Visible-light-induced photocatalytic performances of ZnO-CuO nanocomposites for degradation of 2,4-dichlorophenol

Nanostructured ZnO and CuO, and coupled oxides, i.e., ZnCu, Zn2Cu, and ZnCu2, with ZnO:CuO molar ratios of 1:1, 2:1, and 1:2, respectively, were successfully prepared through a simple, one-step, mi-crowave-assisted urea–nitrate combustion synthesis, without the use of organic solvents or surfac-tants. The prepared samples were characterized using X-ray diffraction, X-ray photoelectron spec-troscopy, scanning electron microscopy, energy-dispersive X-ray analysis, transmission electron microscopy, Fourier-transform infrared spectroscopy, diffuse reflectance spectroscopy, and photo-luminescence spectroscopy. The optical absorption of ZnO extended into the visible region after CuO loading. The photocatalytic activities of ZnO, CuO, and the coupled oxides were evaluated based on photodegradation of 2,4-dichlorophenol under visible-light irradiation. The coupled metal oxide Zn2Cu showed the best photocatalytic activity;this was mainly attributed to the extended photore-sponsive range and the increased charge separation rate in the nanocomposite. The photocatalytic degradation process obeyed pseudo-first-order kinetics. The results suggest that the coupled metal oxide Zn2Cu has potential applications as an efficient catalytic material with high efficiency and recyclability for the photocatalytic degradation of organic pollutants in aqueous solution under visible-light irradiation.     

可见光下具有高光子效应和光催化活性的CuS-石墨烯氧化物/TiO2复合材料的制备（英文）

CuS-graphene oxide/TiO2 composites were prepared using a sol-gel method to improve the photocatalytic performance of the photocatalyst. The composites were characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray analysis, and transmission electron microscopy. The photocatalytic activities were examined by the degradation of methylene blue (MB) under visible-light irradiation. The photodegradation of MB under visible-light irradiation reached 90.1% after 120 min. The kinetics of MB degradation was plotted alongside the values calculated from the Langmuir-Hinshelwood equation. The CuS-graphene oxide/TiO2 sample prepared using 0.2 mol of TiO2 showed the best photocatalytic activity. This was attributed to a cooperative reaction as a result of increased photoabsorption by graphene oxide and an increased photocatalytic effect by CuS.     

Preparation,characterization and photocatalytic properties of BiOBr/ZnO composites

BiOBr/ZnO composite photocatalysts were prepared by a simple hydrothermal method. The as-prepared samples were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM), high-resolution transmission electron microscopy(HRTEM), UV–Vis diffusion reflectance spectroscopy(DRS) and photoluminescence(PL) spectroscopy, respectively. The photocatalytic activities were evaluated by the degradation of methyl blue(MB) under the simulated sunlight irradiation. Among all the samples, the BiOBr/ZnO composite with a mole ratio of 3:1(Bi:Zn) exhibited the best photocatalytic activity. The improvement of photocatalytic activity was mainly attributed to the low recombination ratio of photo-induced electron-hole pairs. The possible photocatalytic mechanism was discussed on the basis of the band structures of BiOBr and ZnO.     

Preparation, characterization of Mo, Ag-loaded BiVO4 and comparison of their degradation of methylene blue

Two types of metal-loaded visible-light-driven photocatalysts,Mo-BiVO4and Ag-BiVO4,were synthesized by wet impregnation method.Material poperties were characterized by UV-vis diffuse reflectance spectroscopy,X-ray diffraction,field emission scanning electron microscopy,X-ray photoelectron spectroscopy and low temperature nitrogen adsorption-desorption.Photocatalytic activity of the obtained materials was investigated through degrading methylene blue(MB) solution under visible-light irradiation.The results reveal that both metal loaded-BiVO4catalysts have monoclinic scheelite structure.Mo and Ag exist as oxides on the surface of the particles.The changes of absorption in visible-light region,band gap(E g) and specific surface area(A BET) caused by loading Ag are more obvious than those caused by loading Mo.But the isoelectric point of Ag-BiVO4decreases less than that of Mo-BiVO4does.Both catalysts show higher photocatalytic activity than pure BiVO4,resulting in the significantly improved efficiency of degradation of MB.And the degradation efficiency of these two metal-loaded BiVO4photocatalysts is similar to each other.However,mechanisms of such enhancement are different.The decrease of isoelectric point helps Mo-BiVO4improve the degradation efficiency.As for Ag-BiVO4,the augmentation of absorption in visible-light region as well as the abatement of E g plays more important roles.     

Sunlight responsive photocatalysts: AgBr/ZnO hybrid nanomaterial

A novel high-effective sunlight-induced AgBr/ZnO hybrid nanophotocatalyst has been synthesized and it was characterized by different techniques such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and ultraviolet-visible spectrophotometry (UV-vis). The AgBr/ZnO hybrid nanophotocatalyst has excellent photocatalytic activity for photodegradation of methyl orange (MO) under sunlight irradiation. The MO degradation efficiency for AgBr/ZnO is about 98% after 1 hour under sunlight irradiation. These results suggested that AgBr/ZnO is a promising candidate for the development of highly efficient sunlight photocatalysts. In addition, the photocatalytic mechanism of AgBr/ZnO under sunlight irradiation is illustrated and discussed.     

Hydrothermal Synthesis of CdIn2S4 and Photocatalytic Degradation of Methyl Orange under Visible-light Irradiation

CdIn2S4 microspheres were synthesized by a facile hydrothermal method with the temperature ranging from 120 to 200 ℃. X-ray diffraction, UV-vis diffuse reflectance spectroscopy, nitrogen sorption analysis, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy were used to characterize the products. It was found that the crystallographic structure and optical property of the products synthesized at different temperature were almost the same. The SBET of CdIn2S4 products decreased when the synthesized temperature increased, and the largest SBET was 33.16m2g-1 (120 ℃ sample). The degradation of methyl orange (MO) under the visible-light irradiation had been used as a probe reaction to investigate the photocatalytic activity of the as-prepared CdIn2S4, which showed that the CdIn2S4 sample synthesized at 120 ℃ presented the best photocatalytic activity for MO degradation.     

Preparation and characterization of In and Cu co-doped ZnS photocatalysts for hydrogen production under visible light irradiation

In this work, a new photocatalyts In(0.1),Cu(x)-Zn S(x = 0.01, 0.03, 0.05) is successfully synthesized using simple hydrothermal method. The physical and chemical properties of the In and Cu co-doped Zn S photocatalyst were characterized by X-ray diffraction(XRD), field emission scanning electron microscopy(FESEM), diffuse reflectance UV-visible spectroscopy(DR UV-visible) and photoluminescence spectroscopy(PL). The photocatalytic activity of the as-prepared In and Cu co-doped Zn S for hydrogen production from water with Na_2SO_3 and Na_2S as sacrificial agent under visible light irradiation(λ≥ 425 nm) was investigated. The presence of co-dopants facilitated the separation of electron-hole as well as increases the visible light absorption. The absorption edge of the co-doped Zn S photocatalyst shifted to longer wavelength as the amount of Cu increases. This indicates that the absorption properties depended on the amount of Cu doped. The photocatalytic activity of single doped In(0.1)-Zn S was significantly enhanced by co-doping with Cu under visible light irradiation. The highest photocatalytic activity was observed on In(0.1),Cu(0.03)-Zn S with the hydrogen production rate of 131.32 μmol/h under visible light irradiation.This is almost 8 times higher than single doped In(0.1)-Zn S.     

Preparation, characterization and photocatalytic performance of Mo-doped ZnO photocatalysts

A series of Mo-doped ZnO photocatalysts with different Mo-dopant concentrations have been prepared by a grinding-calcination method.The structure of these photocatalysts was characterized by a variety of methods,including N 2 physical adsorption,X-ray diffraction(XRD),scanning electron microscopy(SEM),Fourier transform infrared(FT-IR) spectroscopy,photoluminescence(PL) emission spectroscopy,and UV-vis diffuse reflectance spectroscopy(DRS).It was found that Mo 6+ could enter into the crystal lattice of ZnO due to the radius of Mo 6+(0.065 nm) being smaller than that of Zn 2+(0.083 nm).XRD results indicated that Mo 6+ suppressed the growth of ZnO crystals.The FT-IR spectroscopy results showed that the ZnO with 2 wt.% Mo-doping has a higher level of surface hydroxyl groups than pure ZnO.PL spectroscopy indicated that ZnO with 2 wt.% Mo-doping also exhibited the largest reduction in the intensity of the emission peak at 390 nm caused by the recombination of photogenerated hole-electron pairs.The activities of the Mo-doped ZnO photocatalysts were investigated in the photocatalytic degradation of acid orange II under UV light(λ = 365 nm) irradiation.It was found that ZnO with 2 wt.% Mo-doping showed much higher photocatalytic activity and stability than pure ZnO.The high photocatalytic performance of the Mo-doped ZnO can be attributed to a great improvement in the surface properties of ZnO,higher crystallinity and lower recombination rate of photogenerated hole-electron(e-/h+) pairs.Moreover,the undoped Mo species may exist in the form of MoO3 and form MoO3 /ZnO heterojunctions which further favors the separation of e-/h+ pairs.     

Effects of Ag Doping Content and Dispersion on the Photocatalytic and Antibacterial Properties in ZnO Nanoparticles

ZnO nanoparticles(NPs)with different contents of Ag dopants were obtained by one-step solvothermal method.The crystalline structures of the prepared composites were characterized by means of X-ray diffraction(XRD).The morphology and composition of the samples were studied by means of scanning transmission electron microscopy(TEM)5 X-ray photoelectron spectroscopy(XPS)and electron microscopy(SEM).Photoluminescence(PL)spectra have been used to investigate pure ZnO,Ag-ZnO and Ag-ZnO-PVP NPs to determine the effect of composition on PL properties.It was found that the Ag-ZnO samples showed stronger emissions than pure ZnO.The catalytic activity of samples was measured by the degradation rate of R6G,which exhibited that Ag-ZnO nanocomposite demonstrated enhanced photocatalytic activity compared to the pure ZnO NPs.The possible influence factors to the photocatalytic and antibacterial activities of the sample were explored,including Ag contents and dispersion.It was presented that the photocatalytic activity of Ag-ZnO-PVP was better than that of Ag-ZnO and it showed the highest photocatalytic activity with 7%of Ag content.The Ag-ZnO-PVP can kill the Escherichia coli(E.coli)cells.     

氧化铈纳米粒子光催化降解亚甲基蓝的动力学和机理

 CeO2 nanocrystals were synthesized by a simple precipitation method and calcination at 600 °C. (NH4)2Ce(NO3)6 and ammonia were used as precursors. The CeO2 nanoparticles were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, and N2 adsorption. The photodegradation of methylene blue catalyzed by CeO2 nanoparticles was studied under UV and sunlight irradiation. The highest degradation was obtained with 1.0 g/L CeO2 at pH 11 within 125 min. The pseudo first order rate constants of dye bleaching were calculated as 16.2x10-3 and 15.7x10-3 min-1 under UV and sunlight irradiation, respectively. The effect of iso-PrOH, iodide ion, and H2O2 was studied to predict the pathway of dye degradation. The obtained results indicate the effect of photogenerated holes in the degradation mechanism of the dye. Also, the photocatalytic activity of the prepared photocatalyst was studied in the presence of several negative ions.     

Synthesis and Photocatalytic Properties of Coupled Nanocrystalline ZnO/ZnS in Nafion Membrane

The coupled nanocrystalline ZnO/ZnS was fabricated and immobilized in Nafion membrane by using sodium sulfide (Na2S) as the single anion precursor. The molar ratio of ZnO to ZnS can be controlled by simply adjusting the reaction time. The as-prepared ZnO/ZnS-Nafion samples were characterized by various methods, including optical absorption, X-ray diffraction and high-resolution transmission electron microscopy. These coupled ZnO/ZnS nanocrystals embedded in Nafion membrane displayed excellent photocatalytic activities for their efficient charge separation properties. A mechanism of ZnO/ZnS nanoparticle fabrication in Nafion was deduced from the solubility difference, and the photocatalytic mechanism of coupled ZnO/ZnS was discussed as well.     

Magnetically recoverable Cu2O/Fe3O4 composite photocatalysts：Fabrication and photocatalytic activity

A magnetically separable Cu2O/Fe3O4 magnetic composite photocatalyst was synthesized in large quantities by a fast and simple route. The as-prepared photocatalysts were characterized by scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, X-ray photoelectron spectroscopy （XPS） and X-ray diffraction （XRD）. Furthermore, the Cu2O/Fe3O4 composite photocatalysts were tested using methyl orange （MO） degradation reaction under visible light irradiation （100 mW/cm2） and demonstrated to have a high photocatalytic efficiency toward the decomposition of MO under visible light irradiation with good recyclability.     

Citric acid-assisted synthesis of nano-Ag/BiO Br with enhanced photocatalytic activity

In this study, silver nano-particles have been anchored in the surface of Bi OBr photocatalysts by a citric acid-assisted photoreduction method. The citric acid was served as a chelating and reductive agent for the preparation of Ag-decorated Bi OBr photocatalysts(named as Ag/Bi OBr-2). The as-synthesized samples were characterized by X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS), scanning electron microscopy(SEM), transmission electron microscopy(TEM), and UV-Vis diffuse reflection spectroscopy(DRS). The Ag/Bi OBr-2 photocatalyst exhibited excellent and stable photocatalytic activities on MO and phenol degradation under simulated sunlight irradiation. The enhanced photocatalytic activity could be ascribed to the smaller size, rough surface, and the surface plasma resonance(SPR) effect of Ag. Also, the Schottky junction, between the surface of the Bi OBr and silver nanoparticles, accelerated the efficient transfer and separation of photoinduced electron-hole pairs and promoted the photocatalytic performance. The active species tests indicated that the superoxide radical(·O-2) was responsible for the enhanced photocatalytic performance of Ag/Bi OBr-2. Finally, a possible photocatalytic mechanism was proposed.     

A general synthesis of transition metal oxides with assistance of organic amines and their electrocatalytic properties

Several transition metal oxides,including α-Fe2O3,Fe3O4,Co3O4,NiO,CuO and ZnO,were synthesized via an easily controlled hydrothermal method at assistance of organic amine(cyclohexylamine or triethylamine).The synthesized samples were identified and characterized by X-ray diffraction(XRD),Transmission Electron Microscopy(TEM),High-resolution Electron Microscopy(HR-TEM),Field Emission Scanning Electron Microscopy(FE-SEM),N2 adsorption/desorption measurement.The resultant metal oxides displayed various morphol...     

ZnO nanopowders and their excellent solar light/UV photocatalytic activity on degradation of dye in wastewater

Low-cost and scalable preparation,high photocatalytic activity,and convenient recycle of Zn O nanopowders(NPs)would determine their practical application in purifying wastewater.In this contribution,ZnO NPs were scalably synthesized via the simple reaction of Zn powder with H_2O vapor in autoclave.The structural,morphological and optical properties of the samples were systematically characterized by X-ray diffraction,scanning electron microscopy,Fourier transform infrared spectra,transmission electron microscopy,Micro-Raman,photoluminescence,and ultraviolet-visible spectroscopy.The as-prepared Zn O NPs are composed of nanoparticles with 100–150 nm in diameter,and have a small Brunauer-Emmett-Teller surface area of 6.85 m~2/g.The formation of Zn O nanoparticles is relative to the peeling of H_2 release.Furthermore,the product has big strain-stress leading to the red-shift in the band gap of product,and shows a strong green emission centered at 515 nm revealing enough atomic defects in Zn O NPs.As a comparison with P25,the obtained dust gray Zn O NPs have a strong absorbance in the region of 200–700 nm,suggesting the wide wave-band utilization in sunlight.Based on the traits above,the Zn O NPs show excellent photocatalytic activity on the degradation of rhodamine B(Rh-B)under solar light irradiation,close to that under UV irradiation.Importantly,the Zn O NPs could be well recycled in water due to the quick sedimentation in themselves in solution.The low-cost and scalable preparation,high photocatalytic activity,and convenient recycle of Zn O NPs endow themselves with promising application in purifying wastewater.     

Study on the Different Photocatalytic Performances for Tetracycline Hydrochloride Degradation of p-block Metal Composite Oxides Sr1.36Sb2O_6 and Sr2Sb2O_7

p-block metal composite oxides Sr_1.36Sb₂O₆ and Sr₂Sb₂O₇ synthesized by a hydrothermal method as photocatalysts in the degradation of tetracycline hydrochloride under UV light irradiation have been extensively studied.The effects of synthesis conditions on the photocatalytic activity were discussed.The Sr_1.36Sb₂O₆-100°C-24 h-5 and Sr₂Sb₂O₇-150℃-24 h^-2 samples prepared under optimal conditions exhibited remarkably different photocatalytic activities.The essential factors influencing the difference of photocatalytic performance were revealed.The results showed that the different photocatalytic activities observed for Sr_1.36Sb₂O₆and Sr₂Sb₂O₇ could be attributed to their different electronic and crystal structures.Our work will provide a new perspective for the screening and design of p-block metal composite oxide photocatalysts to enhance the removal of organic pollutants in the environment.     

还原氧化石墨烯-硒化银纳米复合材料的水热合成与表征及其活性氧物种产生(英文)

A visible-light photocatalyst containing Ag2Se and reduced graphene oxide(RGO) was synthesized by a facile sonochemical-assisted hydrothermal method. X-ray diffraction, scanning electron mi-croscopy with energy-dispersive X-ray analysis, and ultraviolet-visible diffuse reflectance spectros-copy results indicated that the RGO-Ag2Se nanocomposite contained small crystalline Ag2Se nano-particles dispersed over graphene nanosheets and absorbed visible light. The high crystallinity of the nanoparticles increased photocatalytic activity by facilitating charge transport. N2 adsorp-tion-desorption measurements revealed that the RGO-Ag2Se nanocomposite contained numerous pores with an average diameter of 9 nm, which should allow reactant molecules to readily access the Ag2Se nanoparticles. The RGO-Ag2Se nanocomposite exhibited higher photocatalytic activity than bulk Ag2Se nanoparticles to degrade organic pollutant rhodamine B and industrial dye Texbrite BA-L under visible-light irradiation(λ 420 nm). The generation of reactive oxygen spe-cies in RGO-Ag2Se was evaluated through its ability to oxidize 1,5-diphenylcarbazide to 1,5-diphenylcarbazone. The small size of the Ag2Se nanoparticles in RGO-Ag2Se was related to the use of ultrasonication during their formation, revealing that this approach is attractive to form po-rous RGO-Ag2Se materials with high photocatalytic activity under visible light.     

Preparation of ZnO/GO composite material with highly photocatalytic performance via an improved two-step method

ZnO/graphene oxide(ZnO/GO) composite material,in which ZnO nanoparticles were densely coated on the GO nanosheets,was successfully prepared by an improved two-step method and characterized by IR, XRD,TEM,and UV-vis techniques.The improved photocatalytic property of the ZnO/GO composite material,evaluated by the photocatalytic degradation of methyl orange(MO) under UV irradiation,is ascribed to the intimate contact between ZnO and GO,the enhanced adsorption of MO,the quick electron transfer from excited ZnO particles to GO sheets and the activation of MO molecules viaπ-πinteraction between MO and GO.     

纳米 Ce1MgxZr1-xO2 固体多相催化剂的制备、表征及催化合成四氢苯并[b]吡喃衍生物的性能

 A series of Ce1MgxZr1-xO2 mixed metal oxides with different molar ratios were prepared by simple co-precipitation and were characterized by X-ray diffraction, infrared spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, temperature-pro- grammed desorption of CO2, and N2 adsorption techniques. The prepared materials were tested for catalytic activity by the synthesis of tet-rahydrobenzo[b]pyran derivatives using a three component reaction (aromatic aldehydes, malononitrile, and dimedone) in an ethanol me-dium. The best catalytic activity was obtained with Ce1Mg0.6Zr0.4O2. The particle size or crystallite size was estimated using the De-bye-Scherrer equation. The addition of magnesium oxide into the ceria-zirconia lattice resulted in the formation of nanosized particles rang-ing from 5.41 to 9.78 nm. This work describes the catalytic behavior of magnesium oxide in mixed metal oxide systems.     

Preparation of TiO2/ITO film electrode by AP-MOCVD for photoelectrocatalytic application

Titanium dioxide (TiO2 ) thin films were grown onto Indium tin oxide (ITO) glass under atmospheric pressure by chemical vapor deposition (AP-MOCVD) using titanium tetraisopropoxide astitanium precursor. The as-prepared TiO2 /ITO films were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and photoelectrochemical measurements. Their photocatalytic (PC) and photoelectrocatalytic (PEC) activities were evaluated based on the results of methyl orange dye (MO) degradation experiments in aqueous solution. The difference between the front side (EE, electrolyte/electrode interface) and the back side (SE, substrate/electrode interface) illumination was evaluated in both photocurrent and MO degradation experiments. The effect of the film thickness on degradation rate by PEC under the two illumination directions was also studied. Stability of TiO2 /ITO film electrode was investigated in repetitive degradation experiments. Overall, the TiO2 /ITO film with thickness ranging from 321 to1440 nm deposited by MOCVD method is an effective photoelectrode for MO degradation under SE illumination in PEC reaction system.