Paulo José Pereira de Oliveira; Fabielle Castelan Marques; Arlan da Silva Gonçalves; Greice Kelly dos Santos Brito; Enzo Victorio Andrade; Marcos Pedro Dalmaso Pinto
Abstract
Global warming has generated great concern worldwide. One way to control this problem is to use clean renewable energy new sources. Among the energy sources, we can mention hydrogen gas, produced by water photocatalysis by mean of a semiconductor material. In this work, we report a study about band gap ...
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Global warming has generated great concern worldwide. One way to control this problem is to use clean renewable energy new sources. Among the energy sources, we can mention hydrogen gas, produced by water photocatalysis by mean of a semiconductor material. In this work, we report a study about band gap and absorption spectra by mean of the density functional theory of the anatase allotropic form of titanium dioxide doped with Ruthenium. The results indicated systematic decrease of the band gap and increase of the absorbance at the visible region with the increase of the amount of dopant.
Giulia Ognibene; Gianluca Cicala; Maria Elena Fragalà
Abstract
ZnO nanorods (ZnO) are grown by Chemical Bath Deposition on microfiltration polyetheresulphone (PES) water membranes in order to combine photocatalytic properties of zinc oxide to adsorption properties of membranes. Degradation of a model dye (methylene blue, MB) dispersed in water is promoted by exposition ...
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ZnO nanorods (ZnO) are grown by Chemical Bath Deposition on microfiltration polyetheresulphone (PES) water membranes in order to combine photocatalytic properties of zinc oxide to adsorption properties of membranes. Degradation of a model dye (methylene blue, MB) dispersed in water is promoted by exposition of multifunctional ZnO/PES membranes to UV and solar light: in fact, ZnO decorated membrane ensures generation of reactive oxygen species (ROS) that degrade the organic pollutants dispersed in water. ZnO degradation promoted by UV irradiation is detectable by anionic meso-tetrakis(4-sulfonatophenyl) porphyrin (H2TPPS 4- ) that is used as effective molecular probe to sense the presence of Zn 2+ ions due to photocatalytic leaching. Copyright © VBRI Press.
Elias E. Elemike; Saiyed Tanzim; Anthony C. Ekennia; Damian C. Onwudiwe
Abstract
The green synthesis of silver nanoparticles using Cyamopsis tetragonoloba plant extract and their photocatalytic and antibacterial properties is reported. Three precursor concentrations of 1 mM, 2 mM and 5 mM were used, and at two different ratios of 1:5 and 1:10 plant extract to the precursor. The formation ...
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The green synthesis of silver nanoparticles using Cyamopsis tetragonoloba plant extract and their photocatalytic and antibacterial properties is reported. Three precursor concentrations of 1 mM, 2 mM and 5 mM were used, and at two different ratios of 1:5 and 1:10 plant extract to the precursor. The formation of the nanoparticles was followed by the periodic study of surface plasmon resonance using the UV-visible spectroscopy, which revealed the formation of nanoparticles with regular bands after 45 min. of reaction. Fourier transform infrared spectroscopy was used to study the functional groups present in the plant biomolecules which aided the reduction and stabilization of the nanoparticles. Transmission electron microscopy analysis and X-ray diffraction pattern showed the particle sizes and crystalline structures, while the zeta potential values indicated the stability of the nanoparticles. The 5 mM concentration gave the largest particle sizes of about 12.90 nm and the most stable particles. The photocatalytic properties of the particles studied using Methyl red showed a low efficiency of 17.85% degradation achieved under 2 h. The antibacterial potency of the nanoparticles was screened against some gram-negative and gram-positive bacteria. The results showed that the nanoparticles have good antibacterial activities.
Yidi Wang; Pui Fai NG; Bin Fei
Abstract
Hybrid organic–inorganic perovskite materials have attracted a lot of attention with their facile synthesis process and high efficiency of light absorption. However, poor stability is always a big barrier to commercial development. In this study, a new kind of organic perovskites MA0.6(AA)0.4PbBr3 ...
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Hybrid organic–inorganic perovskite materials have attracted a lot of attention with their facile synthesis process and high efficiency of light absorption. However, poor stability is always a big barrier to commercial development. In this study, a new kind of organic perovskites MA0.6(AA)0.4PbBr3 (AM-PE), which harnesses aniline as a replacement of conventionally used methylamine, was synthesized to increase the stability of MAPbBr3 (M-PE). The decomposition process of MAPbBr3 in acetone was investigated. Smaller PbBr2 particles were formed in the decomposition process, causing the change of photoluminescence emission wavelength from 540 nm to 610 nm. The photocatalysis and photoluminescence properties of M-PE and AM-PE were also compared. As a result, the introduction of aniline reduced the decomposition rate of AM-PE significantly and showed twice the catalysis efficiency of M-PE in the degradation of organic dye - malachite green.
Yanyu Zhang; Palas Baran Pati; Haining Tian
Abstract
Organic semiconducting polymer nano-particles, as nano-photocatalysts for light driven proton reduction, have been prepared by using Triton X-100 as surfactant. The nano-photocatalysts prepared by Triton X-100 showed well dispersibility in water and no precipitation observed after photocatalysis. The ...
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Organic semiconducting polymer nano-particles, as nano-photocatalysts for light driven proton reduction, have been prepared by using Triton X-100 as surfactant. The nano-photocatalysts prepared by Triton X-100 showed well dispersibility in water and no precipitation observed after photocatalysis. The effect of molecular weight and concentration on photocatalysis has been investigated, indicating that the particle size shows significant influence on photocatalytic performance. The sample with 100 µg/ml photocatalysts gave the best hydrogen evolution amount of 0.4 µmol/ml and apparent quantum yield of 1.3% at 450 nm.
Pardeep Singh; Sourav Gautam; Pooja Shandilya; Bhanu Priya; Virender P. Singh; Pankaj Raizada
Abstract
The supported photocatalysis is emerging as an effective technology to overcome of inherent drawbacks of bare magnetic photocatalysts. Herein, ZnFe2O4 was immobilized over graphene sand composite (GSC) and bentonite (BT) to report ZnFe2O4/GSC and ZnFe2O4/BT photocatalyst. The size of ZnFe2O4/GSC and ...
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The supported photocatalysis is emerging as an effective technology to overcome of inherent drawbacks of bare magnetic photocatalysts. Herein, ZnFe2O4 was immobilized over graphene sand composite (GSC) and bentonite (BT) to report ZnFe2O4/GSC and ZnFe2O4/BT photocatalyst. The size of ZnFe2O4/GSC and ZnFe2O4/BT was obtained as 100 and 50 nm, respectively. Both photocatalysts exhibited band gap of 1.95 eV. ZnFe2O4/GSC and ZnFe2O4/BT had BET surface area of 15.6 and 14.5 cm 2 , respectively. The appearance of D and G band in Raman spectra indicated the formation of graphene sand composites. The superparamagnetic property of photocatalyst resulted in quick separation photocatalyst form reaction solution. The adsorption and photocatalytic capability of ZnFe2O4/GSC and ZnFe2O4/BT was evaluated for photo-mineralization of ampicillin and oxytetracycline antibiotics. The adsorption process showed significant effect on mineralization of selected antibiotics. Simultaneous adsorption and degradation (A+P) process was highly effective for antibiotic degradation. More than 90% of antibiotic mineralization was obtained in 10 hours. The power law model authorized the complex nature of degradation process. Magnetically recoverable photocatalyst exhibited significant recycling efficiency due to easier recovery of photocatalysts.
Jaspal Singh; Kavita Sahu; Sini Kuriakose; Nishant Tripathi; D. K. Avasthi; Satyabrata Mohapatra
Abstract
Nanostructured TiO2 thin films with highly enhanced photocatalytic activity were prepared by atom beam sputtering technique. The effects of thermal annealing on the structural, morphological and photocatalytic properties of TiO2 thin films were investigated using X-ray diffraction, atomic force microscopy, ...
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Nanostructured TiO2 thin films with highly enhanced photocatalytic activity were prepared by atom beam sputtering technique. The effects of thermal annealing on the structural, morphological and photocatalytic properties of TiO2 thin films were investigated using X-ray diffraction, atomic force microscopy, field emission scanning electron microscopy, Raman spectroscopy and UV-visible absorption spectroscopy. X-ray diffraction studies showed that the as-deposited TiO2 thin films made up of anatase TiO2 nanoparticles transformed into anatase/ rutile mixed-phase TiO2 nanoparticles upon annealing. Field emission scanning electron microscopy and atomic force microscopy studies revealed growth of TiO2 nanoparticles from 16 nm to 29 nm upon annealing at 600 o C. The photocatalytic activities of the nanostructured TiO2 thin films were studied by monitoring photocatalytic degradation of methylene blue in water. Our results showed that the as-deposited nanostructured TiO2 thin films exhibited highly enhanced photocatalytic efficiency as compared to the annealed samples. The mechanism underlying the enhanced photocatalytic activity of nanostructured TiO2 thin film is tentatively proposed.
M. Mzoughi; William. W. Anku; Samuel O. B. Oppong; Sudheesh K. Shukla; Eric S. Agorku; Penny P. Govender
Abstract
Purification of industrial wastewater from dyes receiving increasing attentions. The aim of the present manuscript was to fabricate graphene based nanocomposites using a homogeneous and facile approach. Co-precipitation method was used to synthesize zirconium oxide (ZrO2) and neodymium doped ZrO2-graphene ...
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Purification of industrial wastewater from dyes receiving increasing attentions. The aim of the present manuscript was to fabricate graphene based nanocomposites using a homogeneous and facile approach. Co-precipitation method was used to synthesize zirconium oxide (ZrO2) and neodymium doped ZrO2-graphene oxide (Nd-ZrO2-GO) nanocomposites with varying weight percent concentrations of neodymium to investigate the increasing photocatalytic activity. The Nd-ZrO2-GO catalysts were characterized using X-ray powder diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (SEM), and ultra violet-visible (UV-vis)-spectroscopy to evaluate their optical, morphological and structural properties respectively. The photocatalytic degradation potential of the nanocatalyst was assessed by the degradation of Eosin Y dye in aqueous solution under simulated solar light irradiation. The Nd-ZrO2-GO was observed to have higher photocatalytic degradation potential than the bare ZrO2. The most efficient photocatalyst for the degradation of Eosin Y dye was 0.3 % Nd-ZrO2-GO with about 80 % efficiency within 180 min and a Ka value of 4.19 x 10 -3 . Nd-ZrO2-GO catalyst would be considered as efficient photocatalyst to degrade the industrial dyes (Eosin Y) avoiding the dreary filtration steps.
Richard Dvorsky
Abstract
A new preparation method of lamellar core-shell ZnO-(Si)-ZnO nanostructures with high specific surface area and high photocatalytic efficiency is presented in this article. This novel method is based on the application of controlled vacuum sublimation of the frozen liquid dispersion of silicon nanoparticles ...
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A new preparation method of lamellar core-shell ZnO-(Si)-ZnO nanostructures with high specific surface area and high photocatalytic efficiency is presented in this article. This novel method is based on the application of controlled vacuum sublimation of the frozen liquid dispersion of silicon nanoparticles which were prepared by using the "top-down" process in cavitation Water Jet Mill disintegrator. The particle size of thus disintegrated silicon nanoparticles was measured by dynamic light scattering (DLS). Final product ZnO-(Si)-ZnO was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and amount of ZnO and Si was measured by energy dispersive x-ray spectroscopy (EDAX). Specific surface area was obtained from Brunauer-Emmett-Teller analysis (BET). The photocatalytic activity of ZnO-(Si)-ZnO nanostructure was verified by the decomposition of methylene blue (MB) solution. The Final nanomaterial shows a relatively high specific surface area of 134 m2/g and significantly higher photocatalytic activity compared to standard TiO2 (Degussa P25). Such procedure based on the controlled vacuum sublimation of frozen liquid of suitable metal salts could be a promising method for obtaining photocatalytic nanomaterials with higher specific surface area.
Suraksha Rasal; Sunita Jadhav;Pawan K. Khanna; Priyesh V. More; Chaitanya Hiragond
Abstract
ZnO/CdS core-shell hetero nanostructures with different shell thickness have been successfully developed by a solution chemistry method employing rapid homogenization concept. The obtained core/shell nanoparticles were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy ...
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ZnO/CdS core-shell hetero nanostructures with different shell thickness have been successfully developed by a solution chemistry method employing rapid homogenization concept. The obtained core/shell nanoparticles were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray analysis (EDX), FTIR, Raman, photoluminescence (PL), and UV-visible spectroscopy. All analytical and spectroscopic tools supported the formation of CdS shell over ZnO core. ZnO/CdS core-shell nanostructures were evaluated for their photocatalytic activity against methylene blue (MB), a common industrial water pollutant. It was observed that the ZnO/CdS core-shell nanostructures can effectively function as a photocatalyst under both UV and sunlight for degradation of MB. It was also observed that the degradation of MB was higher from core/shell nanostructures than the physical mixture of ZnO-CdS which was prepared separately.
Pankaj Raizda; Sourav Gautam; Bhanu Priya; Pardeep Singh
Abstract
The study investigates photocatalytic activity of hydroxyapatite supported BiOCl (BiOCl/HA) in the presence of H2O2. BiOCl/HA was prepared by simple hydrolysis method. BiOCl/HA was characterized using scanning electron microscopy (SEM), tunneling electron microscopy (TEM), X- ray diffraction (XRD), energy ...
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The study investigates photocatalytic activity of hydroxyapatite supported BiOCl (BiOCl/HA) in the presence of H2O2. BiOCl/HA was prepared by simple hydrolysis method. BiOCl/HA was characterized using scanning electron microscopy (SEM), tunneling electron microscopy (TEM), X- ray diffraction (XRD), energy diffraction X-ray (EDX), Fourier transform infrared spectroscopy (FTIR) and UV-visible (UV-vis)analysis. SEM results confirmed the dispersion of BiOCl onto hydroxyapatite. BiOCl/HA exhibited irregular pleats-like structure having average size of 80 nm. The band gap of BiOCl/HA was found to be 3.42 eV. The solar light was used as radiation source during photocatalysis. Both H2O2 and BiOCl/HA had synergistic effect on oxytetracycline removal. The simultaneous adsorption and photocatalysis (A+P) was most efficient process for OTC removal. The photocatalytic degradation of oxytetracycline obeyed pseudo first order kinetics. The effect of process parameters catalyst loading, H2O2 concentration, pH and OTC concentration was investigated on photocatalysis. The oxidative removal occurred through hydroxyl radical formation. BiOCl exhibited significant recycle efficiency due to easier separation and stability in reaction solution. Solar/H2O2/BiOCl/HA displayed excellent photocatalytic property for degradation of OTC from aqueous solution.
Atul B. Lavand; Yuvraj S. Malghe
Abstract
Nanosized bare, C and N doped as well as C, N co-doped ZnO nanopowders were prepared using microemulsion method. Synthesized powders were characterized using X-ray diffraction(XRD), Fourier transform infrared spectrophotometer (FTIR), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy ...
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Nanosized bare, C and N doped as well as C, N co-doped ZnO nanopowders were prepared using microemulsion method. Synthesized powders were characterized using X-ray diffraction(XRD), Fourier transform infrared spectrophotometer (FTIR), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), CHNS analyzer, photoluminescence spectrophotometer and UV-visible spectrophotometer. XRD study shows that C, N co-doped ZnO have hexagonal wurtzite structure. UV-visible spectral study reveals that C and N co-doping improves photo absorption capacity in visible region. Visible light photocatalytic degradation of malachite green was carried out using nanosized bare, C doped and C, N co-doped ZnO. C, N co-doped ZnO exhibits better visible light photocatalytic activity as compared to pure and C doped ZnO. Also the photocatalyst prepared is stable and can be reused repeatedly.
Yuvraj S. Malghe; Atul B. Lavand
Abstract
C/ZnO/CdS nanocomposite was synthesized using microemulsion method. Thermal stability of precursor was studied with TG and DTA techniques. Structural and optical properties of composite were studied using various characterization techniques like X-ray diffraction (XRD), fourier transform infrared spectroscopy ...
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C/ZnO/CdS nanocomposite was synthesized using microemulsion method. Thermal stability of precursor was studied with TG and DTA techniques. Structural and optical properties of composite were studied using various characterization techniques like X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), energy dispersive x-ray spectroscopy (EDX), transmission electron microscopy (TEM) and UV-visible absorption spectroscopy and photoluminescence spectroscopy. XRD study indicates that ZnO and CdS are having wurtzite and cubic phase in the composite sample. SEM and TEM study indicates formation of CdS nanospheres on ZnO nanorods. C doping and CdS coupling are responsible for red shift and shifting of absorption edge of ZnO from UV to visible region. C/ZnO/CdS nanocomposite exhibits better visible light photocatalytic activity for degradation of methylene blue (MB). Stability of photocatalyst was studied using recovered photocatalyst up to third cycle and it was found that photocatalyst prepared in the present work is stable and reusable.
Sini Kuriakose; Biswarup Satpati; Satyabrata Mohapatra
Abstract
ZnO nanostructures were synthesized by a facile wet chemical method using water, ethanol and propanol as solvents. X-ray diffraction, field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) have been used to study the structural properties of the synthesized ZnO ...
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ZnO nanostructures were synthesized by a facile wet chemical method using water, ethanol and propanol as solvents. X-ray diffraction, field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) have been used to study the structural properties of the synthesized ZnO nanostructures, while their optical properties have been studied using UV-visible absorption spectroscopy and Raman spectroscopy. The photocatalytic activities of the as-synthesized ZnO nanostructures were evaluated by monitoring sunlight driven photocatalytic degradation of methylene blue (MB) and methyl orange (MO) dyes in water and it was observed that ZnO nanostructures prepared using propanol as a solvent exhibit highly enhanced photocatalytic activity as compared to those prepared using other solvents. The mechanism underlying the photocatalytic activity of ZnO nanostructures towards photocatalytic degradation of dyes is proposed. We attribute the highly enhanced photocatalytic activity of ZnO nanostructures prepared in propanol to the high surface area of nanosheets-like structures formed, which lead to enhanced adsorption of dye molecules resulting in efficient photocatalytic degradation of dyes upon sunlight irradiation.
Jaspal Singh; Satyabrata Mohapatra
Abstract
Nanostructures of TiO2 were synthesized by a facile sol-gel method using pentanol as solvent. The effects of thermal annealing on the structural, optical and photocatalytic properties of as-synthesized TiO2 nanostructures have been studied using X-ray diffraction (XRD), atomic force microscopy (AFM), ...
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Nanostructures of TiO2 were synthesized by a facile sol-gel method using pentanol as solvent. The effects of thermal annealing on the structural, optical and photocatalytic properties of as-synthesized TiO2 nanostructures have been studied using X-ray diffraction (XRD), atomic force microscopy (AFM), Raman spectroscopy and UV-visible absorption spectroscopy. XRD and Raman spectroscopy results revealed that the synthesized TiO2 nanostructures exist in anatase phase for annealing at temperatures up to 300 o C, while annealing at 600 o C led to the formation of TiO2 nanostructures in anatase/rutile mixed-phase. AFM studies revealed the presence of TiO2 nanorods, which showed a small decrease in aspect ratio upon annealing. The photocatalytic activity of nanostructured TiO2 samples was evaluated through sun light driven degradation of methylene blue (MB) dye in water. TiO2 nanorods in anatase/rutile mixed-phase in the sample annealed at 600 o C were found to exhibit the highest photocatalytic activity towards degradation of MB dye. The mechanism underlying the enhanced photocatalytic activity of TiO2 nanostructures in anatase/rutile mixed-phase is tentatively proposed.
Sini Kuriakose; Biswarup Satpati; Satyabrata Mohapatra
Abstract
Highly photocatalytically active nanodisks of ZnO and Co doped ZnO were synthesized by a facile wet chemical method. The structural, optical and photocatalytic properties of ZnO and Co doped ZnO nanodisks were studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), atomic ...
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Highly photocatalytically active nanodisks of ZnO and Co doped ZnO were synthesized by a facile wet chemical method. The structural, optical and photocatalytic properties of ZnO and Co doped ZnO nanodisks were studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), transmission electron microscopy (TEM), Raman spectroscopy and UV-visible absorption spectroscopy. FESEM, AFM and TEM studies revealed the presence of ZnO nanodisks. Sun light driven degradation of aqueous methyl orange (MO) dye was used for evaluating the photocatalytic activity of as-synthesized ZnO and Co doped ZnO nanodisks. Co doped ZnO nanodisks showed very high photocatalytic efficiency and lead to almost complete degradation of MO dye in just 8 minutes. A tentative mechanism of the photocatalytic degradation of MO by Co doped ZnO nanodisks is proposed. We attribute the enhanced photocatalytic activity of Co doped ZnO nanodisks to their high specific surface area and efficient charge carrier separation due Co doping, which improves suppression of recombination of photogenerated electrons and holes. Development of sun light active highly efficient and stable photocatalysts is very promising for environmental remediation leading to safe and clean water.
P. Muthirulan; C. K. N. Devi; M. M. Sundaram
Abstract
Simple and proficient methodology has been proposed for the preparation of hybrid photocatalyst based on titanium dioxide (TiO2)-graphene (GR) nanocomposite for acid orange 7 (AO7) dye degradation under UV irradiation. High Resolution Transmission Electron Microscopy (HRTEM) and Scanning Electron Microscopy ...
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Simple and proficient methodology has been proposed for the preparation of hybrid photocatalyst based on titanium dioxide (TiO2)-graphene (GR) nanocomposite for acid orange 7 (AO7) dye degradation under UV irradiation. High Resolution Transmission Electron Microscopy (HRTEM) and Scanning Electron Microscopy (SEM) studies revealed that TiO2 nanoparticles were uniformly dispersed on GR surface. TiO2-GR hybrid nanocomposite has also been characterized by Ultraviolet Diffusive Reflectance Spectroscopy (UV-DRS), Raman spectroscopy and X-ray diffraction (XRD) studies. Electrochemical Impedance spectroscopy (EIS) measurement revealed that the incorporation of GR with TiO2 nanoparticles significantly enhanced the electrical conductivity.The peak intensity of PL spectra of GR containing catalysts are lower than that of pristine TiO2, indicating that the electron–hole recombination rate of self-trapped excitations in TiO2 is reduced by the introduction of GR. The photocatalytic degradation measurements demonstrated that the TiO2-GR composites exhibited an enhanced photocatalytic activity for AO7 degradationunder UV irradiation compared to pure TiO2. This may due to greater adsorptivity ofdyes, extended light absorption and increased charge separation efficiency due to excellent electricalproperties of graphene and the large surface contact between graphene and TiO2 nanoparticles. Therefore, the TiO2-GR composites can be widely used as a ternary composite photocatalyst for treating the organic contaminant in the field of environmental protection.
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