Bi_(2)O_(3)/BiOI step-scheme(S-scheme) heterojunction photocatalyst was synthesized by green calcination method, its degradation ability of methylene blue was investigated, and the photocatalytic performance of the Bi...Bi_(2)O_(3)/BiOI step-scheme(S-scheme) heterojunction photocatalyst was synthesized by green calcination method, its degradation ability of methylene blue was investigated, and the photocatalytic performance of the Bi_(2)O_(3)/BiOI heterojunction, Bi_(2)O_(3) and BiOI was compared. The structure and morphology of the samples were characterized by X-ray diffraction(XRD), field emission scanning electron microscopy(FESEM), and UV-vis diffuse reflection spectrum (UV-vis DRS). The degradation rate of methylene blue was analysised by spectrophotometry, and the calculation result showed that the degradation rate of methylene blue was 97.8% in 150 minutes. The first order kinetic rate constant of 10%Bi_(2)O_(3)/BiOI is 0.021 8 min^(-1), which are2.37 and 2.68 times of BiOI(0.009 18 min^(-1)) and Bi_(2)O_(3) (0.008 03 min^(-1)) respectively. The calculation result shows that the work function of Bi_(2)O_(3) and BiOI are 3.0 e V and 6.0 e V, respectively, by density functional theory(DFT). When this S-scheme heterojunction is used as a photocatalyst, the weaker electrons in the conduction band of BiOI will be combined with the weaker holes in the Bi_(2)O_(3) valence band under combined effect with built-in electric field and band bending, which will retain stronger photoelectrons and holes between Bi_(2)O_(3) and BiOI. This may be the internal reason for the efficient degradation of tetracycline by Bi_(2)O_(3)/BiOI S-scheme heterostructures.展开更多
Converting solar energy into chemical energy by artificial photosynthesis is promising in addressing the issues of the greenhouse effect and fossil fuel crisis.Herein,a novel photocatalyst,i.e.CdS/TiO_(2) hollow micro...Converting solar energy into chemical energy by artificial photosynthesis is promising in addressing the issues of the greenhouse effect and fossil fuel crisis.Herein,a novel photocatalyst,i.e.CdS/TiO_(2) hollow microspheres(HS),were dedicatedly designed to boost overall photocatalytic efficiency.TiO_(2) nanoparticles were in-situ decorated on the inside and outside the shell of Cd S HS,ensuring close contact between TiO_(2) and CdS.The CdS/TiO2 HS with abundant mesopores inside of the shell boost the light absorption via multiscattering effect as well as accessible to reactions in all directions.The heterojunction was scrutinized and the charge transfer across it was revealed by in-situ irradiated X-ray photoelectron spectroscopy(ISI-XPS).Ultimately,the charge transfer in this composite was determined to follow stepscheme mechanism,which not only facilitates the separation of charge carriers but also preserves strong redox ability.Benefited from the intimate linkage between Cd S and TiO_(2) and the favorable step-scheme heterojunction,enhanced photocatalytic CO_(2) reduction activity was accomplished.The CH4 yield rate of CdS/TiO_(2) reaches 27.85μmol g^(–1) h^(–1),which is 145.6 and 3.8 times higher than those of pristine CdS and TiO_(2),respectively.This work presents a novel insight into constructing step-scheme photocatalytic system with desirable performance.展开更多
The rational construction of a high-efficiency stepscheme heterojunctions is an effective strategy to accelerate the photocatalytic H_(2).Unfortunately,the variant energy-level matching between two different semicondu...The rational construction of a high-efficiency stepscheme heterojunctions is an effective strategy to accelerate the photocatalytic H_(2).Unfortunately,the variant energy-level matching between two different semiconductor confers limited the photocatalytic performance.Herein,a newfangled graphitic-carbon nitride(g-C_(3)N_(4))based isotype step-scheme heterojunction,which consists of sulfur-doped and defective active sites in one microstructural unit,is successfully developed by in-situ polymerizing N,N-dimethylformamide(DMF)and urea,accompanied by sulfur(S)powder.Therein,the polymerization between the amino groups of DMF and the amide group of urea endows the formation of rich defects.The propulsive integration of S-dopants contributes to the excellent fluffiness and dispersibility of lamellar g-C_(3)N_(4).Moreover,the developed heterojunction exhibits a significantly enlarged surface area,thus leading to the more exposed catalytically active sites.Most importantly,the simultaneous introduction of S-doping and defects in the units of g-C_(3)N_(4) also results in a significant improvement in the separation,transfer and recombination efficiency of photo-excited electron-hole pairs.Therefore,the resulting isotype step-scheme heterojunction possesses a superior photocatalytic H_(2) evolution activity in comparison with pristine g-C_(3)N_(4).The newly afforded metal-free isotype step-scheme heterojunction in this work will supply a new insight into coupling strategies of heteroatoms doping and defect engineering for various photocatalytic systems.展开更多
BiOCl as a representative layered bismuth-based photocatalyst with Sillén-structure has aroused wide public concern on photocatalytic degradation.However,the photocatalytic efficiency of pristine BiOCl is current...BiOCl as a representative layered bismuth-based photocatalyst with Sillén-structure has aroused wide public concern on photocatalytic degradation.However,the photocatalytic efficiency of pristine BiOCl is currently restricted by its low optical absorption and charge separation efficiency.Herein,step-scheme(S-scheme)heterojunctions of In_(2)O_(3) nanoparticle and BiOCl micron-sheet were constructed by a convenient molten salt method by using a LiNO_(3)-KNO_(3) system.The In_(2)O_(3)-BiOCl heterojunctions exhibit higher optical absorption performance from 380 nm to 700 nm than the pristine BiOCl and enhanced photocatalytic property toward ciprofloxacin(CIP)degradation under Xenon lamp illumination.The sample 20%In_(2)O_(3) -BiOCl showed the highest photodegradation efficiency,attaining 91%removal of CIP within 35 min,which was 39.6 times and 3.2 times higher than that of pristine In_(2)O_(3) and BiOCl,respectively.The improved photodegradation property mainly resulted from the novel S-scheme mechanism,which boosted highly efficient separation of the photo-induced carriers.The photoluminescence spectrometric test and transient photocurrent response results demonstrated that In_(2)O_(3)-BiOCl composite exhibited efficient separation of photo-generated charge carriers.This work would provide new insights into the design of novel S-scheme photocatalytic systems with applicability in photocatalytic water treatment.展开更多
Rational design and construction of step-scheme(S-scheme)photocatalyst has received much attention in the field of CO_(2) reduction because of its great potential to solve the current energy and environmental crises.I...Rational design and construction of step-scheme(S-scheme)photocatalyst has received much attention in the field of CO_(2) reduction because of its great potential to solve the current energy and environmental crises.In this study,a series of plate-like WO_(3)/CuBi_(2)O_(4)(WO/CBO)photocatalysts were synthesized.The CO and CH4 yields over optimal composite reached 1,115.8 and 67.2μmol/m2 after 9 h visible light illumination(λ>400 nm),which was higher than those of two pure catalysts in CO_(2) photoreduction.The product yields slightly decreased in the 7th cycling.Besides,the staggered band structure of heterojunction was characterized by diffuse reflectance spectroscopy(DRS)and valence band-X-ray photoelectron spectroscopy(VB-XPS),and a S-scheme charge transfer mechanism was verified by detecting electron spin resonance(ESR)and XPS result about surface composition of WO/CBO catalyst in dark or light.This work may be useful for rational designing of S-scheme photocatalyst and provides some illuminating insights into the S-scheme transfer mechanism.展开更多
基金Funded by National Natural Science Foundation of China (No.21769009)Project of Innovation and Entrepreneurship for College Students in Hubei Minzu University (No.S202010517044)+2 种基金The foundation of Key Laboratory of Green Manufacturing of Super-light Elastomer Materials of State Ethnic Affairs Commission.(Hubei Minzu University)(No.PT092101)The Open Project of Guangxi Key Laboratory of Chemistry and Engineering of Forest Products(No.GXFK1904)Specific Research Project of Guangxi for Research Bases and Talents(No.AD18126005)。
文摘Bi_(2)O_(3)/BiOI step-scheme(S-scheme) heterojunction photocatalyst was synthesized by green calcination method, its degradation ability of methylene blue was investigated, and the photocatalytic performance of the Bi_(2)O_(3)/BiOI heterojunction, Bi_(2)O_(3) and BiOI was compared. The structure and morphology of the samples were characterized by X-ray diffraction(XRD), field emission scanning electron microscopy(FESEM), and UV-vis diffuse reflection spectrum (UV-vis DRS). The degradation rate of methylene blue was analysised by spectrophotometry, and the calculation result showed that the degradation rate of methylene blue was 97.8% in 150 minutes. The first order kinetic rate constant of 10%Bi_(2)O_(3)/BiOI is 0.021 8 min^(-1), which are2.37 and 2.68 times of BiOI(0.009 18 min^(-1)) and Bi_(2)O_(3) (0.008 03 min^(-1)) respectively. The calculation result shows that the work function of Bi_(2)O_(3) and BiOI are 3.0 e V and 6.0 e V, respectively, by density functional theory(DFT). When this S-scheme heterojunction is used as a photocatalyst, the weaker electrons in the conduction band of BiOI will be combined with the weaker holes in the Bi_(2)O_(3) valence band under combined effect with built-in electric field and band bending, which will retain stronger photoelectrons and holes between Bi_(2)O_(3) and BiOI. This may be the internal reason for the efficient degradation of tetracycline by Bi_(2)O_(3)/BiOI S-scheme heterostructures.
基金financially supported by the National Natural Science Foundation of China(NSFC)(Nos.51872220,51932007,51961135303,21871217,U1905215 and U1705251)the National Key Research and Development Program of China(No.2018YFB1502001)the Fundamental Research Funds for the Central Universities(No.WUT:2019IVB050)。
文摘Converting solar energy into chemical energy by artificial photosynthesis is promising in addressing the issues of the greenhouse effect and fossil fuel crisis.Herein,a novel photocatalyst,i.e.CdS/TiO_(2) hollow microspheres(HS),were dedicatedly designed to boost overall photocatalytic efficiency.TiO_(2) nanoparticles were in-situ decorated on the inside and outside the shell of Cd S HS,ensuring close contact between TiO_(2) and CdS.The CdS/TiO2 HS with abundant mesopores inside of the shell boost the light absorption via multiscattering effect as well as accessible to reactions in all directions.The heterojunction was scrutinized and the charge transfer across it was revealed by in-situ irradiated X-ray photoelectron spectroscopy(ISI-XPS).Ultimately,the charge transfer in this composite was determined to follow stepscheme mechanism,which not only facilitates the separation of charge carriers but also preserves strong redox ability.Benefited from the intimate linkage between Cd S and TiO_(2) and the favorable step-scheme heterojunction,enhanced photocatalytic CO_(2) reduction activity was accomplished.The CH4 yield rate of CdS/TiO_(2) reaches 27.85μmol g^(–1) h^(–1),which is 145.6 and 3.8 times higher than those of pristine CdS and TiO_(2),respectively.This work presents a novel insight into constructing step-scheme photocatalytic system with desirable performance.
基金This work was supported by the National Natural Science Foundation of China(No.62004143)the Central Government Guided Local Science and Technology Development Special Fund Project(No.2020ZYYD033)+4 种基金the Natural Science Foundation of Hubei Province(No.2021CFB133)the Opening Fund of Key Laboratory of Rare Mineral Ministry of Natural Resources(No.KLRM-KF 202005)the Open Research Fund of Key Laboratory of Material Chemistry for Energy Conversion and Storage(HUST),Ministry of Education(No.2021JYBKF05)the Opening Fund of Key Laboratory for Green Chemical Process of Ministry of Education of Wuhan Institute of Technology(No.GCP202101)the Innovation Project of Engineering Research Center of Phosphorus Resources Development and Utilization of Ministry of Education(No.LCX2021003)。
文摘The rational construction of a high-efficiency stepscheme heterojunctions is an effective strategy to accelerate the photocatalytic H_(2).Unfortunately,the variant energy-level matching between two different semiconductor confers limited the photocatalytic performance.Herein,a newfangled graphitic-carbon nitride(g-C_(3)N_(4))based isotype step-scheme heterojunction,which consists of sulfur-doped and defective active sites in one microstructural unit,is successfully developed by in-situ polymerizing N,N-dimethylformamide(DMF)and urea,accompanied by sulfur(S)powder.Therein,the polymerization between the amino groups of DMF and the amide group of urea endows the formation of rich defects.The propulsive integration of S-dopants contributes to the excellent fluffiness and dispersibility of lamellar g-C_(3)N_(4).Moreover,the developed heterojunction exhibits a significantly enlarged surface area,thus leading to the more exposed catalytically active sites.Most importantly,the simultaneous introduction of S-doping and defects in the units of g-C_(3)N_(4) also results in a significant improvement in the separation,transfer and recombination efficiency of photo-excited electron-hole pairs.Therefore,the resulting isotype step-scheme heterojunction possesses a superior photocatalytic H_(2) evolution activity in comparison with pristine g-C_(3)N_(4).The newly afforded metal-free isotype step-scheme heterojunction in this work will supply a new insight into coupling strategies of heteroatoms doping and defect engineering for various photocatalytic systems.
基金the National Nature Science Foundation of China(No.21871030,52174238)Hunan Provincial Natural Science Foundation of China(No.2020JJ4644,2018JJ2456)the Research Foundation of Education Bureau of Hunan Provincial(No.19A053,19B062)。
文摘BiOCl as a representative layered bismuth-based photocatalyst with Sillén-structure has aroused wide public concern on photocatalytic degradation.However,the photocatalytic efficiency of pristine BiOCl is currently restricted by its low optical absorption and charge separation efficiency.Herein,step-scheme(S-scheme)heterojunctions of In_(2)O_(3) nanoparticle and BiOCl micron-sheet were constructed by a convenient molten salt method by using a LiNO_(3)-KNO_(3) system.The In_(2)O_(3)-BiOCl heterojunctions exhibit higher optical absorption performance from 380 nm to 700 nm than the pristine BiOCl and enhanced photocatalytic property toward ciprofloxacin(CIP)degradation under Xenon lamp illumination.The sample 20%In_(2)O_(3) -BiOCl showed the highest photodegradation efficiency,attaining 91%removal of CIP within 35 min,which was 39.6 times and 3.2 times higher than that of pristine In_(2)O_(3) and BiOCl,respectively.The improved photodegradation property mainly resulted from the novel S-scheme mechanism,which boosted highly efficient separation of the photo-induced carriers.The photoluminescence spectrometric test and transient photocurrent response results demonstrated that In_(2)O_(3)-BiOCl composite exhibited efficient separation of photo-generated charge carriers.This work would provide new insights into the design of novel S-scheme photocatalytic systems with applicability in photocatalytic water treatment.
基金supported by the financial supports of National Natural Science Foundation of China(Nos.51802082 and 51903073)Natural Science Foundation of Henan Province(No.212300410221)+4 种基金Program for Science&Technology Innovation Talents in Universities of Henan Province(No.21HATIT016)Key Scientific Research Project of Colleges and Universities in Henan Province(Nos.21A430030 and 20A150017)Key Scientific and Technological Project of Henan Province(Nos.222102320100,212102210473,and 212102210178)National College Student Innovantion and Entrepreneurship Training(No.202110467024)“Climbing”Project of Henan Institute of Science and Technology(No.2018CG04).
文摘Rational design and construction of step-scheme(S-scheme)photocatalyst has received much attention in the field of CO_(2) reduction because of its great potential to solve the current energy and environmental crises.In this study,a series of plate-like WO_(3)/CuBi_(2)O_(4)(WO/CBO)photocatalysts were synthesized.The CO and CH4 yields over optimal composite reached 1,115.8 and 67.2μmol/m2 after 9 h visible light illumination(λ>400 nm),which was higher than those of two pure catalysts in CO_(2) photoreduction.The product yields slightly decreased in the 7th cycling.Besides,the staggered band structure of heterojunction was characterized by diffuse reflectance spectroscopy(DRS)and valence band-X-ray photoelectron spectroscopy(VB-XPS),and a S-scheme charge transfer mechanism was verified by detecting electron spin resonance(ESR)and XPS result about surface composition of WO/CBO catalyst in dark or light.This work may be useful for rational designing of S-scheme photocatalyst and provides some illuminating insights into the S-scheme transfer mechanism.
