Preparation and photocatalytic performance of porous ZnO microrods loaded with Ag

Porous silver-modified ZnO microrods photocatalysts were synthesized through direct thermal decomposition of the Ag-doped zinctartrate precursor,which was prepared by homogeneous precipitation method at 80 °C for 2 h.The obtained samples were characterized by XRD,FTIR,TG？DTA and UV-VIS absorption spectroscopy.The photocatalytic activity of the as-prepared porous Ag/ZnO microrods was tested with the photocatalytic degradation of methyl orange.The results indicate that doping Ag greatly improves the photocatalytic efficiency of ZnO and 3% Ag-doped（mole fraction） ZnO porous microrod photocatalyst exhibits the highest photocatalytic decolorization efficiency,leading to as much as 80% reduction of MO concentration in 120 min.Moreover,the 3% Ag-doped porous microrods also possess higher photocatalytic activity under the real sunlight irradiation.

Effects of Elemental Chemical State in NiFe2O4@TiO2 on the Photocatalytic Performance

The elemental chemical state of NiFe2O4@TiO2 was changed by the reduction in order to investigate its effects on the photocatalytic performance.The synthesized NiFe2O4@TiO2 samples were characterized by means of X-ray diffraction (XRD),high-resolution transmission electron microscopy (HRTEM),Fourier-transform infrared spectroscopy (FT-IR),X-ray photoelectron spectroscopy (XPS),magnetic and photocatalytic measurements.Unexpectedly,the reduction reaction does not produce oxygen vacancies Ov and TiOx in the TiO2 lattice.The optimal catalyst was obtained at the reducing temperature of 800℃,and its degradation efficiency De to the methylene blue and reaction rate constant Kapp are the highest,reaching 99.9% and 3×10^-2 min-1,respectively.The reason could not be explained by both the visible light absorption and the appropriate amount of Ov and TiOx.Instead,the lowest ratios of TiOH and Ti-O-Fe(Ni) may be responsible for the optimum photocatalytic performance.

Nanoparticle/Microsphere TiO_(2)/Bi_(2)WO_(6) Z-scheme Heterojunction with Excellent Visiblelight Photocatalytic Performance

Flower-like BiOBr/Bi_(2)WO_(6) Z-scheme heterojunction was prepared by a twostep solvothermal method.BiOBr microspheres were firstly synthesized through solvothermal method.Then the out part of the BiOBr microspheres was designed to react with Na2WO4 forming Bi_(2)WO_(6) nanosheets through ion exchange process.The BiOBr/Bi_(2)WO_(6) heterojunction has a larger BET surface area,smaller energy band gap,faster transfer of charge carriers and a much better visible-light photocatalytic performance than that of BiOBr and Bi_(2)WO_(6).It also has a better cycling stability than that of the BiOBr.Possible photocatalytic mechanism of the BiOBr/Bi_(2)WO_(6) heterojunction is proposed.

Preparation and photocatalytic performance of ZnO/ZnGa_2O_4 composite microspheres

ZnO/ZnGa_2O_4 composite microspheres with heterojunction were successfully synthesized by one-pot hydrothermal method.These samples were characterized by TG/DTA,XRD,TEM,HRTEM,UV-vis DRS,FL and BET techniques.The results indicated the as-prepared samples showed better degree of crystalline and large specific surface area.The photocatalytic activity was evaluated by degradation of methyl orange with the concentration of 50 mg/L under the irradiation of simulated sunlight.The effects of molar ratio of Zn to Ga and calcination temperature on the photocatalytic activity were investigated in detail.The results showed that the highest photocatalytic degradation efficiency was observed at the molar ratio of Zn to Ga of 1:0.5 in the starting materials and the calcination temperature of 400 °C.The maximum photocatalytic degradation rate of MO was 97.1% within 60 min under the simulated sunlight irradiation,which is greatly higher than that of ZnO and ZnGa_2O_4.

Synthesis of a Novel TiO_(2)@Ag_(3)PO_(4)Core-Shell Structure with Enhanced Photocatalytic Performance

Ag_(3)PO_(4)exhibits a high photocatalytic activity if exposed to visible light,however,it displays bottlenecks such as poor cycle-stability and mediocre ability to degrade methyl orange(MO)because of limited adsorption of MO molecules onto its surface.In this study,nano TiO_(2)prepared by a one-step method was combined with Ag_(3)PO_(4)to form a TiO_(2)@Ag_(3)PO_(4)heterojunction in order to improve this material both in terms of photocatalysis and photostability.After adding a KH-570 silane coupling agent,the photocatalytic performance of TiO_(2)@Ag_(3)PO_(4)could be improved even further,with the degradation rate of MO maintained at more than 90%after three cycles of visible in light.

Regulating the crystal phase of bismuth-based semiconductors for promoted photocatalytic performance

Numerous bismuth-based semiconductors(BBSs)with sophisticated and desirable structures used as photocatalysts for efficient photocatalytic degradation of water organic contaminants have attracted considerable attention.However,regulating the crystal phases and phase transition of BBSs for promoted photocatalytic performance is ignored.Herein,the unique crystal structure and band structure features of each typical BBSs,and the vital roles on phase controlling of each phase were systematically presented based on the classification of BBSs.Notably,the critical factors for the phase transition of BBSs and intrinsic driving forces endowed by phases of BBSs for enhanced photocatalytic performance of organic contaminants removal were also elucidated.This review will provide systematical guidelines and horizons for regulating the crystal phase and phase transition of BBSs,promoting photocatalytic degradation and mineralization of organic contaminants.

Enhanced Photocatalytic Performance of Surface-Modified TiO_(2) Nanofibers with Rhodizonic Acid

The improvement of the photocatalytic performance of TiO_(2) nanofibers(NFs),prepared by electrospinning,is achieved by surface modification with the rhodizonic acid(RhA).The condensation reaction between hydroxyl groups from TiO_(2) NFs and RhA is accompanied by the red-shift of optical absorption due to interfacial charge transfer(ICT)complex formation.Crystal structure,morphology,and optical properties of unmodified and surface-modified TiO_(2) NFs were analyzed.The photocatalytic performance of prepared samples has been examined through degradation of organic dye methylene blue.Superior photocatalytic activity of surface-modified TiO_(2) NFs with RhA is attributed to their enhanced optical properties,i.e.,the ability to harvest the photon energy in the visible spectral range.

Enhanced photocatalytic performance of SrTiO_(3) powder induced by europium dopants

In this work,Eu^(3+)doped SrTiO_(3)powders were synthesized by sol-gel method and the influences of Eu^(3+)dopants on the crystalline structure,micro structure mo rphology,electronic band-gap and photocatalytic performance for degradation of o rganic pollutant were investigated in detail.Research results reveal that the incorporated Eu^(3+)ions in SrTiO_(3)lattice are preferable to substitute the Sr^(2+)-Ti^(4+)ions pair by two Eu^(3+)ions.The presence of Eu^(3+)ions plays a significant role for the microstructure morphology of the S rTiO_(3)powders,leading to the formation of smaller size nanoparticles with a higher specific surface area.The light absorption capability of the resulting materials is improved owing to the narrowing of the band-gap induced by Eu^(3+)dopants.As a result,the enhanced photocatalytic activity application for photodegradation of Rhodamine B solution is demonstrated for the SrTiO_(3)powders doped with Eu^(3+)ions.

Excellent photocatalytic performance under visible-light irradiation of ZnS/rGO nanocomposites synthesized by a green method

ZnS/graphene nanocomposites with different graphene concentrations （5, 10 and 15 wt.%） were synthesized using L-cysteine as surfactant and graphene oxide （GO） powders as graphene source. Excellent performance for nanocomposites to remove methylene blue （MB） dye and hexavalent chromium （Cr（VI）） under visible-light illumina- tion was revealed. TEM images showed that ZnS NPs were decorated on GO sheets and the GO caused a significant decrease in the ZnS diameter size. XRD patterns, XPS and FTIR spectroscopy results indicated that GO sheets changed into reduced graphene oxide （rGO） during the synthesis process. Photocurrent measurements under a visible- light source indicated a good chemical reaction between ZnS NPs and rGO sheets.

Solvothermal fabrication of Bi_(2)MoO_(6) nanocrystals with tunable oxygen vacancies and excellent photocatalytic oxidation performance in quinoline production and antibiotics degradation

Novel Bi_(2)MoO_(6) nanocrystals with tunable oxygen vacancies have been developed via a facile low-cost approach with the assistance of a glyoxal reductant under solvothermal conditions.With the introduction of oxygen vacancies,the optical absorption of Bi_(2)MoO_(6) is extended and its bandgap narrowed.Oxygen vacancies not only lead to the appearance of a defect band level in the forbidden band but can also result in a minor up-shift of the valence band maximum,promoting the mobility of photogenerated holes.Moreover,oxygen vacancies can act as electron acceptors,temporarily capturing electrons excited by light and reducing the recombination of electrons and holes.At the same time,oxygen vacancies help to capture oxygen,which reacts with the captured photogenerated electrons to generate more superoxide radicals(·O_(2)-)to participate in the reaction,thereby significantly promoting the redox performance of the photocatalyst.From Bi_(2)MoO_(6) containing these oxygen vacancies(OVBMO),excellent photocatalytic performance has been obtained for the oxidation of 1,2,3,4-tetrahydroquinoline to produce quinoline and cause antibiotic degradation.The reaction mechanism of the oxidation of 1,2,3,4-tetrahydroquinoline to quinoline over the OVBMO materials is elucidated in terms of heterogeneous Catal.via a radical pathway.

Ag3PO4 Microcrystals Synthesized by Room-Temperature Solid State Reaction:Enhanced Photocatalytic Activity and Photoelectronchemistry Performance

Ag3PO4 microcrystals with highly enhanced visible light photocatalytic activity are prepared by a facile and simple solid state reaction at room temperature. The composition, morphology and optical properties of the asprepared Ag3PO4 microcrystMs are characterized by x-ray diffraction, scanning electron microscopy and UV-vis diffuse reflectance spectra. The photocatalytie properties of Ag3PO4 are investigated by the degradation of both methylene blue and methyl orange dyes under visible light irradiation. The as-prepared Ag3PO4 microcrystals possess high photocatalytic oxygen production with the rate of 673μmolh-1g-1. Moreover, the as-prepared Ag3PO4 microcrystals show an enhanced photoelectrochemistry performance under irradiation of visible light.

Solvent-assisted synthesis of porous g-C_3N_4 with efficient visible-light photocatalvtic performance for NO removal

Graphitic carbon nitride（g-C3N4） with efficient photocatalytic activity was synthesized through thermal polymerization of thiourea with the addition of water（CN-W） or ethanol（CN-E） at 550 ℃for 2 h.The physicochemical properties of the g-C3N4 were investigated by X-ray diffraction,transmission electron microscopy,ultraviolet-visible spectroscopy,photoluminescence spectroscopy,diffuse-reflection spectroscopy,BET and BJH surface area characterization,and elemental analysis.The carbon content was found to have self-doped into the g-C3N4 matrix during the thermal polymerization of thiourea and ethanol.CN-W and CN-E showed considerably enhanced visible-light photocatalytic activity,with NO removal percentages of 37.2%and 48.3%,respectively.Compared with pure g-C3N4,both the short and long lifetimes of the charge carriers in CN-W and CN-E were found to be prolonged.The mechanism of improved visible-light photocatalytic activity was deduced.The present work may provide a facile route to optimize the microstructure of g-C3N4photocatalysts for high-performance environmental and energy applications.

Design of(GO/TiO2)N one-dimensional photonic crystal photocatalysts with improved photocatalytic activity for tetracycline degradation

(GO/TiO2)N(GO represents graphene oxide,and N represents the period number of alternate superposition of two dielectrics)onedimensional photonic crystal with different lattice constants was prepared via the sol–gel technique,and its transmission characteristics for photocatalysis were tested.The results show that the lattice constant,filling ratio,number of periodic layers,and incident angle had effects on the band gap.When the lattice constant,filling ratio,number of periodic layers,and incident angle were set to 125 nm,0.45,21,and 0°,respectively,a gap width of 53 nm appeared at the central wavelength(322 nm).The absorption peak of the photocatalyst at 357 nm overlapped the blue edge of the photonic band gap.A slow photon effect region above 96%reflectivity appeared.The degradation rate of tetracycline in(GO/TiO2)N photonic crystal was enhanced to 64%within 60 min.Meanwhile,the degradation efficiency of(GO/TiO2)N one-dimensional photonic crystal was effectively improved compared with those of the GO/TiO2 composite film and GO/TiO2 powder.

Hydrothermal Synthesis of H_3PW_(12)O_(40)/TiO_2 Nanometer Photocatalyst and Its Catalytic Performance for Methyl Orange

H3PW12O40/TiO2 nanometer photocatalyst was prepared by one step hydrothermal synthesis from H3PW12O40·nH20 and Ti（OBu）4, simultaneously realizing the load and modification of H3PW12O40. The catalyst was characterized by Fourier transform infrared spectroscopy（FTIR）, powder X-ray diffraction（XRD）, nitrogen adsorp- tion-desorption analysis and scanning electron microscopy（SEM）. The results show that the catalyst is Keggin struc- ture and crystallized in anatase structure, the diameter and specific area of the prepared catalyst are 3.8 nm and 177.9 m^2/g, respectively, and its dispersity is better. The photocatalytic properties were compared for TiO2H3PW12O40/TiO2 prepared by impregnation and H3PW12O40/TiO2 prepared by hydrothermal method with methyl orange as a probe. The effects of H3PW12O40 loadings, crystallization method, initial pH and concentration of dye solution on the degradation of methyl orange were investigated.

Enhancing visible-light photocatalytic activity of α-Bi_2O_3 via non-metal N and S doping

In recent years, some important research indicated that the visible-light activity of photocatalysts could be enhanced via incorporating p-block non-metal elements into the lattice. In this paper, we investigated the electronic structures of pure and different non-metal （C, N, S, F, Cl, and Br） doped α-Bi2O3 using first-principles calculations based on the density functional theory. The band structures, the electronic densities of states, and the effective masses of electrons and holes for doped α-Bi2O3 were obtained and analyzed. The N and S dopings narrowed the band gap and reduced the effective mass of the carriers, which are beneficial for the photocatalytic performance. The theoretical predication was further confirmed by the experimental results.

Facile preparation of sepiolite@LDH composites for the visible-light degradation of organic dyes

Sepiolite@LDH(Sep@LDH)composites were designed and prepared based on the assembly of layered double hydroxides(LDH)on acidified sepiolites(Sep)for the simultaneous photocatalytic degradation of methyl orange(MO)and methylene blue(MB).The structure,morphology,texture,optical properties,and photocatalytic performance of the prepared Sep@LDH were studied in detail.Among the Sep@LDH composites,Sep4@LDH(4.0 g Sep)exhibited the highest photocatalytic activity under visible‐light irradiation,which could be attributed to its large surface area,high crystallinity,and plentiful active sites on its surface.The photodegradation of the dyes followed a pseudo first‐order kinetic model(Langmuir‐Hinshelwood model),indicating that the copious and homogeneous active sites on the surface of the composites contributed to the high photocatalytic activity.The photodegradation mechanism was studied by examining the active species(^-OH,h+,and·O2^-anions)using appropriate scavengers.It was found that·OH radicals played a critical role in the photocatalytic process of MO and MB,where the generation of·OH radicals occurred on the electron/hole(e^-/h+)pairs on the surface of the Sep@LDH composites.

Design of metal-organic frameworks(MOFs)-based photocatalyst for solar fuel production and photo-degradation of pollutants

Metal organic frameworks(MOFs)is a research hotspot in the solar fuel production and photo-degradation of pollutants field due to high surface area,rich metal/organic species,large pore volume,and adjustability of structures and compositions.Therefore,in this review,we first summarized the design factors of photocatalytic materials based on MOF from the perspective of"star"MOF.The modification strategies of MOFs-based photocatalysts were discussed to improve its photocatalytic activity and specific applications were summarized as well,including photocatalytic CO_(2)reduction,photocatalytic water splitting and photo-degradation of pollutants.Finally,the advantages and disadvantages of MOFs-based photocatalysts were discussed,the current challenges were highlighted,and suggestions for future research directions were proposed.

Low-cost and efficient visible-light-driven CaMg(CO_3)_2@Ag_2CO_3 microspheres fabricated via an ion exchange route

CaMg(CO3)2microspheres were prepared and used as hard templates to fabricate a series of CaMg(CO3)2@Ag2CO3composite microspheres via a fast and low‐cost ion exchange process.The effects of ion exchange time and temperature on the physicochemical properties and photocatalytic activities of the composite microspheres were studied through photocatalytic degradation of Acid Orange II under xenon lamp irradiation.The obtained samples were analyzed by X‐ray diffraction,scanning electron microscopy,Fourier transform infrared spectroscopy,UV‐vis diffuse reflectance spectroscopy,N2physical adsorption,and photocurrent tests.The CaMg(CO3)2@Ag2CO3sample with the highest activity was obtained with an ion exchange time of4h and temperature of40°C.The degradation rate of Acid Orange II by this sample reached83.3%after15min of light irradiation,and the sample also performed well in phenol degradation.The CaMg(CO3)2@Ag2CO3produced under these ion exchange conditions showed a well‐ordered hierarchical morphology with small particle sizes,which was beneficial to light absorption and the transfer of photoelectrons(e-)and holes(h+)to the catalyst surface.Moreover,the separation of photogenerated carriers over the composites was greatly improved relative to bare CaMg(CO3)2.Despite the very low content of Ag2CO3(2.56%),excellent photocatalytic performance was obtained over the CaMg(CO3)2@Ag2CO3microspheres.

Synthesis of defect-rich hierarchical sponge-like TiO2 nanoparticles and their improved photocatalytic and photoelectrochemical performance

Defect-rich hierarchical sponge-like TiO2 nanoparticles were successfully synthesized via the combined one-step hydrothermal method and chemical reduction approach.SEM and TEM images showed their porous structure densely packed with even smaller TiO2 particles,while photocatalytic results manifested their superior photocatalytic performance and high stability.The RhB solution(10 ppm)could be absolutely degraded in 60 min,and the degradation rate was twice that of the sample without the treatment by NaBH4.Besides,the TC solution(10 ppm)could be removed by 74.3%in 20 min.PEC measurements also displayed that the photoelectrode based on such defectrich TiO2 nanoparticles had small resistance and improved charge transfer rate.The improved performance can be assigned to rich defects and phase junctions,which was supported by characterization results.The presence of rich defects and phase junctions could not only promote the separation of photogenerated charge carriers,but also accelerate the electron transfer,beneficial for both the photocatalytic and the PEC performance.It is expected that the obtained hierarchical sponge-like TiO2 nanoparticles with rich defects have great potential for photocatalytic applications.

The metallic 1T-WS_(2)as cocatalysts for promoting photocatalytic N_(2) fixation performance of Bi_(5)O_(7)Br nanosheets

Recently,widespread attention has been devoted to the typical layered BiOCl or BiOBr because of the suitable nanostructure and band structure.However,owing to the fast carrier recombination,the photocatalytic performance of BiOX materials is not so satisfactory.Loading 1T phase WS_(2)nanosheets(NSs)onto Bi_(5)O_(7)Br NSs can improve the photocatalytic N_(2)fixation activity.Among these,the obtained 1T-WS_(2)@Bi_(5)O_(7)Br composites with optimum 5%1T-WS_(2)NSs display a significantly improved photocatalytic N_(2)fixation rate(8.43 mmol L^(−1)h^(−1)g^(−1)),2.51 times higher than pure Bi_(5)O_(7)Br(3.36 mmol L^(−1)h^(−1)g^(−1)).And the outstanding stability of 1T-WS_(2)@Bi_(5)O_(7)Br-5 composites is also achieved.Exactly,the photoexcited electrons from Bi_(5)O_(7)Br NSs are quickly transferred to conductive 1T phase WS_(2)as electron acceptors,which can promote the separation of carriers.In addition,1T-WS_(2)NSs can provide abundant active sites on the basal and edge planes,which can promote the efficiency of photocatalytic N_(2)fixation.This work offers a novel solution to improve the photocatalytic performance of Bi_(5)O_(7)Br NSs.