oxide, reduced graphene oxide, carbon nitride, modified 2D carbon
frameworks and their composites have emerged as potential photocatalysts due to their astonishing
properties such as superior charge transport, tunable energy levels and bandgaps, visible light absorption,
high surface area, easy processability, quantum confinement effects, and high photocatalytic quantum yields.
The feasibility of structural and chemical modification to optimize visible light absorption and charge
separation makes carbonaceous semiconductors promising candidates to convert solar energy into chemical
energy. In the present review, we have summarized the recent advances in 2D carbonaceous photocatalysts
with respect to physicochemical and photochemical tuning for solar light mediated hydrogen evolution
Visible light assisted reduction of nitrobenzenes using Fe(bpy)3+2/rGOnanocom...Pawan Kumar
Visible-light-induced photocatalytic reduction of aromatic nitrobenzenes to the corresponding anilinesat room temperature using reduced graphene oxide (rGO) immobilized iron(II) bipyridine complex asphotocatalyst is described. The rGO-immobilized iron catalyst exhibited superior catalytic activity thanhomogeneous iron(II) bipyridine complex and much higher than metal free rGO photocatalysts. Theheterogeneous photocatalyst was found to be robust and could easily be recovered and reused for severalruns without any significant loss in photocatalytic activity.
Water-splitting photoelectrodes consisting of heterojunctions of carbon nitri...Pawan Kumar
Quinary and senary non-stoichiometric double perovskites such as Ba2Ca0.66Nb1.34-xFexO6-δ (BCNF) have been utilized for gas sensing, solid oxide fuel cells and thermochemical CO2 reduction. Herein, we examined their potential as narrow bandgap semiconductors for use in solar energy harvesting. A cobalt co-doped BCNF, Ba2Ca0.66Nb0.68Fe0.33Co0.33O6-δ (BCNFCo), exhibited an optical absorption edge at ~ 800 nm, p-type conduction and a distinct photoresponse upto 640 nm while demonstrating high thermochemical stability. A nanocomposite of BCNFCo and g-C3N4 (CN) was prepared via a facile solvent assisted exfoliation/blending approach using dichlorobenzene and glycerol at a moderate temperature. The exfoliation of g-C3N4 followed by wrapping on perovskite established an effective heterojunction between the materials for charge separation. The conjugated 2D sheets of CN enabled better charge migration resulting in increased photoelectrochemical performance. A blend composed of 40 wt% perovskite and CN performed optimally, whilst achieving a photocurrent density as high as 1.5 mA cm-2 for sunlight-driven water-splitting with a Faradaic efficiency as high as ~ 88%.
The effect of band engineering of semiconductors on photocatalyic water split...eSAT Journals
Abstract
The direct conversion of solar energy using a photocatalyst in a water splitting reaction is a source of a sustainable and clean hydrogen supply. In general, photocatalysts are semiconductors that possess valence and conduction bands. These energy bands permit the absorption of photon energy to excite electrons in the outer orbitals of the photocatalysts. Photoexcited electron and hole pairs can subsequently induce a watersplitting reaction to produce hydrogen and oxygen. Photocatalytic water splitting is affected by the band level and crystallinity of the photocatalyst. Therefore, band engineering using chemical modifications such as cationic and anionic modification could createa photocatalyst suitable for the large-scale production of hydrogen. In this paper, cationic and anionic modifications of photocatalysts and the effects of these modifications onphotocatalytic water splitting are reviewed. Keywords: Water splitting; Photocatalysis; Hydrogen
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
The threat of global warming is high due to the extensive use of fossil fuels.Using non-renewable resources is a viable solution. Sunlight can be converted in two ways - into electrical energy and into chemical energy. Water splitting and CO2 are two important methods which can be used in solar cells.
Crystal Structure, Topological and Hirshfeld Surface Analysis of a Zn(II) Zwi...Awad Albalwi
Abstract: A mononuclear Zn(II) complex of (Zn(H2L) (CH3OH) Cl2
) (1) has been synthesized by using
a nonlinear optically active Zwitterionic Schiff base which is 4-((2-hydroxy-3-methoxybenzylidene)
amino) benzoic acid (H2L). Complex 1 has been structurally analyzed by FTIR and UV spectroscopy,
TGA, Powder-XRD and single crystal X-ray diffraction. X-Ray crystallographic studies revealed Zn(II)
complex crystallizes in a P21/c space group and exists in a distorted trigonal bipyramidal geometry
(τ = 0.68).
Synthesis and characterization of mixed ligand complexes of some metals with ...Taghreed Al-Noor
This paper presents the synthesis and study of some new mixed-liagnd complexes containing nicotinamide(C6H7N2O) symbolized (NA) and phenylalanine (C9H11NO2)symbolized (pheH)] with some metal ions.
The resulting products were found to be solid crystalline complexes which have been characterized by :Melting points, Solubility, Molar conductivity.
determination the percentage of the metal in the complexes by flame(AAS), magnetic susceptipibility, Spectroscopic Method [FT-IR and UV-Vis].
The proposed structure of the complexes using program , chem office 3D(2006) .
The general formula have been given for the prepared complexes :[M(NA)2(phe)]cl
M(II): Mn(II) ,Co(II) , Ni(II) , Cu(II) , Zn(II) , Cd(II) & Hg(II) .
NA = Nicotinamide= C6H7N2O
Phe - = phenylalanine ion = C9H10NO2
MOF is a new class of material with lots of opportunity for future work. It is a coordination compound. Obviously MOF is a attractive subject for a group of researcher.
Bicrystalline Titania Photocatalyst for Reduction of CO2 to Solar FuelsA'Lester Allen
Degussa P25, a mixture of anatase and rutile crystal structures, is the most commonly used precursor to form the photoactive layer in solar cells; however, the photocatalytic activity of rutile is inferior to brookite. This presentation discusses the enhancement in photocatalytic activity of an antase brookite mixture.
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.
PHOTOCATALYTIC DEGRADATION OF RB21 DYE BY TIO2 AND ZNO UNDER NATURAL SUNLIGHT...IAEME Publication
The present work aims to degrade the RB21 dye from synthetic wastewater using
semiconductors TiO2 and ZnO. The activity of photocatalytic degradation process of dye was
carried out using different light sources of 900 W/m
2
intensity in natural sunlight from 02:00 to
04:00 pm with 48°C temperature in Ahmedabad city in the month of May, 600 Watt microwave
oven and high pressure UV-light photocatalytic reactor of wavelength 200-450 nm. All the
experiments were performed with dye concentration 50 mg/L, catalyst dosage 0.8 g, pH 7, room
temperature, irradiation time 240 min followed by 30 min in dark. All the samples were collected at
different time intervals of 30, 60, 90, 120, 150, 180, 210, 240 min for the analysis of COD
degradation and color removal. The best performances was achieved using high pressure UVphotocatalytic
reactor using TiO2. The successful result obtained using TiO2is 80% COD
degradation and 99% color removal followed by 75% COD and 99% color removal with ZnO.
Chemical kinetics was found to follow first order mechanism. The formation of intermediate
compounds and identification of the final products were carried out using LCMS/MS analysis and
FT-IR techniques.
Vapor Deposition of Semiconducting Phosphorus Allotropes into TiO2 Nanotube A...Pawan Kumar
Recent evidence of exponential environmental degradation will demand a drastic shift in research and development toward exploiting alternative energy resources such as solar energy. Here, we report the successful low-cost and easily accessible synthesis of hybrid semiconductor@TiO2 nanotube photocatalysts. In order to realize its maximum potential in harvesting photons in the visible-light range, TiO2 nanotubes have been loaded with earth-abundant, low-band-gap fibrous red and black phosphorus (P). Scanning electron microscopy– and scanning transmission electron microscopy–energy-dispersive X-ray spectroscopy, X-ray diffraction, Raman spectroscopy, X-ray photoelectron microscopy, and UV–vis measurements have been performed, substantiating the deposition of fibrous red and black P on top and inside the cavities of 100-μm-long electrochemically fabricated nanotubes. The nanotubular …
PREPARATION OF POROUS AND RECYCLABLE PVA-TIO2HYBRID HYDROGELecij
Nano TiO2, one of the most effective photocatalysts, has extensive usein fields such as air purification,
sweage treatment, water spitting, reduction of CO2, and solar cells. Nowadays, the most promising method to
recycle nano TiO2during the photocatalysis is to immobilize TiO2onto matrix, such as polyvinyl alcohol
(PVA). However, due to the slow water permeability of PVA after cross-linking, the pollutants could not
contact with nano TiO2photocatalyst in time. To overcome this problem, we dispersed calcium carbonate
particles into a PVA-TiO2 mixture and then filmed the glass. PVA-TiO2-CaCO3 films were obtained by
drying. Through thermal treatment, we obtained the cross-linked PVA-TiO2-CaCO3 films. Finally, the
calcium carbonate in the film was dissolved by hydrochloric acid, and the porous PVA-TiO2 composite
photocatalyst was obtained. The results show the addition of CaCO3 has no obvious effect on PVA
cross-linking and that a large number of cavities have been generated on the surface and inside of porous
PVA-TiO2 hybrid hydrogel film. The size of the holes is about 5-15μm, which is consistent with that of
CaCO3.The photocatalytic rate constant of porous PVA-TiO2 hybrid hydrogel film is 2.49 times higher than
that of nonporous PVA-TiO2 hybrid hydrogel film.
Polymeric carbon nitride-based photocatalysts for photoreforming of biomass d...Pawan Kumar
Photoreforming of biomass to value-added chemicals and fuels is a chemical approach to extract photosynthetically-trapped energy in complex biomolecules which otherwise disintegrate naturally in the environment. Designing precise photocatalytic materials that can selectively break the sturdy, nature-designed biomass with multiplex chemical composition/bonding and inaccessible sites is central to deploying this technology. Polymeric carbon nitride (CN) comprised of a 2D network of condensed heptazine/triazine (C6N7/C3N3) core has shown great promise for photoreforming of biomass derivatives due to intriguing physicochemical and optical properties. This review comprehensively summarizes the state-of-the-art applications of CN-based photocatalysts for the conversion of lignocellulosic biomass derivatives. Various chemical and structural modifications in CN structure such as doping, surface functionalization, hybridization entailing to higher selectivity and conversion have been discussed aiming at providing valuable guidance for future CN-based materials design.
Sunlight-driven water-splitting using two dimensional carbon based semiconduc...Pawan Kumar
The overwhelming challenge of depleting fossil fuels and anthropogenic carbon emissions has driven research
into alternative clean sources of energy. To achieve the goal of a carbon neutral economy, the harvesting of
sunlight by using photocatalysts to split water into hydrogen and oxygen is an expedient approach to fulfill
the energy demand in a sustainable way along with reducing the emission of greenhouse gases. Even though
the past few decades have witnessed intensive research into inorganic semiconductor photocatalysts, their
quantum efficiencies for hydrogen production from visible photons remain too low for the large scale
deployment of this technology. Visible light absorption and efficient charge separation are two key necessary
conditions for achieving the scalable production of hydrogen from water. Two-dimensional carbon based
nanoscale materials such as graphene oxide, reduced graphene oxide, carbon nitride, modified 2D carbon
frameworks and their composites have emerged as potential photocatalysts due to their astonishing
properties such as superior charge transport, tunable energy levels and bandgaps, visible light absorption,
high surface area, easy processability, quantum confinement effects, and high photocatalytic quantum yields.
The feasibility of structural and chemical modification to optimize visible light absorption and charge
separation makes carbonaceous semiconductors promising candidates to convert solar energy into chemical
energy. In the present review, we have summarized the recent advances in 2D carbonaceous photocatalysts
with respect to physicochemical and photochemical tuning for solar light mediated hydrogen evolution
Visible light assisted reduction of nitrobenzenes using Fe(bpy)3+2/rGOnanocom...Pawan Kumar
Visible-light-induced photocatalytic reduction of aromatic nitrobenzenes to the corresponding anilinesat room temperature using reduced graphene oxide (rGO) immobilized iron(II) bipyridine complex asphotocatalyst is described. The rGO-immobilized iron catalyst exhibited superior catalytic activity thanhomogeneous iron(II) bipyridine complex and much higher than metal free rGO photocatalysts. Theheterogeneous photocatalyst was found to be robust and could easily be recovered and reused for severalruns without any significant loss in photocatalytic activity.
Water-splitting photoelectrodes consisting of heterojunctions of carbon nitri...Pawan Kumar
Quinary and senary non-stoichiometric double perovskites such as Ba2Ca0.66Nb1.34-xFexO6-δ (BCNF) have been utilized for gas sensing, solid oxide fuel cells and thermochemical CO2 reduction. Herein, we examined their potential as narrow bandgap semiconductors for use in solar energy harvesting. A cobalt co-doped BCNF, Ba2Ca0.66Nb0.68Fe0.33Co0.33O6-δ (BCNFCo), exhibited an optical absorption edge at ~ 800 nm, p-type conduction and a distinct photoresponse upto 640 nm while demonstrating high thermochemical stability. A nanocomposite of BCNFCo and g-C3N4 (CN) was prepared via a facile solvent assisted exfoliation/blending approach using dichlorobenzene and glycerol at a moderate temperature. The exfoliation of g-C3N4 followed by wrapping on perovskite established an effective heterojunction between the materials for charge separation. The conjugated 2D sheets of CN enabled better charge migration resulting in increased photoelectrochemical performance. A blend composed of 40 wt% perovskite and CN performed optimally, whilst achieving a photocurrent density as high as 1.5 mA cm-2 for sunlight-driven water-splitting with a Faradaic efficiency as high as ~ 88%.
The effect of band engineering of semiconductors on photocatalyic water split...eSAT Journals
Abstract
The direct conversion of solar energy using a photocatalyst in a water splitting reaction is a source of a sustainable and clean hydrogen supply. In general, photocatalysts are semiconductors that possess valence and conduction bands. These energy bands permit the absorption of photon energy to excite electrons in the outer orbitals of the photocatalysts. Photoexcited electron and hole pairs can subsequently induce a watersplitting reaction to produce hydrogen and oxygen. Photocatalytic water splitting is affected by the band level and crystallinity of the photocatalyst. Therefore, band engineering using chemical modifications such as cationic and anionic modification could createa photocatalyst suitable for the large-scale production of hydrogen. In this paper, cationic and anionic modifications of photocatalysts and the effects of these modifications onphotocatalytic water splitting are reviewed. Keywords: Water splitting; Photocatalysis; Hydrogen
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
The threat of global warming is high due to the extensive use of fossil fuels.Using non-renewable resources is a viable solution. Sunlight can be converted in two ways - into electrical energy and into chemical energy. Water splitting and CO2 are two important methods which can be used in solar cells.
Crystal Structure, Topological and Hirshfeld Surface Analysis of a Zn(II) Zwi...Awad Albalwi
Abstract: A mononuclear Zn(II) complex of (Zn(H2L) (CH3OH) Cl2
) (1) has been synthesized by using
a nonlinear optically active Zwitterionic Schiff base which is 4-((2-hydroxy-3-methoxybenzylidene)
amino) benzoic acid (H2L). Complex 1 has been structurally analyzed by FTIR and UV spectroscopy,
TGA, Powder-XRD and single crystal X-ray diffraction. X-Ray crystallographic studies revealed Zn(II)
complex crystallizes in a P21/c space group and exists in a distorted trigonal bipyramidal geometry
(τ = 0.68).
Synthesis and characterization of mixed ligand complexes of some metals with ...Taghreed Al-Noor
This paper presents the synthesis and study of some new mixed-liagnd complexes containing nicotinamide(C6H7N2O) symbolized (NA) and phenylalanine (C9H11NO2)symbolized (pheH)] with some metal ions.
The resulting products were found to be solid crystalline complexes which have been characterized by :Melting points, Solubility, Molar conductivity.
determination the percentage of the metal in the complexes by flame(AAS), magnetic susceptipibility, Spectroscopic Method [FT-IR and UV-Vis].
The proposed structure of the complexes using program , chem office 3D(2006) .
The general formula have been given for the prepared complexes :[M(NA)2(phe)]cl
M(II): Mn(II) ,Co(II) , Ni(II) , Cu(II) , Zn(II) , Cd(II) & Hg(II) .
NA = Nicotinamide= C6H7N2O
Phe - = phenylalanine ion = C9H10NO2
MOF is a new class of material with lots of opportunity for future work. It is a coordination compound. Obviously MOF is a attractive subject for a group of researcher.
Bicrystalline Titania Photocatalyst for Reduction of CO2 to Solar FuelsA'Lester Allen
Degussa P25, a mixture of anatase and rutile crystal structures, is the most commonly used precursor to form the photoactive layer in solar cells; however, the photocatalytic activity of rutile is inferior to brookite. This presentation discusses the enhancement in photocatalytic activity of an antase brookite mixture.
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.
PHOTOCATALYTIC DEGRADATION OF RB21 DYE BY TIO2 AND ZNO UNDER NATURAL SUNLIGHT...IAEME Publication
The present work aims to degrade the RB21 dye from synthetic wastewater using
semiconductors TiO2 and ZnO. The activity of photocatalytic degradation process of dye was
carried out using different light sources of 900 W/m
2
intensity in natural sunlight from 02:00 to
04:00 pm with 48°C temperature in Ahmedabad city in the month of May, 600 Watt microwave
oven and high pressure UV-light photocatalytic reactor of wavelength 200-450 nm. All the
experiments were performed with dye concentration 50 mg/L, catalyst dosage 0.8 g, pH 7, room
temperature, irradiation time 240 min followed by 30 min in dark. All the samples were collected at
different time intervals of 30, 60, 90, 120, 150, 180, 210, 240 min for the analysis of COD
degradation and color removal. The best performances was achieved using high pressure UVphotocatalytic
reactor using TiO2. The successful result obtained using TiO2is 80% COD
degradation and 99% color removal followed by 75% COD and 99% color removal with ZnO.
Chemical kinetics was found to follow first order mechanism. The formation of intermediate
compounds and identification of the final products were carried out using LCMS/MS analysis and
FT-IR techniques.
Vapor Deposition of Semiconducting Phosphorus Allotropes into TiO2 Nanotube A...Pawan Kumar
Recent evidence of exponential environmental degradation will demand a drastic shift in research and development toward exploiting alternative energy resources such as solar energy. Here, we report the successful low-cost and easily accessible synthesis of hybrid semiconductor@TiO2 nanotube photocatalysts. In order to realize its maximum potential in harvesting photons in the visible-light range, TiO2 nanotubes have been loaded with earth-abundant, low-band-gap fibrous red and black phosphorus (P). Scanning electron microscopy– and scanning transmission electron microscopy–energy-dispersive X-ray spectroscopy, X-ray diffraction, Raman spectroscopy, X-ray photoelectron microscopy, and UV–vis measurements have been performed, substantiating the deposition of fibrous red and black P on top and inside the cavities of 100-μm-long electrochemically fabricated nanotubes. The nanotubular …
PREPARATION OF POROUS AND RECYCLABLE PVA-TIO2HYBRID HYDROGELecij
Nano TiO2, one of the most effective photocatalysts, has extensive usein fields such as air purification,
sweage treatment, water spitting, reduction of CO2, and solar cells. Nowadays, the most promising method to
recycle nano TiO2during the photocatalysis is to immobilize TiO2onto matrix, such as polyvinyl alcohol
(PVA). However, due to the slow water permeability of PVA after cross-linking, the pollutants could not
contact with nano TiO2photocatalyst in time. To overcome this problem, we dispersed calcium carbonate
particles into a PVA-TiO2 mixture and then filmed the glass. PVA-TiO2-CaCO3 films were obtained by
drying. Through thermal treatment, we obtained the cross-linked PVA-TiO2-CaCO3 films. Finally, the
calcium carbonate in the film was dissolved by hydrochloric acid, and the porous PVA-TiO2 composite
photocatalyst was obtained. The results show the addition of CaCO3 has no obvious effect on PVA
cross-linking and that a large number of cavities have been generated on the surface and inside of porous
PVA-TiO2 hybrid hydrogel film. The size of the holes is about 5-15μm, which is consistent with that of
CaCO3.The photocatalytic rate constant of porous PVA-TiO2 hybrid hydrogel film is 2.49 times higher than
that of nonporous PVA-TiO2 hybrid hydrogel film.
Vapor Deposition of Semiconducting Phosphorus Allotropes into TiO2 Nanotube A...Pawan Kumar
Recent evidence of exponential environmental degradation will demand a drastic shift in research and development toward
exploiting alternative energy resources such as solar energy. Here, we
report the successful low-cost and easily accessible synthesis of hybrid
semiconductor@TiO2 nanotube photocatalysts. In order to realize its
maximum potential in harvesting photons in the visible-light range, TiO2
nanotubes have been loaded with earth-abundant, low-band-gap fibrous
red and black phosphorus (P). Scanning electron microscopy− and
scanning transmission electron microscopy−energy-dispersive X-ray
spectroscopy, X-ray diffraction, Raman spectroscopy, X-ray photoelectron microscopy, and UV−vis measurements have been performed,
substantiating the deposition of fibrous red and black P on top and
inside the cavities of 100-μm-long electrochemically fabricated nanotubes. The nanotubular morphology of titania and a vapor-transport technique are utilized to form heterojunctions of P and
TiO2. Compared to pristine anatase 3.2 eV TiO2 nanotubes, the creation of heterojunctions in the hybrid material resulted in
1.5−2.1 eV photoelectrocatalysts. An enhanced photoelectrochemical water-splitting performance under visible light compared
with the individual components resulted for the P@TiO2 hybrids. This feature is due to synergistically improved charge
separation in the heterojunction and more effective visible-light absorption. The electronic band structure and charge-carrier
dynamics are investigated in detail using ultraviolet photoelectron spectroscopy and Kelvin probe force microscopy to elucidate
the charge-separation mechanism. A Fermi-level alignment in P@TiO2 heterojunctions leads to a more reductive flat-band
potential and a deeper valence band compared to pristine P and thus facilitates a better water-splitting performance. Our results
demonstrate effective conversion efficiencies for the nanostructured hybrids, which may enable future applications in
optoelectronic applications such as photodetectors, photovoltaics, photoelectrochemical catalysts, and sensors.
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.
High rate CO2 photoreduction using flame annealed TiO2 nanotubesPawan Kumar
The photocatalytic reduction of CO2 into light hydrocarbons using sunlight and water is a challenging reaction involving eight electron transfer steps; nevertheless, it has great potential to address the problem of rising anthropogenic carbon emissions and enable the use of fossil fuels in a sustainable way. Several decades after its first use, TiO2 remains one of the best performing and most durable photocatalysts for CO2 reduction albeit with a poor visible light absorption capacity. We have used flame annealing to improve the response of TiO2 to visible photons and engineered a nanotubular morphology with square-shaped cross-sections in flame-annealed nanotubes. An enhanced CH4 yield was achieved in the photoreduction of CO2 using flame annealed TiO2 nanotubes, and isotope labeled experiments confirmed the reaction products to originate from the CO2 reactant. Flame-annealed TiO2 nanotubes formed in aqueous electrolyte (FANT-aq) yielded 156.5 μmol gcatalyst–1.hr–1 of CH4, which is in the top tier of reported performance values achieved using TiO2 as a stand-alone photocatalyst. This performance resulted because appreciable amounts of CH4 were generated under visible light illumination as well. TiO2 nanotubes exhibited CO2 photoreduction activity up to a wavelength of 620 nm with visible light driven photocatalytic activity peaking at 450 nm for flame annealed TiO2 nanotubes. Isotope labelling studies, using GC–MS and gas-phase FTIR, indicated photoreduction of 13CO2 to 13CH4. The detection of 13CO in the product mixture, and the absence of HCHO and HCOOH provides strong support for the photoreduction proceeding along a carbene pathway. The enhanced CO2 photoreduction performance of FANT-aq is attributed to increased visible light absorption, square morphology, and the presence of rutile as the only crystalline phase with (110) as the dominant plane.
High rate CO2 photoreduction using flame annealed TiO2 nanotubesPawan Kumar
The photocatalytic reduction of CO2 into light hydrocarbons using sunlight and water is a challenging reaction involving eight electron transfer steps; nevertheless, it has great potential to address the problem of rising anthropogenic carbon emissions and enable the use of fossil fuels in a sustainable way. Several decades after its first use, TiO2 remains one of the best performing and most durable photocatalysts for CO2 reduction albeit with a poor visible light absorption capacity. We have used flame annealing to improve the response of TiO2 to visible photons and engineered a nanotubular morphology with square-shaped cross-sections in flame-annealed nanotubes. An enhanced CH4 yield was achieved in the photoreduction of CO2 using flame annealed TiO2 nanotubes, and isotope labeled experiments confirmed the reaction products to originate from the CO2 reactant. Flame-annealed TiO2 nanotubes
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.
PREPARATION OF POROUS AND RECYCLABLE PVA-TIO2 HYBRID HYDROGELecij
Nano TiO2, one of the most effective photocatalysts, has extensive usein fields such as air purification, sweage treatment, water spitting, reduction of CO2, and solar cells. Nowadays, the most promising method to recycle nano TiO2during the photocatalysis is to immobilize TiO2onto matrix, such as polyvinyl alcohol (PVA). However, due to the slow water permeability of PVA after cross-linking, the pollutants could not
contact with nano TiO2photocatalyst in time. To overcome this problem, we dispersed calcium carbonate particles into a PVA-TiO2 mixture and then filmed the glass. PVA-TiO2-CaCO3 films were obtained by drying. Through thermal treatment, we obtained the cross-linked PVA-TiO2-CaCO3 films. Finally, the
calcium carbonate in the film was dissolved by hydrochloric acid, and the porous PVA-TiO2 composite photocatalyst was obtained. The results show the addition of CaCO3 has no obvious effect on PVA cross-linking and that a large number of cavities have been generated on the surface and inside of porous PVA-TiO2 hybrid hydrogel film. The size of the holes is about 5-15µm, which is consistent with that of CaCO3.The photocatalytic rate constant of porous PVA-TiO2 hybrid hydrogel film is 2.49 times higher than that of nonporous PVA-TiO2
hybrid hydrogel film
tA highly efficient, recyclable and magnetically separable core-shell structured CuZnO@Fe3O4microspherewrapped with reduced graphene oxide (rGO@CuZnO@Fe3O4) photocatalyst has been developed and usedfor the photoreduction of carbon dioxide with water to produce methanol under visible light irradiation.Owing to the synergistic effect of the components and to the presence of a thin Fe2O3layer on Fe3O4,rGO@CuZnO@Fe3O44 exhibited higher catalytic activity as compared to the other possible combinationssuch as CuZnO@Fe3O42 and GO@CuZnO@Fe3O43 microspheres. The yield of methanol in case of using2 and 3 as photocatalyst was found to be 858 and 1749 mol g−1cat, respectively. However, the yieldwas increased to 2656 mol g−1cat when rGO@CuZnO@Fe3O44 was used as photocatalyst under sim-ilar experimental conditions. This superior photocatalytic activity of 4 was assumed to be due to therestoration of the sp2hybridized aromatic system in rGO, which facilitated the movement of electronsand resulted in better charge separation. The synthesized heterogeneous photocatalyst could readily berecovered by external magnet and successfully reused for six subsequent cycles without significant loss in the product yield.
Vapor growth of binary and ternary phosphorusbased semiconductors into TiO2 n...Pawan Kumar
We report successful synthesis of low band gap inorganic polyphosphide and TiO2 heterostructures with
the aid of short-way transport reactions. Binary and ternary polyphosphides (NaP7, SnIP, and (CuI)3P12)
were successfully reacted and deposited into electrochemically fabricated TiO2 nanotubes. Employing
vapor phase reaction deposition, the cavities of 100 mm long TiO2 nanotubes were infiltrated;
approximately 50% of the nanotube arrays were estimated to be infiltrated in the case of NaP7. Intensive
characterization of the hybrid materials with techniques including SEM, FIB, HR-TEM, Raman
spectroscopy, XRD, and XPS proved the successful vapor phase deposition and synthesis of the
substances on and inside the nanotubes. The polyphosphide@TiO2 hybrids exhibited superior water
splitting performance compared to pristine materials and were found to be more active at higher
wavelengths. SnIP@TiO2 emerged to be the most active among the polyphosphide@TiO2 materials. The
improved photocatalytic performance might be due to Fermi level re-alignment and a lower charge
transfer resistance which facilitated better charge separation from inorganic phosphides to TiO2.
A perovskite solar cell is a type of solar cell which includes a perovskite structured compound, most commonly a hybrid organic-inorganic lead or tin halide-based material, as the light-harvesting active layer.
Reduced graphene oxide–CuO nanocomposites for photocatalyticconversion of CO2...Pawan Kumar
Reduced graphene oxide (rGO)–copper oxide nanocomposites are prepared by covalent grafting of CuOnanorods on the rGO skeleton. Chemical and structural features of rGO–CuO nanocomposites are probedby FTIR, XPS, XRD and HRTEM analyses. Photocatalytic potential of rGO–CuO nanocomposites is exploredfor reduction of CO2into the methanol under the visible light irradiation. The breadth of CuO nanorods andthe oxidation state of Cu in the rGO–CuO/Cu2O nanocomposites are systematically varied to investigatetheir photocatalytic activities. The pristine CuO nanorods exhibited very low photocatalytic activity owingto fast recombination of charge carriers and yielded 175 mol g−1methanol, whereas rGO–Cu2O andrGO–CuO exhibited significantly improved photocatalytic activities and yielded five (862 mol g−1) andseven (1228 mol g−1) folds methanol, respectively. The superior photocatalytic activity of CuO in therGO–CuO nanocomposites was attributed to slow recombination of charge carriers and efficient transferof photo-generated electrons through the rGO skeleton. This study further excludes the use of scavengingdonor.
Reduced graphene oxide–CuO nanocomposites for photocatalyticconversion of CO2...Pawan Kumar
tReduced graphene oxide (rGO)–copper oxide nanocomposites are prepared by covalent grafting of CuOnanorods on the rGO skeleton. Chemical and structural features of rGO–CuO nanocomposites are probedby FTIR, XPS, XRD and HRTEM analyses. Photocatalytic potential of rGO–CuO nanocomposites is exploredfor reduction of CO2into the methanol under the visible light irradiation. The breadth of CuO nanorods andthe oxidation state of Cu in the rGO–CuO/Cu2O nanocomposites are systematically varied to investigatetheir photocatalytic activities. The pristine CuO nanorods exhibited very low photocatalytic activity owingto fast recombination of charge carriers and yielded 175 mol g−1methanol, whereas rGO–Cu2O andrGO–CuO exhibited significantly improved photocatalytic activities and yielded five (862 mol g−1) andseven (1228 mol g−1) folds methanol, respectively. The superior photocatalytic activity of CuO in therGO–CuO nanocomposites was attributed to slow recombination of charge carriers and efficient transferof photo-generated electrons through the rGO skeleton. This study further excludes the use of scavengingdonor.
Arrays of TiO2 nanorods embedded with fluorine doped carbon nitride quantum d...Pawan Kumar
Graphenic semiconductors such as carbon nitride are attracting increasing attention as photocatalysts due to their chemical stability, visible light absorption and excellent electronic properties. The photocatalytic activity of nanostructured TiO2 catalysts is constrained by the wide bandgap and concomitant low visible light responsivity of TiO2. In this context we present the formation of new fluorine doped carbon nitride quantum dots (CNFQDs) by solid state reaction and the subsequent examination of their heterojunctions with TiO2 for photoelectrochemical water splitting. Arrays of rutile phase TiO2 nanorods embedded with CNFQDs were synthesized by a simple in situ hydrothermal approach and the resulting nanomaterials were found to exhibit strong visible light absorption. The energetics at the heterojunction were favorable for efficient electron transfer from CNFQDs to TiO2 under visible light irradiation and …
Similar to P25 titanium dioxide coated magnetic particles: Preparation,characterization and photocatalytic activity (20)
UNDERSTANDING WHAT GREEN WASHING IS!.pdfJulietMogola
Many companies today use green washing to lure the public into thinking they are conserving the environment but in real sense they are doing more harm. There have been such several cases from very big companies here in Kenya and also globally. This ranges from various sectors from manufacturing and goes to consumer products. Educating people on greenwashing will enable people to make better choices based on their analysis and not on what they see on marketing sites.
"Understanding the Carbon Cycle: Processes, Human Impacts, and Strategies for...MMariSelvam4
The carbon cycle is a critical component of Earth's environmental system, governing the movement and transformation of carbon through various reservoirs, including the atmosphere, oceans, soil, and living organisms. This complex cycle involves several key processes such as photosynthesis, respiration, decomposition, and carbon sequestration, each contributing to the regulation of carbon levels on the planet.
Human activities, particularly fossil fuel combustion and deforestation, have significantly altered the natural carbon cycle, leading to increased atmospheric carbon dioxide concentrations and driving climate change. Understanding the intricacies of the carbon cycle is essential for assessing the impacts of these changes and developing effective mitigation strategies.
By studying the carbon cycle, scientists can identify carbon sources and sinks, measure carbon fluxes, and predict future trends. This knowledge is crucial for crafting policies aimed at reducing carbon emissions, enhancing carbon storage, and promoting sustainable practices. The carbon cycle's interplay with climate systems, ecosystems, and human activities underscores its importance in maintaining a stable and healthy planet.
In-depth exploration of the carbon cycle reveals the delicate balance required to sustain life and the urgent need to address anthropogenic influences. Through research, education, and policy, we can work towards restoring equilibrium in the carbon cycle and ensuring a sustainable future for generations to come.
Diabetes is a rapidly and serious health problem in Pakistan. This chronic condition is associated with serious long-term complications, including higher risk of heart disease and stroke. Aggressive treatment of hypertension and hyperlipideamia can result in a substantial reduction in cardiovascular events in patients with diabetes 1. Consequently pharmacist-led diabetes cardiovascular risk (DCVR) clinics have been established in both primary and secondary care sites in NHS Lothian during the past five years. An audit of the pharmaceutical care delivery at the clinics was conducted in order to evaluate practice and to standardize the pharmacists’ documentation of outcomes. Pharmaceutical care issues (PCI) and patient details were collected both prospectively and retrospectively from three DCVR clinics. The PCI`s were categorized according to a triangularised system consisting of multiple categories. These were ‘checks’, ‘changes’ (‘change in drug therapy process’ and ‘change in drug therapy’), ‘drug therapy problems’ and ‘quality assurance descriptors’ (‘timer perspective’ and ‘degree of change’). A verified medication assessment tool (MAT) for patients with chronic cardiovascular disease was applied to the patients from one of the clinics. The tool was used to quantify PCI`s and pharmacist actions that were centered on implementing or enforcing clinical guideline standards. A database was developed to be used as an assessment tool and to standardize the documentation of achievement of outcomes. Feedback on the audit of the pharmaceutical care delivery and the database was received from the DCVR clinic pharmacist at a focus group meeting.
Willie Nelson Net Worth: A Journey Through Music, Movies, and Business Venturesgreendigital
Willie Nelson is a name that resonates within the world of music and entertainment. Known for his unique voice, and masterful guitar skills. and an extraordinary career spanning several decades. Nelson has become a legend in the country music scene. But, his influence extends far beyond the realm of music. with ventures in acting, writing, activism, and business. This comprehensive article delves into Willie Nelson net worth. exploring the various facets of his career that have contributed to his large fortune.
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Introduction
Willie Nelson net worth is a testament to his enduring influence and success in many fields. Born on April 29, 1933, in Abbott, Texas. Nelson's journey from a humble beginning to becoming one of the most iconic figures in American music is nothing short of inspirational. His net worth, which estimated to be around $25 million as of 2024. reflects a career that is as diverse as it is prolific.
Early Life and Musical Beginnings
Humble Origins
Willie Hugh Nelson was born during the Great Depression. a time of significant economic hardship in the United States. Raised by his grandparents. Nelson found solace and inspiration in music from an early age. His grandmother taught him to play the guitar. setting the stage for what would become an illustrious career.
First Steps in Music
Nelson's initial foray into the music industry was fraught with challenges. He moved to Nashville, Tennessee, to pursue his dreams, but success did not come . Working as a songwriter, Nelson penned hits for other artists. which helped him gain a foothold in the competitive music scene. His songwriting skills contributed to his early earnings. laying the foundation for his net worth.
Rise to Stardom
Breakthrough Albums
The 1970s marked a turning point in Willie Nelson's career. His albums "Shotgun Willie" (1973), "Red Headed Stranger" (1975). and "Stardust" (1978) received critical acclaim and commercial success. These albums not only solidified his position in the country music genre. but also introduced his music to a broader audience. The success of these albums played a crucial role in boosting Willie Nelson net worth.
Iconic Songs
Willie Nelson net worth is also attributed to his extensive catalog of hit songs. Tracks like "Blue Eyes Crying in the Rain," "On the Road Again," and "Always on My Mind" have become timeless classics. These songs have not only earned Nelson large royalties but have also ensured his continued relevance in the music industry.
Acting and Film Career
Hollywood Ventures
In addition to his music career, Willie Nelson has also made a mark in Hollywood. His distinctive personality and on-screen presence have landed him roles in several films and television shows. Notable appearances include roles in "The Electric Horseman" (1979), "Honeysuckle Rose" (1980), and "Barbarosa" (1982). These acting gigs have added a significant amount to Willie Nelson net worth.
Television Appearances
Nelson's char
Natural farming @ Dr. Siddhartha S. Jena.pptxsidjena70
A brief about organic farming/ Natural farming/ Zero budget natural farming/ Subash Palekar Natural farming which keeps us and environment safe and healthy. Next gen Agricultural practices of chemical free farming.
Micro RNA genes and their likely influence in rice (Oryza sativa L.) dynamic ...Open Access Research Paper
Micro RNAs (miRNAs) are small non-coding RNAs molecules having approximately 18-25 nucleotides, they are present in both plants and animals genomes. MiRNAs have diverse spatial expression patterns and regulate various developmental metabolisms, stress responses and other physiological processes. The dynamic gene expression playing major roles in phenotypic differences in organisms are believed to be controlled by miRNAs. Mutations in regions of regulatory factors, such as miRNA genes or transcription factors (TF) necessitated by dynamic environmental factors or pathogen infections, have tremendous effects on structure and expression of genes. The resultant novel gene products presents potential explanations for constant evolving desirable traits that have long been bred using conventional means, biotechnology or genetic engineering. Rice grain quality, yield, disease tolerance, climate-resilience and palatability properties are not exceptional to miRN Asmutations effects. There are new insights courtesy of high-throughput sequencing and improved proteomic techniques that organisms’ complexity and adaptations are highly contributed by miRNAs containing regulatory networks. This article aims to expound on how rice miRNAs could be driving evolution of traits and highlight the latest miRNA research progress. Moreover, the review accentuates miRNAs grey areas to be addressed and gives recommendations for further studies.
WRI’s brand new “Food Service Playbook for Promoting Sustainable Food Choices” gives food service operators the very latest strategies for creating dining environments that empower consumers to choose sustainable, plant-rich dishes. This research builds off our first guide for food service, now with industry experience and insights from nearly 350 academic trials.
Characterization and the Kinetics of drying at the drying oven and with micro...Open Access Research Paper
The objective of this work is to contribute to valorization de Nephelium lappaceum by the characterization of kinetics of drying of seeds of Nephelium lappaceum. The seeds were dehydrated until a constant mass respectively in a drying oven and a microwawe oven. The temperatures and the powers of drying are respectively: 50, 60 and 70°C and 140, 280 and 420 W. The results show that the curves of drying of seeds of Nephelium lappaceum do not present a phase of constant kinetics. The coefficients of diffusion vary between 2.09.10-8 to 2.98. 10-8m-2/s in the interval of 50°C at 70°C and between 4.83×10-07 at 9.04×10-07 m-8/s for the powers going of 140 W with 420 W the relation between Arrhenius and a value of energy of activation of 16.49 kJ. mol-1 expressed the effect of the temperature on effective diffusivity.
Artificial Reefs by Kuddle Life Foundation - May 2024punit537210
Situated in Pondicherry, India, Kuddle Life Foundation is a charitable, non-profit and non-governmental organization (NGO) dedicated to improving the living standards of coastal communities and simultaneously placing a strong emphasis on the protection of marine ecosystems.
One of the key areas we work in is Artificial Reefs. This presentation captures our journey so far and our learnings. We hope you get as excited about marine conservation and artificial reefs as we are.
Please visit our website: https://kuddlelife.org
Our Instagram channel:
@kuddlelifefoundation
Our Linkedin Page:
https://www.linkedin.com/company/kuddlelifefoundation/
and write to us if you have any questions:
info@kuddlelife.org
2. 250 R.E. Kalan et al. / Applied Catalysis B: Environmental 187 (2016) 249–258
Magnetic Particles
Mixed with P25 pasteCoated with SiO2
Calcined at 500 °C
Grounded and Washed
FPx
Mixed with P25 paste
Calcined at 500 ° C
Grounded and Washed
FSPx
Mixed with P25 paste
Calcined at 500 ° C
Grounded and Washed
FSTPx
Coated with TiO2
Fig. 1. Flow chart for preparation of the coated magnetic particles.
with band gap energies of 3.2 eV and 3.0 eV, respectively [7–11].
A critical issue in using P25 suspensions arises from the difficulty
in removing the P25 from a suspension; separation and recovery
of the P25 with a conventional filtration method is time consum-
ing and economically not practical. One approach to overcome this
hurdle is to immobilize a TiO2 sol-gel layer on different substrates
such as glass, stainless steel, silica, clay [12–14], and magnetic parti-
cles [8,15–18]. For the latter, a particular attraction of using coated
magnetic particles is that they could be introduced to the water
supply upstream from the UV treatment subsystem and captured
downstream with a magnet. The TiO2-coated magnetic particles
would then be recycled back upstream of the UV system [19].
When using magnetic particles such as magnetite (Fe3O4), the
common approach is to apply a SiO2 undercoat before applying a
TiO2 layer [20,21]. This is because the direct contact of TiO2 with the
iron oxide core leads to lower photocatalytic activity. The conduc-
tion band in the iron oxide is lower in energy than TiO2 and thus,
the photo-generated holes in the TiO2 layer readily migrate into the
iron oxide lattice resulting in lower radical production levels at the
TiO2/water interface. Furthermore, iron oxide has a narrow band
gap and electron-hole recombination occurs readily in this material
[7,22,23]. Electron transfer from the TiO2 conduction band into the
iron oxide core results in the reductive dissolution of Fe(III) [21,22].
The SiO2 undercoat overcomes this problem by providing an insu-
lative layer between the iron oxide from the TiO2. The SiO2 layer has
the added advantage of acting as a hole trapping layer preventing
electron-hole recombination in the TiO2 structure [8,15,18,24,25].
While there is an improvement in photocatalytic degradation using
a SiO2 barrier, these materials still exhibit lower catalytic activity
than P25. These lower activities are reported to be because of a
lower surface area or hole migration to the core due to partial SiO2
coverage [26–28].
The formation and use of a TiO2-coating on top of the silica bar-
rier layer to degrade organic compounds in water has been the
subject of several studies [7,16,21,27,29–32]. In all cases, both the
SiO2 and TiO2 layers are deposited using sol-gel methods that pro-
duce an amorphous TiO2 coating which when upon calcination at
an elevated temperature is converted to anatase or rutile. Gener-
ally, the thickness of the TiO2 layer synthesized on the magnetic
particles surface is in the range of 5–10 nm [16,17,22,33,34]. How-
ever, in most cases, the photocatalytic degradation rates of organic
compounds by these photocatalysts are lower compared to that
of P25 [26–28]. An alternative approach to synthesis using a sol-
gel TiO2 layer is to directly coat the magnetic core with a layer
of P25 particles. Typically the P25 is added to sol-gel formulation
containing a TiO2 precursor or is blended with iron oxide parti-
cles or SiO2 coated iron oxides [19,26,27]. The material is then
calcined at an elevated temperature to sinter the P25 to the mag-
netic particles. This approach is attractive due to its simplicity.
This study focuses on the photocatalytic performance and material
optimization of P25-coated magnetic particles. More important,
there have been no examples reported where P25-coated magnetic
particles have shown to have equal or better photocatalytic degra-
dation rates compared to pure P25. However, direct comparison of
photocatalytic activities is difficult, since factors such as the pho-
tocatalyst concentration and the adsorption of the compound onto
the catalyst could be different [7,35,36]. For example, increasing
photocatalyst concentration increase the photocatalytic degrada-
tion rate, but it can also increase the opacity of the suspension
and cause scattering of the UV light [35]. As a result, the basis for
reported comparisons are often empirical in nature or not stated.
When coating magnetic particles with a P25/TiO2 sol-gel matrix
[19], the coatings most likely have a portion of the P25 encased in
the TiO2 sol-gel matrix and not directly in contact with water. In
our work, a thin TiO2 sol-gel film was first deposited on top of the
silica-coated magnetic particles followed by deposition of P25 in a
separate step. Upon heating at 500 ◦C, the P25 is anchored to the
underlying TiO2 sol-gel film via formation of Ti-O-Ti bonds. This
led to a P25 layer that effectively had no reduction in effective
surface area in contact with the water and resulted in photocat-
alytic degradation levels for terephthalic acid (TPA) and phenol
which were equivalent to the P25 on a P25 mass basis. While both
a silica and TiO2 sol-gel coating were required, the TiO2 sol-gel
coating in our approach was not used as the photocatalytic layer
but rather as an adhesion layer [12,37–40] for anchoring the P25
particulates. We used TPA and phenol in this study because they
are common standard probes for measuring photocatalytic activ-
ities [41,42]. Further, TPA is commonly used to characterize HO•
production [43].
3. R.E. Kalan et al. / Applied Catalysis B: Environmental 187 (2016) 249–258 251
2. Experimental
2.1. Chemicals
The magnetite particles (Fe3O4, iron(III, II) oxide, 50–100 nm,
97% trace metals basis) were obtained from Aldrich, and the P25
TiO2 powder was obtained from Evonik (formerly Degussa). Anhy-
drous ethanol (200 proof), 2-propanol (99.99%), aqueous ammonia
(wt% 28.0–30.0 NH3 basis), tetraorthosilicate (TEOS, 99.99%), tita-
nium(IV) isopropoxide (99.99%), terephthalic acid (TPA, 98%),
phenol (99%), and 2-hydroxyterephthalic acid (hTPA, 97%) were
purchased from Sigma Aldrich. Deionized water (DI, 18 M cm)
was obtained from a Millipore gradient A10 water purification sys-
tem. Nitrocellulose membranes of 0.45 and 0.22 ᮀm pore size were
obtained from Millipore.
2.2. Synthesis of photocatalysts
P25-coated magnetic particles were prepared using three dif-
ferent pathways as described in Fig. 1. Photos of samples produced
at various steps along the preparative pathway are provided in the
SI section (Fig. S1).
2.2.1. SiO2-coated magnetic particles (FS)
Magnetic particles were coated with a SiO2 layer using a sol-gel
method described elsewhere [8]. In brief, a 1.00 g sample of mag-
netic particles was dispersed into a solution containing 400 ml of
ethanol, 100 ml of DI water and 12 ml of ammonia. The suspen-
sion was ultrasonicated for 30 min and then transferred to a 1 l
beaker. TEOS (3.5 ml) was then added drop-wise over a period of
a minimum of 15 min, while vigorously stirring at 500 rpm, and
the suspension was stirred for an additional 5 h. The particles were
removed from the suspension by placing a magnet on the side of
the beaker and decanting the solution phase. The particles were
then rinsed with DI water several times and dried in the vacuum
oven at 50 ◦C for 2 h.
2.2.2. Sol-gel TiO2- and SiO2-coated magnetic particles (FST)
SiO2-coated magnetic particles were coated with TiO2 using
a sol-gel method reported elsewhere [8,30]. A 0.50 g sample of
the FS particles was dispersed in 80 ml of ethanol and stirred at
500 rpm for 10 min. Then, a freshly prepared solution of 2.4 ml of
titanium(IV) isopropoxide in 16 ml ethanol was added drop-wise
(minimum of 15 min) to the particulate suspension at 70 ◦C while
vigorously stirring at 500 rpm. The suspension was then stirred for
an additional 12 h. The particles were removed from the suspen-
sion by placing a magnet on the side of the beaker and decanting
the solution phase. These particles were then rinsed with DI water
several times and dried in the vacuum oven at 60 ◦C for 2 h. The
dried particles were heated in air to 500 ◦C at a rate of 5 ◦C min−1,
held at this temperature for 5 h, and then cooled down to room
temperature at a rate of 5 ◦C min−1.
2.2.3. P25-coated magnetic particles (FPx, FSP and FSTPx)
A thick paste was prepared by adding 0.4 ml DI water to 0.50 g of
P25. The paste was mixed thoroughly using a spatula to produce a
uniform mixture (Fig. S1a). Three types of particles were prepared
by adding bare magnetic particles (FPx), FS particles (FSP), or FST
particles (FSTPx) to the P25 paste (Fig. S1b). The pastes were then
mixed thoroughly using a spatula to produce a homogeneous mix-
ture. The amounts of magnetic particle added to the paste are given
in Table 1. Table 1 also provides the sample labeling system used in
this manuscript. The paste was then heated in air to 500 ◦C at a rate
of 5 ◦C min−1, held at 500 ◦C for 5 h, followed by cooling to room
temperature at a rate of 5 ◦C min−1 (Fig. S1c). Samples were then
ground (Fig. S1d) in a mortar and pestle and size selected (<150 m)
Table 1
Amounts used in preparation of each material. F, S, T and P, refer to iron oxide, sol-
gel grown SiO2 layer, sol-gel grown TiO2 layer, and P25, respectively. The numbers
refer to the mass ratio of the iron oxide and P25 in each sample.
Samples P25 (g) Magnetic
particles (g)
TEOS (ml) Titanium(IV)
Isopropoxide (ml)
FP1 0.500 0.500 0 0
FP2 0.500 0.250 0 0
FP3 0.500 0.167 0 0
FP4 0.500 0.125 0 0
FP5 0.500 0.100 0 0
FSP2 0.500 0.250 2.6 0
FSTP1 0.250 0.250 2.6 2.4
FSTP2 0.500 0.250 2.6 2.4
by passing the particles through a Cole-Palmer sieve shaker. The
powders were rinsed with DI water and removed from the suspen-
sion by placing a magnet on the side of the beaker and decanting
the solution phase. The particles were then dried at 80 ◦C for 1 h.
2.3. Particle characterization
Powder X-ray diffraction (XRD) patterns of particles were
obtained on a PANanalytical X’pert MRD X-ray diffraction system
using Cu-K␣ radiation at a scan rate of 0.3◦ s−1. X-ray photoelectron
spectroscopy (XPS) was obtained on a dual anode VG Microtech
X-ray source and a SPECS HSA2000 analyzer. Scanning electron
microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX)
were measured on a Zeiss N vision 40 system. The particles mor-
phology and size distribution were examined by transmission
electron microscopy (TEM) on a Philips CM10, 100kv, camera
controller Orius, CCD. The BET surface area was determined by
a multipoint method on a Micromeritics ASAP 2020 using the
adsorption data in the relative pressure range (P/P0) of 0.02–0.45.
The elemental composition was obtained by digesting the sam-
ples in a solution containing equal volumes of HF(5%), HCl(6 M),
and HNO3(7.5 M). The digested samples were analyzed using a
Thermo Element2 sector field Inductively Coupled Plasma Mass
Spectrometer (ICPMS). FTIR spectra were recorded on ABB FTLA
2000 spectrometers. Magnetic properties were measured using
a Magnetic Property Measurement System (MPMS XL; Quantum
Design, Inc.) at 300 K and magnetic fields of 0 to ±70 kOe, and the
data was analyzed using Igor Pro. The fluorescence spectra were
recorded on a Jobin Yvon Fluorolog-3 spectrofluorometer equipped
with emission and excitation monochromators, a 400 W Xenon
lamp source, and a photomultiplier tube. High Performance Liquid
Chromatography (HPLC) analysis of phenol and TPA concentrations
were performed on an Agilent 1100 with a C8 column (100A).
2.4. Photocatalytic degradation experiments
Photocatalytic activities of the coated magnetic particles were
measured using TPA as a probe molecule for HO• production. The
reaction product of TPA with HO• is hTPA whose fluorescence inten-
sity is proportional to the HO• concentration [43]. A 0.075 g sample
of the magnetic particles was dispersed in 50 ml DI water in a 250 ml
quartz beaker and sonicated for 1 min. The particles in the suspen-
sion were then collected by placing a magnet at the bottom side
of the beaker and decanting the solution phase. Next, 150 ml of a
83 mg/L TPA solution was added to the beaker containing the mag-
netic particles. The pH was in the 6.0-6.4 range after the addition
of the catalysts and remained in this range over the entire experi-
ment. The beaker was then placed in the photochemical chamber of
a Rayonet Model RPR-100 reactor that was equipped with four RPR-
2537 Å lamps, each emitting radiation in the UV-C range (∼254 nm)
of 1.26 × 10−5 einstein min−1 (15.6 W m−2), measured by the fer-
rioxalate actinometry method [44,45]. A 254 nm lamp was selected
4. 252 R.E. Kalan et al. / Applied Catalysis B: Environmental 187 (2016) 249–258
30 40 50 60
a
(220)
(511)
(440)
(311)
(222)
(400)
(422)
c
b
(012)
(104)
(110)
(113)
(202)
(024)
(116)
(214)
(300)
(110)
(004)
(200)
(211)
Anatase
Rutile
Magnetite
Hematite
Maghemite
(101)
2ϴ30 40 50 60
Fig. 2. XRD patterns for (a) magnetite (b) calcined bare magnetite particles, and (c)
FP1. (For interpretation of the references to color in the text, the reader is referred
to the web version of this article.)
in our experiments, as this is the same wavelength used in low pres-
sure Hg UV lamps in water treatment plants. The suspension was
stirred at 100 rpm using a home-built overhead glass rod propeller.
After stirring in the dark for a minimum of 15 min, a sample was
withdrawn to measure the dark adsorption of TPA onto each cata-
lyst. Then, at specified intervals during illumination, 3 ml aliquots
of the stirred suspension were withdrawn using a 10 ml syringe
equipped with a 30 cm long plastic tube. The total volume extracted
from the starting 150 ml in any given experiment was less than
20 ml. Each 3 ml sample was passed through a 0.45 m pore size
filter to remove the magnetic particles. One ml of the filtered sam-
ple was transferred to a 20 ml volumetric flask and diluted with DI
water. To measure the hTPA concentration, a portion of this diluted
sample was transferred to a standard 1 cm cuvette and the fluores-
cence spectra were measured over the range of 350–500 nm. The
excitation frequency was set at 315 nm with a side entrance and exit
slit of 3 nm with 0.5 s integration time. TPA concentrations were
measured using HPLC at 238 nm with a mobile phase of acetoni-
trile (40% v/v) and water (60% v/v). All experiments were repeated
a minimum of three times.
For measuring the photocatalytic degradation of phenol, 0.075 g
of the magnetic particles was added to 150 ml of 10 mg/L phenol
(pH, 6.0 ± 0.2). The suspension was stirred in the dark for a mini-
mum of 15 min prior to the start of UV illumination and a sample
was withdrawn to measure the dark adsorption of phenol. The same
experimental protocol used for extracting TPA samples for analysis
was also used in the measurement of phenol. The phenol concen-
tration in solution after filtration was analyzed using HPLC with
mobile phase acetonitrile (20%v/v) and water (80% v/v) at 254 nm
wavelength.
2.5. Photodissolution experiments
For photodissolution experiment, after completion of the TPA
photocatalytic degradation experiments, the suspensions with pH
of 6.0-6.4 were kept in the dark without stirring for 30 min to allow
particle sedimentation. Then, a 10 ml aliquot of supernatant was
passed through a 0.22 m pore size nitrocellulose membrane to
remove any residual particles. The filtered samples were analyzed
for Fe, Ti and Si using the ICPMS.
3. Results and discussion
3.1. X-ray diffraction studies
The XRD patterns for the bare magnetic particles before and after
calcination, along with the sample FP1, are shown in Fig. 2. All peaks
for the magnetic particles before calcination (Fig. 2a) are assigned
30 40 50 60
a
b
c
d
f
e
2ϴ
TiO2
Magnetite
Hematite
30 40 50 60
Fig. 3. XRD pattern of (a) calcined magnetite (b) FP1, (c) FP2, (d) FP3, (e) FP4, and
(f) FP5.
to magnetite according to the International Centre for Diffraction
Data, Powder Diffraction File (ICCD, PDF 01-080-6402). A common
step in the generation of all P25-treated materials is calcination at
500 ◦C. Thus, for comparative purposes, the XRD pattern for the bare
magnetic particles that have undergone the calcination protocol
used in this work is provided in Fig. 2b. In Fig. 2b, peaks are assigned
to magnetite and hematite (ICCD, PDF 01-080-2377) and a trace
of maghemite. Calcination of the bare magnetic particles leads to
oxidation of magnetite to hematite, resulting in particles composed
of a mixture of magnetite and hematite. This calcination step also
leads to a color change from black to reddish brown.
In the XRD pattern for FP1 (Fig. 2c), peaks for magnetite,
hematite, and P25 are obtained. As found with the bare magnetic
particles calcined in air, calcination of FP1 samples also leads to
the conversion of the magnetite to hematite. Peaks at 30.02◦ and
33.12◦ are unique to magnetite and hematite, respectively, and
thus, the intensity of these two peaks can be used to monitor the
relative amount of each compound in the particles. For example,
the peak intensity ratio of 30.02◦:33.12◦ for FP1 (Fig. 2c) is higher
than the corresponding ratio for the calcined bare magnetic parti-
cles (Fig. 2b), showing that the P25 coating leads to a higher level of
oxidation of the magnetic particles than the O2 in the air. In addi-
tion, the redox reaction between the magnetic particles and P25
suggests that P25 must be in intimate contact with the magnetic
particles. Reduction of P25 is further supported by the change in
color of the particles from black to reddish brown [46]. This color
change is not due to diffusion of iron from the core to the P25. XPS
and EDX analysis shows that iron is not located at the surface of the
P25 particles (see Section 3.3).
The XRD patterns for various FPx samples are shown in Fig. 3.
The inset shows that the 30.02◦:33.12◦ peak ratio decreases with
higher P25 loading. Thus, there is an increase in the extent of oxi-
dation of magnetite to hematite with an increase in P25 loading.
To obtain an estimate of the extent of oxidation of magnetite to
hematite, we used the 30.02◦:35.6◦ and 33.12◦:35.6◦ peak ratios
(Fig. S2). The peak at 35.6◦ is a combination of the (3 1 1) and (1 1 0)
peaks of magnetite and hematite, respectively (Fig. 2). Given the
similar bulk density for these two iron oxides (hematite, 5.2 g cm−3
and magnetite 5.0 g cm−3), this peak provides a reasonable esti-
mate of the total iron oxide. The 30.02◦:35.6◦ peak ratios for 100%
magnetite (ICCD, PDF 01-080-6402) has a value of 0.3 and the cor-
responding 33.12◦:35.6◦ peak ratio for 100% hematite (ICCD, PDF
5. R.E. Kalan et al. / Applied Catalysis B: Environmental 187 (2016) 249–258 253
30 40 50 60
a
b
c
d
e
f
g
2ϴ
TiO2 Magnetite Maghemite
30 40 50 60
Fig. 4. XRD patterns for (a) magnetite (b) FS, (c) FS calcined, (d) FSP2, (e) FST, (f)
FSTP1, and (g) FSTP2.
01-080-2377) was 1.4. These values were used to convert the peak
ratio in the various samples to % composition. Fig. S2 shows FP1
that the relative amount of hematite increases only gradually with
each additional P25 loading in magnetic P25 (FPx) particles. This
shows that the surface coverage of the magnetic particle with P25
is almost complete at the 1:1 mass loading ratio.
An estimate of the relative loading of P25 on the magnetic parti-
cles is obtained from the XRD patterns shown in Fig. 3. Here the P25
peaks clearly increase in intensity relative to the iron oxide peaks
with high P25 loading. The ratio of the TiO2 (1 0 1) peak at 25.3◦ to
the total iron oxide (1 1 0) peak at 35.6◦ is linear with the starting
mass ratio of up to FP5 (Fig. S3). The small increase in magnetite to
hematite conversion above FP1, coupled with the linear increase in
P25 loading, shows that the thickness of the P25 coating increasing
with P25 loading up to FP5 (Fig. S3).
The XRD patterns for the magnetic particles before and after
coating with SiO2 are shown in Fig. 4a and b , respectively. All
peaks for the magnetic particles in Fig. 4a and b are assigned to
magnetite and show that these particles remain unchanged after
coating with SiO2. This is expected, given the amorphous structure
of the SiO2 sol-gel coating and that the coating procedure was per-
formed at room temperature. After calcination (Fig. 4c), weak peaks
at 23.8◦ and 26.1◦ show that a small amount of the magnetite is
converted to maghemite. There is little oxidation of the magnetic
particles, which is in contrast to what occurs upon calcination of
bare magnetite particles or the FPx samples. In essence, the SiO2
layer encapsulates the magnetic particles and inhibits reaction with
the oxygen in the air.
Fig. 4d is the XRD pattern for FSP2. There are small peaks due
to maghemite, but no peaks due to hematite; thus, the SiO2 layer
inhibits the redox reaction of the magnetite core with P25, since
P25 is not in direct contact with the underlying magnetite parti-
cles. It is noted that after rinsing the FSP2 samples in water, the
water turns into a white cloudy solution, indicating that some P25
is removed during this step. This is confirmed from the XRD data.
The peak intensity ratio of 25.3◦:35.6◦ for FSP2 (Fig. 4d) shows
that the P25 around the magnetic particles is 50% of that obtained
for FP2 (Fig. 3c). This shows that P25 does not adsorb strongly to
SiO2-coated magnetic particles. Recall that the samples FPx (x < 3)
show a linear growth with P25 loading (Fig. S3) and in this case, a
clear solution phase was obtained after the rinsing step.
To securely anchor the P25 on top of the silica coating, we intro-
duced a second TiO2 sol- gel layer. It has been reported that covalent
Si-O-Ti linkages form between the SiO2 and TiO2 layer leading to a
strongly bound TiO2 layer on the SiO2 [28]. Fig. 4e shows the XRD
1200 1100 1000 900 800 700 600
Wavenumber (cm-1)
Absorbance
a
b
c
d
e
Fig. 5. IR spectra of (a) calcined magnetite particles (b) FP1, (c) FS calcined, (d) FST,
and (e) FSTP1.
pattern for a FST sample. The weak broad (1 0 1) peak of TiO2 at
25.3◦ is observed due to a TiO2 thin layer around the magnetic par-
ticles. There are no hematite peaks after calcination because of the
presence of the SiO2 barrier. The FST particles are then calcined
with the P25 paste to obtain the FSTPx particles. Fig. 4f and g are
XRD patterns for FSTP1 and FSTP2, respectively, and show that the
ratio of P25 to magnetite for FSTP1 and FSTP2 samples are the same
as the corresponding FPx sample (Fig. 3b, c). Higher loadings of P25
were prepared (eg., FSTPx, x = 3,4,5) but these samples showed loss
of P25 during the rinse step.
Elemental analysis using the ICPMS for synthesized samples
showed agreement with XRD results in the total amount of Fe and
Ti in the samples. XRD data show that the amounts of TiO2 and
magnetic particles in the synthesized particles are within about
±10% of those determined by the ICPMS and the starting mass for-
mulation. ICPMS was also conducted to measure the presence of
dissolution products in the solution after UV illumination experi-
ments. In all cases, the photodissolution of Ti, Si, and Fe into solution
was found negligible at 0.005–0.04 mg/L, which translates to about
0.001–0.03% of the total mass of each sample (Table S3).
3.2. FT-IR analysis
Evidence of covalently attached SiO2 and TiO2 layers is provided
by IR spectral analysis. The IR spectrum of the calcined magnetic
particles (Fig. 5a) shows a broad Fe-O bulk mode near 560 cm−1
[47]. Fig. 5b is the spectrum for FP1, where the peak at 560 cm−1
is broader to the high wavenumber side, due to the presence of
the Ti-O bulk mode of P25. The spectrum of sample FS (Fig. 5c) has
a broad band at 1093 cm−1 due to a Si–O–Si bulk mode. Several
bands in the 650–600 cm−1 are assigned to the Si–O–Fe mode and
provide evidence of a covalently attached silica layer. For sample
FST (Fig. 5d), there is a tail on the high wavenumber side on the
broad band at 600 cm−1 showing the presence of a TiO2 coating.
This Ti-O mode is more intense in the spectrum for sample FSTP1
(Fig. 5e) due to the additional P25 on the surface.
3.3. XPS analysis
Fig. 6 shows the XPS spectrum for FP1. Peaks for aluminum and
carbon are from the substrate used for holding the powder samples.
Peaks due to Ti and O are obtained, along with a weak Fe peak that
could be either due to incomplete surface coverage or diffusion of Fe
6. 254 R.E. Kalan et al. / Applied Catalysis B: Environmental 187 (2016) 249–258
x 10
3
2
4
6
8
10
12
14
16
18
CPS
900 800 700 600 500 400 300 200 100 0
Binding Energy (eV)
Ti2p3/2
Ti2p1/2
O1s
C
Al
Al
Fe2p3/2
Fig. 6. XPS spectra for the FP1.
Table 2
Binding energy for Ti 2p3/2 and O1s.
Samples Ti 2p2/3 (eV) O1s (eV)
P25 460.5 532
FP1 458.0 532
FP2 457.4 532
FSTP1 459.2 532
FSTP2 459.4 532
from the core to the P25 surface [37]. However, for sample FP2, no
Fe peak is observed (Fig. S5). Therefore, it is likely that the Fe peak
obtained in the XPS spectrum of FP1 is due to incomplete coverage
and not diffusion of Fe from the core. XPS spectra for other samples
are shown in the SI section (Fig. S5–S8). In these spectra, there is no
Fe peak which indicates that the average thickness of the P25 layer
is >10 nm.
Table 2 shows the binding energy for the Ti2p3/2 and O1s peaks
for pure P25 and the various coated magnetic particles. The binding
energy for the Ti 2p3/2 peak is 460.5 eV for pure P25. For samples
FP1 and FP2, this binding energy shifts to lower energies, consis-
tent with the Ti being reduced which provides additional evidence
of a redox reaction between P25 and the magnetite particles. For
samples FSTP1 and FSTP2, the Ti2p3/2 binding energies are lower
than that for pure P25 and higher than that for FPx. However, the
XRD spectra show no conversion of magnetite to hematite and thus,
there is no reduction of the P25 in FSTPx particles to account for the
shift in binding energy. This shift in binding energy may arise from
direct contact of the TiO2 with the SiO2 layer [48]. Silica is more
electronegative than Ti and the substitution of Ti atoms by Si in
the Si-O-Ti bond decreases the coordination number around Ti and
leads to a shift in the Ti2p3/2 binding energy.
3.4. TEM analysis
The TEM images of bare magnetite particles and FP2 are shown
in Fig. 7a and b, respectively. The TEM in Fig. 7b shows magnetite
particles coated with clusters of P25. A TEM image of a single
particle of SiO2-coated magnetic particles (FS) in Fig. 7c shows a
thin layer of silica of a non-uniform thickness around the particle
(∼10–15 nm), which is in agreement with the XPS data.
Table 3
Specific surface area of Pure P25 and coated magnetic particles.
Photocatalyst Specific surface
area (m2
g−1
)
Estimated specific surface area normalized
with respect to P25 (m2
g−1
)
P25 59 (±0.5) 59
FP1 31 (±0.1) 62
FP2 41 (±0.2) 62
FP3 44 (±0.2) 58
FST 70 (±0.2) –
FSTP1 53 (±0.3) 36
FSTP2 61 (±0.2) 56
F3O4 9.5 (±0.1) –
Fig. 7d is the TEM image of a single particle of FST, and Fig. 7e
and f are TEM images of FSTPx. The TEM image of the FST single
particle in Fig. 7d shows a non-uniformTiO2 layer on top of the sil-
ica coating. The TiO2 sol-gel layer around the sample FST is thinner
than the P25 layer for samples FSTPx, as shown in Fig. 7e and f. This
is consistent with the XRD data (Fig. 4e) which shows that the TiO2
peak intensity in FST particles is less than 5% of TiO2 peak intensity
in FSTP1 particles. The thickness of the P25 layer around the mag-
netic particles shown by the TEM image in Fig. 7f is not uniform
and varies in the range of 20–100 nm. Furthermore, the P25 pri-
mary particles are in the form of clusters on the surface. It is noted
that P25 does not exist as primary particles but rather as a cluster
of primary particles of about 0.2 m diameter. This is true for all
fumed particles such as silica, titania and alumina. This is due to
sintering between particles that occurs during the transition from
the high temperature of synthesis and the cooling down process.
These clustered aggregates cannot be broken down into smaller
particles by physical processing. In addition these aggregates can
cluster into larger loosely associated agglomerates in solution. We
observe the same clusters of aggregates of P25 deposited on the
magnetic particles.
Based on the SEM images (Fig. S9) and EDX data (Table S5),
the Fe:Ti ratios are not uniformly distributed on the particle sur-
faces. Again this is consistent with the adsorption of P25 aggregates.
However, EDX analysis showed the presence of Ti with Fe in every
sample supporting the XPS data that Ti surface coverage is complete
and > 10 nm.
3.5. Surface area measurements
Table 3 shows the specific surface areas of coated magnetic par-
ticles obtained from BET analysis. For FPx particles, (x = 1–3), the
surface areas increase with the relative amount of P25. However,
the measured specific surface areas also include mass from the
magnetic core and thus, underestimates the specific surface area
of the P25. In the second column of Table 3, we have subtracted the
mass of the magnetic particles from the overall mass, assuming that
the starting formulation mass ratio of magnetic particles to P25 is
conserved in the final particles. This assumption is reasonable given
that the XRD and ICPMS data (Tables S2 and S4) shows that the
amount of TiO2 and magnetic particles in the synthesized samples
are within ±10% of the starting formulation. For the FPx samples,
after subtracting the mass contribution of the magnetic core from
the total mass, all samples show similar surface area with pure P25.
This again is reasonable given the adsorption of P25 aggregates on
the surface. Thus, the elevated temperature sintering of the P25 to
the magnetic core is not accompanied with any appreciable loss in
surface area of the P25 particles.
The FST surface area of 70 m2 g−1 is significantly higher than the
9.5 m2 g−1 measured for the magnetic particles. Thus, for the FST
sample, simple subtraction of the mass of the core when determin-
ing the surface area of the P25 is not valid. When the FST samples
are coated with P25 particles, the surface area decreases from 70
7. R.E. Kalan et al. / Applied Catalysis B: Environmental 187 (2016) 249–258 255
Fig. 7. TEM images of (a) magnetite, (b) FP2, (c) FS, (d) FST, (e) FSTP1, and (f) FSTP2.
to 53 and 61 m2 g−1 for FSTP1 and FSTP2, respectively. A drop in
surface area is expected because P25 particles have a lower sur-
face area (59 m2 g−1) than the underlying FST (70 m2 g−1). The TEM
images of FSTP1 and FSTP2 particles (Fig. 7e and f) show that the
P25 is a thick but loosely sintered cluster of P25 primary particles
around a magnetic core. Thus, we assume that there would be little
change in the surface area of the underlying FST surface with P25
loading. In this case, the overall measured surface area would be,
SA FSTPx =
(SAFST ∗ FSTmass) + (X ∗ P25mass)
Totalmass
(1)
where SA = surface area (m2 g−1), and x = calculated SA of the P25
layer in the FSTPx sample.
Using Eq. (1), we calculate a surface area of 56 m2 g−1 for the P25
layer in sample FSTP2, which is close to 59 m2 g−1 measured for P25
particles. Thus, we conclude that there is insignificant reduction in
surface area of the P25 coating in the FSTP2 sample. Details of the
surface area calculations are provided in the SI section.
3.6. Magnetic properties of photocatalyst
As shown in Fig. 8, pure magnetite, FSTP2, and FP2 have
magnetization saturation (Ms) values of 77, 40, and 10 emu g−1,
respectively. The Ms value for bare iron oxide magnetic particles is
similar to values reported in the literature [30,31]. The conversion
of magnetite to hematite in FP2 is consistent with the observed
magnetization decrease to 10 emu g−1. In contrast, FSTP2 exhibits
Ms value higher than FP2 but still lower than the bare magnetite,
which is attributed to magnetization screening provided by the
thick layer of P25 on the surface of magnetite.
3.7. Photocatalytic activity
The photogenerated electron-hole pair in the coated magnetic
particles decomposes water to produce HO• that was monitored
by hTPA formation. At the 83 mg/L initial concentration of TPA
used in this work, the generated hTPA reaches concentrations that
are sufficient to result in self quenching, leading to nonlinearity
in the fluorescence intensity with respect to hTPA concentration.
8. 256 R.E. Kalan et al. / Applied Catalysis B: Environmental 187 (2016) 249–258
-100
-80
-60
-40
-20
0
20
40
60
80
100
-100000 -50000 0 50000 100000
MagnaƟzaƟon(emu/g)
Field (Oe)
a) Fe3O4
b) FSTP2
c) FP2
a
b
c
a) Fe3O4
Fig. 8. The room-temperature magnetization curves of (a) magnetite, (b) FSTP2, and
(c) FP2.
0
1
2
3
4
5
6
7
8
0 5 10 15 20 25 30 35 40
[hTPA](mg/L)
Time (min)
P25
FSTP2
FSTP1
FP2
FP1
FST
F
FS
UV
b
a
c
0
0.2
0.4
0.6
0.8
1
0 10 20 30
[TPA]/[TPA]0
Time (min)
FSTP2
P25
-1.2
-1
-0.8
-0.6
-0.4
-0.2
0
0 10 20 30 40
ln([TPA]/[TPA]0)
Time (min)
P25
FSTP2
Fig. 9. (a) hTPA concentration versus UV radiation time for all photocatalyst
(0.5 g/L), (b) TPA relative concentration versus UV irradiation time, and (c) TPA
degradation rate (initial TPA concentration = 83 mg/L and all photocatalysts con-
centration = 0.5 g/L).
At a twenty-fold dilution of hTPA, self quenching is not observed
and a linear relationship exists between hTPA concentration and
fluorescence intensity.
Fig. 9a shows the hTPA concentration versus irradiation time for
each sample. In all cases, the hTPA formation is linear with respect
to time [49–52]. In several control experiments (i.e., UV irradiation
of the TPA solution containing no particles, bare magnetic parti-
cles, or FS particles) there was negligible reaction, showing that UV
irradiations under conditions of no P25 present does not produce
HO•.
A stated goal of this work was to produce a photocatalyst with
magnetic properties that had equal photocatalytic degradation
rates to that of P25 particles. Yu et. al. [7], reported photocatalytic
degradation rates for sol-gel TiO2- and SiO2-coated magnetic parti-
cles (similar to FST particles in this study) equivalent to that of P25.
Our experiments showed that the activity of our FST particles with
respect to HO• production was 5% of P25 particles, which is just
above what was obtained for UV illumination without any photo-
catalyst present (Fig. 9a). In contrast, the P25-coated particles (i.e.,
FPx and FSTPx) had higher photocatalytic rates, with FSTPx parti-
cles showing more activity compared to FPx particles. The higher
activity in FSTPx is most likely due to the insulative effect of SiO2
coatings.
The initial photocatalytic degradation of TPA follows pseudo
first-order kinetics [51,52] and the formation of hTPA follows
pseudo zero-order kinetics [43,49,51–53]. From this, the initial rate
constants for hTPA, and hence HO•, formation by P25 and FSTP2
are 0.234 ± 0.177 and 0.112 ± 0.051 M min−1, respectively on a total
mass of catalyst basis (Fig. 9a). The FSTP2 samples tested with the
same particles twice resulted in the same OH radical yield. Dark
adsorption was minimal (∼3.0%) for TPA and phenol on both P25
and FSTP2 after a 15 min incubation and this value did not change
after a 30 min stirring. Fig. 9b shows TPA photocatalytic degradation
versus irradiation time using P25 and FSTP2 catalysts. After a 30 min
reaction time, 38% of the TPA is decomposed by P25 compared to
20% for FSTP2. Using pseudo-first order reaction kinetics for TPA
photocatalytic degradation [36,54], rate constants (Fig. 9c) for TPA
photocatalytic degradation by P25 and FSTP2 are 0.0152 ± 0.003
and 0.0146 ± 0.005 min−1, respectively.
The photocatalytic degradation of phenol by P25 and FSTP2
particles were also studied (Fig. 10a). After 30 min of irradia-
tion, more than 97% and 88% of phenol is degraded by P25
and FSTP2, respectively. Photocatalytic degradation of phenol fol-
lows first order reaction kinetics [42,55], and the corresponding
first-order rate constants by P25 and FSTP2 are 0.087 ± 0.02 and
0.067 ± 0.03 min−1, respectively (Fig. 10b).
It is noted that we have reported decomposition based on total
mass of the photocatalyst and that a significant fraction of this
mass comes for the magnetic core. When we calculate the rates
on a per P25 mass, instead of total mass, the rates between P25 and
FSTP2 are similar. The values obtained for TPA photocatalytic degra-
dation are 0.0152 ± 0.003 min−1 for P25 and 0.0144 ± 0.007 min−1
for FSTP2. These rate constants for phenol photocatalytic degrada-
tion are 0.09 ± 0.02 min−1 for P25 and 0.10 ± 0.04 min−1 for FSTP2.
Since the effective surface area of the P25 aggregates on the mag-
netic particles is similar to P25 suspensions it is reasonable that
the P25 aggregates in the solution would have similar mass trans-
port behavior as the same aggregates deposited on the magnetic
particles. This results in similar rate constants based on amount of
P25 on the coated magnetic particles and P25 for the photocatalytic
degradation of TPA and phenol. We note that there could be differ-
ences in the level of illumination for magnetic particles and P25
suspension and the impact of this on the measured rate constants
are not known.
4. Conclusions
The key development of this study was to use underlying SiO2
layer coating magnetite particles followed by a TiO2 layer applied,
using the sol-gel technique, to effectively anchor the P25 to the
particles. This resulted in a 1:2 mass ratio of P25 to the magnetic
10. 258 R.E. Kalan et al. / Applied Catalysis B: Environmental 187 (2016) 249–258
[42] J. Ryu, W. Choi, Environ. Sci. Technol. 42 (2008) 294–300.
[43] K.-I. Ishibashi, A. Fujishima, T. Watanabe, K. Hashimoto, Electrochem.
Commun. 2 (2000) 207–210.
[44] C.G. Hatchard, C.A. Parker, Proc. R. Soc. Lond. Ser. A Math. Phys. Sci. 235 (1956)
518–536.
[45] Z. Pan, E.A. Stemmler, H.J. Cho, W. Fan, L.A. LeBlanc, H.H. Patterson, A.
Amirbahman, J. Hazard. Mater. 279 (2014) 17–25.
[46] J.-Y. Shin, J.H. Joo, D. Samuelis, J. Maier, Chem. Mater. 24 (2012) 543–551.
[47] A.L. Andrade, D.M. Souza, M.C. Pereira, J.D. Fabris, R.Z. Domingues, Cerâmica
55 (2009) 420–424.
[48] H. Cao, P. Du, L. Song, J. Xiong, J. Yang, T. Xing, X. Liu, R. Wu, M. Wang, X. Shao,
Mater. Res. Bull. 48 (2013) 4673–4678.
[49] J. Yu, W. Wang, B. Cheng, B.-L. Su, J. Phys. Chem. C 113 (2009) 6743–6750.
[50] B. Tryba, M. Toyoda, A.W. Morawski, R. Nonaka, M. Inagaki, Appl. Catal. B:
Environ. 71 (2007) 163–168.
[51] U. ˇCernigoj, M. Kete, U.L. Stangar, Catal. Today 151 (2010) 46–52.
[52] M. Kete, E. Pavlica, F. Fresno, G. Bratina, U.L. ˇStangar, Environ. Sci. Pollut. Res.
21 (2014) 11238–11249.
[53] Q. Xiao, Z. Si, J. Zhang, C. Xiao, X. Tan, J. Hazard. Mater. 150 (2008) 62–67.
[54] R. Thiruvenkatachari, T.O. Kwon, J.C. Jun, S. Balaji, M. Matheswaran, I.S. Moon,
J. Hazard. Mater. 142 (2007) 308–314.
[55] B. Tryba, A.W. Morawski, M. Inagaki, M. Toyoda, Appl. Catal. B: Environ. 63
(2006) 215–221.
[56] K. Linden, G. Shin, Sobsey, Water Sci. Technol. 43 (2001) 171.