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1.
A novel heterogeneous composite material based on reduced graphene oxide (rGO) and bismuth vanadate (BiVO4) was prepared and characterized by various techniques such as powder XRD, HRTEM, EADX, UV–Vis‐DRS, FT‐IR, Raman, BET and XPS analyses. The characterization results reveal that the rGO well decorated by BiVO4. The electrochemical impedance spectroscopy (EIS) shows the increasing of charge transfer of rGO/BiVO4 in presence of light irradiation. In this research, the pure BiVO4 and rGO/BiVO4 composite have been explored for photocatalytic reduction of nitroarenes. Among the prepared nanocomposites, rGO loaded with 10% BiVO4 catalyst (noted as rGO/BiVO4–10%) shows the best performance for the photo‐reduction of various nitroaromatic molecules to their corresponding amine compounds under visible‐light irradiation at room temperature. The catalyst exhibited in particular excellent photocatalytic activity for the conversion of 1,4‐dinitrobenzene to 4‐nitroanilline (100% conversion) in 20 min, 4‐chloronitrobenzene to 4‐chloroaniline and 2‐nitrophenol to 2‐aminophenol (100% conversion) in only 30 min. In addition, the conversion of 4‐bromonitrobenzene, 4‐iodonitrobenzene to their corresponding amine compounds (100% conversion) was achieved in 60 min. The catalyst was recovered for several times and reused without decreasing of its efficiency.  相似文献   

2.
The nanocomposites of titania coupled with graphene oxide (GO) and reduced graphene oxide (rGO), respectively, were prepared by homogeneous hydrolysis with urea. Graphene was obtained by effect of high‐intensity cavitation field on natural graphite in the presence of strong aprotic solvents in pressurized ultrasonic reactor. The morphology of TiO2–GO and TiO2–rGO composites was assessed by scanning electron microscopy and atomic force microscopy. The nitrogen adsorption–desorption was used for determination of surface area (BET) and porosity. Raman and IR spectroscopy were used for qualitative analysis and diffuse reflectance spectroscopy was employed to estimate band‐gap energies. Further enhancement of the photocatalytic activity was attained by codoping of composites with noble metals—Au, Pd and Pt. The photocatalytic activity of TiO2–GO and TiO2–rGO were assessed by photocatalytic decomposition of Orange II dye in an aqueous slurry under UV and visible light irradiation. The photocatalytic activity of noble metals codoped samples was determined with decomposition of Reactive Black 5 azo dye.  相似文献   

3.
In this paper, magnetic nanocomposites are synthesized by loading reduced graphene oxide (RG) with two components of nanoparticles consisting of titanium dioxide (TiO2) and magnetite (Fe3O4) with varying amounts. The structural and magnetic features of the prepared composite photocatalysts were investigated by powder X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR), transmission electron microscopy (TEM), UV–vis diffuse reflectance spectra (UV–vis/DRS), Raman and vibrating sample magnetometer (VSM). The resulting TiO2/magnetite reduced graphene oxide (MRGT) composite demonstrated intrinsic visible light photocatalytic activity, on degradation of tartrazine (TZ) dye from a synthetic aqueous solution. Specifically, it exhibits higher photocatalytic activity than magnetite reduced graphene oxide (MRG) and TiO2 nanoparticles. The photocatalytic degradation of TZ dye when using MRG and TiO2 for 3 h under visible light was 35% and 10% respectively, whereas for MRGT it was more than 95%. The higher photocatalytic efficiency of MRGT is due to the existence of reduced graphene oxide and magnetite which enhances the photocatalytic efficiency of the composite in visible light towards the degradation of harmful soluble azo dye (tartrazine).  相似文献   

4.
Metal oxide frame works along with carbon materials have been attracting tremendous attention of researches as the potential materials for energy and environmental remediation. In the present work heterostructures of (ZnO/CuO)/rGO ternary nanocomposites were synthesized by solid-state method. The crystalline structure of the nanoparticles was obtained from the XRD analysis. Optical band gap of the ZnO nanoparticles (3.1 eV) is tuned to 2.8 eV in the synthesized (ZnO/CuO)/rGO ternary nanocomposites. Field emission scanning electron microscope images of the (ZnO/CuO)/rGO ternary nanocomposites revealed formation of well-developed flowers like morphology of (ZnO/CuO) nanoparticles on rGO sheets. Photoluminescence spectroscopy analysis of (ZnO/CuO)/rGO ternary nanocomposites show enhancement in the electron-hole pair separation and thereby diminishing electron-hole pairs recombination rates effectively. In the present work, the photocatalytic activity of the ZC3G15 ternary nanocomposites show 99% and 93% of degradation efficiency respectively against RhB dye and 4-chlorophenol for 20 min under visible light irradiation. Thus, the simple solid-state method provides the effective ternary nanocomposites heterostructures light harvesting material for energy and environmental remediation.  相似文献   

5.
This study mainly focuses on the synthesis of two allotropes of graphene, graphene oxide (GO) and reduced graphene oxide (rGO), by the modified Hummers' method and chemical reduction method, respectively. Sm2O3/GO and Sm2O3/rGO nanocomposites were further synthesized in the presence of the cationic surfactant CTAB via the sol–gel method followed by the reflux method. Synthesized nanocomposites were subjected to characterization by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and UV–Visible spectroscopy to explore structural, thermal, optical, and photocatalytic properties. Characteristic FTIR peaks were observed in nanocomposites, and the bond length of the Sm-O bond was calculated. The Coats-Redfern method was employed to calculate the kinetics and thermodynamic parameters. Hexagonal crystallite shapes of Sm2O3/GO and Sm2O3/rGO nanocomposites with 11.8 and 13.13 nm crystallite sizes and 3.9 and 2.5 eV optical band gaps were observed. The photocatalytic efficiency of Sm2O3/GO and Sm2O3/rGO nanocomposites was assessed against the degradation of methylene blue in the presence of sunlight, and its degradation was confirmed through FTIR. The antimicrobial activities were also performed against the bacterial strains Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus.  相似文献   

6.
BiVO4-GO-PVDF (PVDF = Polyvinylidene Difluoride) photocatalyst is successfully synthesized by ultrasonication method and characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy techniques. Morphology of BiVO4-GO-PVDF looks like a human embryo embedded inside an amniotic sac. Photocatalytic performance of BiVO4-GO-PVDF for decolorization of methylene blue is investigated. BiVO4-GO-PVDF system reveals enhanced photocatalytic activity degradation of methylene blue (MB), Rhodamine B (RhB) & Safranin-O (SO) in water under visible light irradiation as compared to the pure BiVO4 catalyst, BiVO4 & PTFE decorated on the graphene sheet. The experimental result reveals that the covering of graphene sheets in this composite catalyst enhances photocatalytic performance under visible light. This enhanced activity is mainly attributed to effective quenching of the photogenerated electron-hole pairs confirmed by photoluminescence spectra. Trapping experiments of radicals and holes were conducted to detect reactive species generated in the photocatalytic system, experimental results revealed that direct hole oxidation reaction is obviously dominant during photocatalytic reactions on the BiVO4-GO-PVDF system.  相似文献   

7.
The enhancement of photocatalytic activity of TiO2 can be made either by promoting absorption efficiency of photon energy or by reducing recombination losses of photogenerated charge carriers, for which fabrication of nanocomposite structure with carbon materials is an optional selection. Among various nanocarbons, graphene (G), graphene oxide (GO), and reduced graphene oxide (rGO) are more favorable as the counterpart materials because they can provide availability of both obverse and reverse surface, thus doubling effective sites for adsorption, loading of nanoparticles, and interfacial interaction with the loaded nanoparticles. Composition of G/GO with titania, therefore, is a hopeful strategy for achieving synergy or cooperative effect in photocatalysis. In this personal account, we focus on the background and methodology of several soft chemical approaches that we have utilized up to date to fabricate nanocomposites of G/GO and titania, aiming to shed light on the importance of designing of nanocomposite structure for enhancing photocatalysis. In addition, we emphasize the role of interfacial interaction between carbon and titania by exemplifying a hybridized photocatalyst based on inexpensive biomass‐derived carbon sphere (CS), and demonstrate that it is a crucial influential factor underlying an enhanced visible light photocatalysis. CS can be a better selection as a counterpart component than G/GO, whose core‐shell composing structure with titania (TiO2@CS) can efficiently induce charge transfer so as to achieve a much higher photocatalytic performance under visible light illumination as compared to the composite of rGO and titania.  相似文献   

8.
Two-dimensional (2-D) BiVO4 nanosheets-graphene (GR) composites with different weight addition ratios of GR have been prepared via a facile wet chemistry process. X-ray diffraction (XRD), Raman spectra, X-ray photoelectron spectra (XPS), UV-vis diffuse reflectance spectra (DRS), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), nitrogen adsorption-desorption, transient photocurrent response and photoluminescence (PL) spectra were employed to determine the properties of the samples. It is found that BiVO4 nanosheets could pave well on the surface of graphene sheets. BiVO4 nanosheets-GR composites with a proper addition amount of GR exhibited higher photocatalytic activity than bare BiVO4 nanosheets toward liquid-phase degradation of rhodamine B (RhB) and methyl orange (MO) under visible light irradiation. The enhancement of photocatalytic activities of BiVO4 nanosheets-GR composites can be attributed to the effective separation of photoexcited electron-hole pairs. This work not only provides a simple strategy for fabricating specific 2-D semiconductor-2-D GR composites, but also opens a new window of such 2-D semiconductor-2-D GR composites as visible light photocatalysts toward an improved visible light photoactivity in purifying polluted water resources.  相似文献   

9.
采用一步水热法制备Bi2MoO6/BiVO4复合光催化剂. 利用X 射线衍射(XRD)、场发射扫描电子显微镜(FESEM)、高分辨透射电子显微镜(HRTEM)等手段对其晶体结构和微观结构进行了表征. 结果表明, Bi2MoO6纳米粒子沉积在BiVO4纳米片表面从而形成异质结结构. 紫外-可见漫反射光谱(UV-Vis DRS)表明所制备的Bi2MoO6/BiVO4异质结较纯相Bi2MoO6和BiVO4对可见光吸收更强. 由于形成异质结结构及其光吸收性能使Bi2MoO6/BiVO4 光催化活性有较大提高. 可见光下(λ>420 nm)光催化降解罗丹明B (RhB)实验结果表明,Bi2MoO6/BiVO4光催化活性较纯相Bi2MoO6和BiVO4高. Bi2MoO6/BiVO4样品光催化性能提高的原因是Bi2MoO6和BiVO4形成异质结, 从而有效抑制光生电子-空穴对的复合, 增大了可见光吸收范围及比表面积.  相似文献   

10.
In this work, we develop a novel environmentally friendly strategy toward one-pot synthesis of CuS nanoparticle-decorated reduced graphene oxide (CuS/rGO) nanocomposites with the use of l-cysteine, an amino acid, as a reducing agent, sulfur donor, and linker to anchor CuS nanoparticles onto the surface of rGO sheets. Upon visible light illumination (λ > 400 nm), the CuS/rGO nanocomposites show pronounced enhanced photocurrent response and improved photocatalytic activity in the degradation of methylene blue (MB) compared to pure CuS. This could be attributed to the efficient charge transport of rGO sheets and hence reduced recombination rate of excited carriers.  相似文献   

11.
Current work presents a facile, cost-effective, and green method to synthesize copper selenide nanostructures and copper selenide/graphene nanocomposites. The products were synthesized by a co-precipitation method by glycine amino acid as a green surfactant and graphene oxide (GO) sheets as a graphene source. X-ray diffraction patterns (XRD) of the products indicated that the products were Cu2Se3 with tetragonal phase. Fourier transform infrared (FTIR) spectroscopy and the XRD patterns indicated that the GO sheets were changed into reduced GO (rGO) during the synthesis process. Scanning and transmission electron microscopy (SEM and TEM) images showed the nanoparticles (NPs) that were decorated on rGO sheets had the significantly smaller size in compared to the pristine NPs. UV-vis results revealed that, the absorption peak of the products were in the visible region with a band-gap value between 1.85 eV and 1.95 eV. Finally, the products were applied as photocatalytic materials to remove Methylene Blue (MB) dye under solar-light and visible-light irradiation conditions. It was observed; the rGO had a significant role in enhancing the photocatalytic performance of the products and Cu2Se3/rGO (15%) could degrade more than 91% and 73% of MB only during 1 h under solar-light and visible-light sources, respectively.  相似文献   

12.
In this study, a novel ternary AgI/ZnIn2S4/BiVO4(AZB) composite photocatalyst was successfully prepared by hydrothermal method and in-situ precipitation method. The as-synthesized samples were characterized by XRD, SEM, TEM, XPS and so on, and the photocatalytic activity was evaluated through photocatalytic degradation of tetracycline (TC) under visible light irradiation. When the molar ratio of Bi to Ag was 1:1, the degradation rate of TC can reach 91.44 % within 150 min. The AZB heterojunction demonstrated outstanding efficiency with the apparent reaction rate constants of 0.02118 min?1 for TC removal, was 4.68, 3.27 and 3.27 times higher than that of pure BiVO4, AgI and ZnIn2S4. Based on active species trapping experiments and ESR analysis, a dual Z-Scheme pathways among BiVO4, AgI and ZnIn2S4 for effective separation of photogenerated charges was recommended. This work provided a promising insight for the design of ternary dual Z-scheme heterojunction with multilevel electron transfer to present greater photo-absorption, charge separation, and photodegradation for environmental decontamination.  相似文献   

13.
In this paper, ZnFe2O4, a visible light active photocatalyst, was comodified by graphene oxide (GO) and Ag nanoparticles (NPs) to form ZnFe2O4–Ag/rGO nanocomposite (NC) by facile one‐pot hydrothermal method. Reduction of GO and formation of ZnFe2O4 and Ag nanoparticles occurred simultaneously during hydrothermal reaction. The photocatalytic activity of the NC was investigated under visible light, for the degradation of 17α‐ethinylestradiol (EE2), a nondye compound, which also is an emerging pollutant with endocrine‐disrupting activity. The pseudo rate constant (k′) of as‐synthesized ZnFe2O4–Ag/rGO NC was higher by the factor of 14.6 and 5.6 times than the corresponding ZnFe2O4 and ZnFe2O4/rGO respectively. The synergistic interactions between ZnFe2O4, Ag and rGO leading to decreased aggregation of the NPs, increased surface area, better absorption in visible region, effective electron–hole generation transfer. However, in the presence of humic acid (HA), the photosensitization effect was predominated by competitive interaction resulting in only 80% removal of EE2 within the same time. Moreover, the composite can easily be magnetically separated for reuse.  相似文献   

14.
In this article, novel Ag–ZnO/g-C3N4/GO ternary nanocomposites were prepared via co-precipitation method by 1%w Ag, 50% w g-C3N4, 10% w GO concentration and applied in dynamic membranes. The characteristics of Ag–ZnO/g-C3N4/GO nanocomposite were evaluated by various techniques such as X-ray diffraction, field emission scanning electron microscopy, energy dispersive X-ray map, transmission electron microscopy, X-ray photoelectron spectroscopy, photocatalyst. The photocatalytic degradation of methylene blue was investigated under visible light. The photocatalytic efficiency of 93.43% for methylene blue degradation was obtained for Ag–ZnO/g-C3N4/GO nanocomposite after 50 min of irradiation, which was remarkably higher than that of pure ZnO, bare g-C3N4, Ag–ZnO, and Ag–ZnO/g-C3N4 at the same irradiation time. Likewise, in self-forming and pre-coated membranes, ternary nanocomposites can play a vital role in the membrane surface properties, as well as their decolorization performance. The rejection of methylene blue was 30% in pure polyethersulfone membrane, while the photocatalytic degradation of methylene blue in Ag–ZnO/g-C3N4/GO nanocomposites was 88.46% and 98.86% after 10 and 15 min of irradiation in both self-forming and pre-coated dynamic membranes, respectively. Experimental results show that the dynamic membrane possesses a higher ability for degradation of MB in a shorter period of time than the static system.  相似文献   

15.
Co-doped BiVO4, a visible-light-responsive photocatalytic semiconductor, was synthesized using a microwave hydrothermal method. The doped sample exhibited much higher photocatalytic activity for malachite green degradation under visible light irradiation than undoped BiVO4. Similarly, improved inactivation efficiency toward Escherichia coli and Chlamydomonas pulsatilla (green tide) were observed with Co-doped BiVO4. The degradation of malachite green by Co-doped BiVO4 reaches 99% within 90 min irradiation to visible light. Similarly, the inactivation of Escherichia coli reaches 81.3% in 5 h and Chlamydomonas pulsatilla reaches 65.6% in 1 h irradiation to visible light. The enhanced photoactivity is believed to be due to the increment of the visible light absorption range by narrowing the band gap energy. In addition, the highly exposed reactive (010) facets can efficiently capture the photoinduced electrons, promote charge separation, and reduce recombination probability. Thus, these findings provide mechanistic insight into the effectiveness of Co-doped BiVO4 semiconductors for the treatment of wastewater that contains industrial effluents and microorganisms.  相似文献   

16.
Construction of an effective heterojunction for unimpeded flow of photogenerated charges and their prolonged separation is imperative for environmental photocatalysis. Herein, we have designed an efficient magnetic ZnO/BiVO4 type-II heterostructure, which was employed for proficient degradation of persistent methyl violet dye with an efficiency of 97.6% in 90 min and a hazardous organic pollutant, namely, bisphenol A. UV-DRS and photoluminescence studies demonstrated that the fabricated nanocomposite exhibited effective light absorption and prolonged charge separation, thereby resulting in high photocatalytic efficacy under visible light irradiation. The efficacy of developed magnetic ZnO/BiVO4 was also compared with pristine BiVO4 and undoped magnetic ZnO, which indicated that the constructed heterostructure displayed approximately threefold and sixfold activity in contrast with bare BiVO4 and undoped magnetic ZnO nanoparticles, respectively. Radical trapping studies, ESR analysis along with GC-MS analysis were conducted to elucidate the mechanistic pathway during the photodegradation process. This work provides a rational technical approach and research ideas for photocatalytic degradation of harmful organic pollutants in an environment-friendly manner by employing energy-efficient LEDs. Besides, good recyclability of catalyst makes it a promising candidate for large-scale applications.  相似文献   

17.
FeMoO4 nanorods and their rare earth (Eu3+ and Tb3+) doped composites with nitrogen doped graphene (NG) were synthesized by facile hydrothermal method in aqueous medium. X-ray diffraction (XRD) analysis of the as-synthesized samples was done to study the phase purity and crystalline nature. FTIR and Raman Spectroscopy have been studied for investigating the bonding in nanostructures. The surface morphology of the samples was investigated with field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The photolumniscent nature of the samples was investigated by the using the fluorescence spectrophotometer. The photocatalytic degradation efficiency of the prepared pure FeMoO4 and its rare earth doped composites with nitrogen doped graphene was evaluated as function of visible light irradiation versus concentration of methylene blue (MB dye). The prepared nanocomposites show enhanced photocatalytic efficiency as compared to the bare FeMoO4 nanorods.  相似文献   

18.
经由溶剂热反应、光辅助还原过程制备Bi/Bi VO_4Bi_4V_2O_(11)纳米复合光催化材料。通过X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、高分辨率透射电子显微镜(HRTEM)、X射线光电子能谱(XPS)、紫外-可见漫反射光谱(UV-Vis DRS)、N_2吸附-脱附等温线和光致发光(PL)等手段对该复合物进行表征。实验结果表明当金属Bi与BiVO_4Bi_4V_2O_(11)的质量比值为0.8,可见光照射30 min时,Bi/BiVO_4Bi_4V_2O_(11)复合催化剂对罗丹明B(RhB)的降解率可达95.6%。此外,Bi/BiVO_4Bi_4V_2O_(11)对四环素(TC)的降解也表现出增强的光催化性能。Bi/BiVO_4Bi_4V_2O_(11)复合材料提升的光催化性能可能归因于金属Bi的表面等离子体共振(SPR)效应、拓宽的可见光吸收范围和增大的比表面积。此外,提出了复合光催化剂可能的光催化机理。  相似文献   

19.
A new idea of prepared method for BiVO4 nano-powders hydrothermal synthesis process was developed to avert the existent shortcomings of hydrothermal method. The thermal stability, phase structure, light absorption property, and morphology of the catalyst prepared were characterized by thermogravimetric analyzer (TG), X-ray diffraction (XRD), ultraviolet visible spectrophotometer (UV/Vis), and transmission electron microscopy (TEM), respectively. Using methyl orange (MO) as the target degradation material and a 500-W dysprosium lamp as the visible light source to investigate photocatalytic performance of BiVO4. We successfully prepared BiVO4 powders with small particle size, less agglomeration and uniform distribution by carbon adsorption hydrothermal method, and the absorption wavelength of light was red-shifted, these all rendered the absorption capacity of visible light region enhancing with 94 % high photocatalytic degradation rate of methyl orange at 60 min. And the possible mechanism was also discussed in this study.  相似文献   

20.
This study shows a facile approach for the preparation of CeO2 nanoparticles decorated with porous nitrogen‐doped graphene (NG) nanosheets for effective photocatalytic degradation of methylene blue (MB). NG nanosheets were first synthesized using a hydrothermal method and then nitrogen‐doped graphene‐cerium oxide (NG‐CeO2) was prepared through mixing of cerium nitrate with different concentrations of NG under ultrasonication followed by hydrothermal treatment. The synthesized nanocomposites were characterized using X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and field emission scanning electron microscopy (FE‐SEM). The photocatalytic activity of the synthesized nanocomposites was analyzed against MB dye. Results showed that the nanocomposites of NG‐CeO2 have an average particle size of 20 nm. The as‐prepared NG‐CeO2 nanocomposites exhibited outstanding photocatalytic activity for dye degradation under visible light irradiation, which could be attributed to synergistic effects between the NG nanosheets and CeO2. The quantum of photodegradation increases with the increase of the NG content in the nanocomposites.  相似文献   

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