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
In recent years,environmental pollution and energy crisis have become increasingly serious issues owing to the burning of fossil fuels.Among the many technologies,decomposition of water to produce hydrogen has attract...In recent years,environmental pollution and energy crisis have become increasingly serious issues owing to the burning of fossil fuels.Among the many technologies,decomposition of water to produce hydrogen has attracted much attention because of its sustainability and non-polluting characteristic.However,highly efficient decomposition of water that is driven by visible light is still a challenge.Herein,we report the large-scale preparation of step-scheme porous graphite carbon nitride/Zn0.2Cd0.8S-diethylenetriamine(Pg-C3N4/Zn0.2Cd0.8S-DETA)composite by a facile solvothermal method.It was found by UV-vis spectroscopy that 15%Pg-C3N4/Zn0.2Cd0.8S-DETA exhibited suitable visible absorption edge and band gap for water decomposition.The hydrogen production rate of 15%Pg-C3N4/Zn0.2Cd0.8S-DETA composite was 6.69 mmol g^-1 h^-1,which was 16.73,1.61,and 1.44 times greater than those of Pg-C3N4,CdS-DETA,and Zn0.2Cd0.8S-DETA,respectively.In addition,15%Pg-C3N4/Zn0.2Cd0.8S-DETA composite displayed excellent photocatalytic stability,which was maintained for seven cycles of photocatalytic water splitting test.We believe that 15%Pg-C3N4/Zn0.2Cd0.8S-DETA composite can be a valuable guide for the development of solar hydrogen production applications in the near future.展开更多
Over the past few years,the emission of organic pollutants into the environment has increased tremendously.Therefore,various photocatalysts have been developed for the degradation of organic pollutants.In this study,a...Over the past few years,the emission of organic pollutants into the environment has increased tremendously.Therefore,various photocatalysts have been developed for the degradation of organic pollutants.In this study,a step-scheme BiVO4/Ag3VO4 composite was synthesized via a hydrothermal and chemical deposition process for the degradation of methylene blue.The composite showed strong redox ability under visible light.The 40%BiVO4/Ag3VO4 composite showed excellent photocatalytic degradation properties with a Kapp of 0.05588 min^–1,which is 22.76 and 1.76 times higher than those of BiVO4(0.00247 min^–1)and Ag3VO4(0.03167 min^–1),respectively.The composite showed a stable performance and could retain 90%of its photocatalytic activity even after four cycles.The improved catalytic performance of the composite as compared to BiVO4 and Ag3VO4 can be attributed to its novel step-scheme mechanism,which facilitated the separation of the photogenerated charges and increased their lifetime.The photoluminescence measurement results and transient photocurrent response revealed that the composite showed efficient extraction of charge carriers.展开更多
Constructing a step-scheme heterojunction at the interface between two semiconductors is an efficient way to optimize the redox ability and accelerate the charge carrier separation of a photocatalytic system for achie...Constructing a step-scheme heterojunction at the interface between two semiconductors is an efficient way to optimize the redox ability and accelerate the charge carrier separation of a photocatalytic system for achieving high photocatalytic performance.In this study,we prepared a hierarchical ZnO@ZnS step-scheme photocatalyst by incorporating ZnS into the outer shell of hollow ZnO microspheres via a simple in situ sulfidation strategy.The ZnO@ZnS step-scheme photocatalysts had a large surface area,high light utilization capacity,and superior separation efficiency for photogenerated charge carriers.In addition,the material simulation revealed that the formation of the step-scheme heterojunction between ZnO and ZnS was due to the presence of the built-in electric field.Our study paves the way for design of high-performance photocatalysts for H_(2) production.展开更多
In this study,a step-scheme photocatalytic system comprising one-dimensional In_(2)O_(3)nanorods and two-dimensional ZnIn_(2)S_(4)nanosheets was developed for the catalytic photofixation of nitrogen.The effects of the...In this study,a step-scheme photocatalytic system comprising one-dimensional In_(2)O_(3)nanorods and two-dimensional ZnIn_(2)S_(4)nanosheets was developed for the catalytic photofixation of nitrogen.The effects of the combination of In_(2)O_(3)with ZnIn_(2)S_(4)on the crystallinity,microstructure,optical absorption,and charge transfer behavior of the In_(2)O_(3)/ZnIn_(2)S_(4)hybrid photocatalysts were investigated.Benefiting from the synergistic effects of the photogenerated vacancies and a step-scheme charge separation mechanism,the In_(2)O_(3)/ZnIn_(2)S_(4)hybrid photocatalyst exhibited significantly enhanced catalytic activity compared to those of bare In_(2)O_(3)and pure ZnIn_(2)S_(4),and an optimized 50 wt%In_(2)O_(3)/ZnIn_(2)S_(4)hybrid sample was found to exhibit superior catalytic activity for the photofixation of N2,fixing 18.1±0.77 mg·L-1 of ammonia after exposure to simulated sunlight for 2 h.Crucially,the results of trapping experiments and electron paramagnetic resonance investigation to identify the active species confirmed that the catalytic nitrogen photofixation performance was highly correlated with the presence of·CO_(2)-radicals rather than photogenerated electrons,especially when methanol was used as a hole scavenger.In summary,the reported In_(2)O_(3)/ZnIn_(2)S_(4)hybrid photocatalysts exhibit both stability and high activity for the photofixation of N_(2),making them promising catalysts for sunlight-driven artificial N_(2)fixation.展开更多
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
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
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
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
Hydrogen peroxide(H_(2)O_(2)),as an essential and green chemical,is extensively used in energy and environmental applications.However,the production of H_(2)O_(2)primarily relies on the anthraquinone method,which is a...Hydrogen peroxide(H_(2)O_(2)),as an essential and green chemical,is extensively used in energy and environmental applications.However,the production of H_(2)O_(2)primarily relies on the anthraquinone method,which is an energy-intensive method involving multi-step reactions,producing harmful by-product wastes.Solar-driven H_(2)O_(2)production,an alternative route for H_(2)O_(2)generation,is a green and sustainable technology since it only utilizes water and oxygen as feedstock.However,the rapid recombination of charge carriers as well as insufficient redox capability limit the photocatalytic H_(2)O_(2)production performance.Constructing step-scheme(S-scheme)heterojunction photocatalysts has been regarded as an effective strategy to address these drawbacks because it not only achieves spatially separated charge carriers,but also preserves redox capability of the photocatalytic system.This paper covers the recent advances of S-scheme heterojunction photocatalysts for H_(2)O_(2)production in terms of basic principles,characterization techniques,and preparation strategies.Moreover,the mechanism and advantages of S-scheme heterojunction for photocatalytic H_(2)O_(2)generation are systematically discussed.The recent S-scheme heterojunction designs,including inorganic-organic heterojunction,inorganic-inorganic heterojunction,and organic-organic heterojunction,are summarized.Lastly,the challenges and research directions of S-scheme photocatalysts for H_(2)O_(2)generation are presented.展开更多
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supported by the National Natural Science Foundation of China(51572103,51502106)the Distinguished Young Scholar of Anhui Province(1808085J14)+2 种基金the Foundation for Young Talents in College of Anhui Province(gxyqZD2017051)the Key Foundation of Educational Commission of Anhui Province(KJ2016SD53)Innovation Team of Design and Application of Advanced Energetic Materials(KJ2015TD003)~~
文摘In recent years,environmental pollution and energy crisis have become increasingly serious issues owing to the burning of fossil fuels.Among the many technologies,decomposition of water to produce hydrogen has attracted much attention because of its sustainability and non-polluting characteristic.However,highly efficient decomposition of water that is driven by visible light is still a challenge.Herein,we report the large-scale preparation of step-scheme porous graphite carbon nitride/Zn0.2Cd0.8S-diethylenetriamine(Pg-C3N4/Zn0.2Cd0.8S-DETA)composite by a facile solvothermal method.It was found by UV-vis spectroscopy that 15%Pg-C3N4/Zn0.2Cd0.8S-DETA exhibited suitable visible absorption edge and band gap for water decomposition.The hydrogen production rate of 15%Pg-C3N4/Zn0.2Cd0.8S-DETA composite was 6.69 mmol g^-1 h^-1,which was 16.73,1.61,and 1.44 times greater than those of Pg-C3N4,CdS-DETA,and Zn0.2Cd0.8S-DETA,respectively.In addition,15%Pg-C3N4/Zn0.2Cd0.8S-DETA composite displayed excellent photocatalytic stability,which was maintained for seven cycles of photocatalytic water splitting test.We believe that 15%Pg-C3N4/Zn0.2Cd0.8S-DETA composite can be a valuable guide for the development of solar hydrogen production applications in the near future.
文摘Over the past few years,the emission of organic pollutants into the environment has increased tremendously.Therefore,various photocatalysts have been developed for the degradation of organic pollutants.In this study,a step-scheme BiVO4/Ag3VO4 composite was synthesized via a hydrothermal and chemical deposition process for the degradation of methylene blue.The composite showed strong redox ability under visible light.The 40%BiVO4/Ag3VO4 composite showed excellent photocatalytic degradation properties with a Kapp of 0.05588 min^–1,which is 22.76 and 1.76 times higher than those of BiVO4(0.00247 min^–1)and Ag3VO4(0.03167 min^–1),respectively.The composite showed a stable performance and could retain 90%of its photocatalytic activity even after four cycles.The improved catalytic performance of the composite as compared to BiVO4 and Ag3VO4 can be attributed to its novel step-scheme mechanism,which facilitated the separation of the photogenerated charges and increased their lifetime.The photoluminescence measurement results and transient photocurrent response revealed that the composite showed efficient extraction of charge carriers.
文摘Constructing a step-scheme heterojunction at the interface between two semiconductors is an efficient way to optimize the redox ability and accelerate the charge carrier separation of a photocatalytic system for achieving high photocatalytic performance.In this study,we prepared a hierarchical ZnO@ZnS step-scheme photocatalyst by incorporating ZnS into the outer shell of hollow ZnO microspheres via a simple in situ sulfidation strategy.The ZnO@ZnS step-scheme photocatalysts had a large surface area,high light utilization capacity,and superior separation efficiency for photogenerated charge carriers.In addition,the material simulation revealed that the formation of the step-scheme heterojunction between ZnO and ZnS was due to the presence of the built-in electric field.Our study paves the way for design of high-performance photocatalysts for H_(2) production.
文摘In this study,a step-scheme photocatalytic system comprising one-dimensional In_(2)O_(3)nanorods and two-dimensional ZnIn_(2)S_(4)nanosheets was developed for the catalytic photofixation of nitrogen.The effects of the combination of In_(2)O_(3)with ZnIn_(2)S_(4)on the crystallinity,microstructure,optical absorption,and charge transfer behavior of the In_(2)O_(3)/ZnIn_(2)S_(4)hybrid photocatalysts were investigated.Benefiting from the synergistic effects of the photogenerated vacancies and a step-scheme charge separation mechanism,the In_(2)O_(3)/ZnIn_(2)S_(4)hybrid photocatalyst exhibited significantly enhanced catalytic activity compared to those of bare In_(2)O_(3)and pure ZnIn_(2)S_(4),and an optimized 50 wt%In_(2)O_(3)/ZnIn_(2)S_(4)hybrid sample was found to exhibit superior catalytic activity for the photofixation of N2,fixing 18.1±0.77 mg·L-1 of ammonia after exposure to simulated sunlight for 2 h.Crucially,the results of trapping experiments and electron paramagnetic resonance investigation to identify the active species confirmed that the catalytic nitrogen photofixation performance was highly correlated with the presence of·CO_(2)-radicals rather than photogenerated electrons,especially when methanol was used as a hole scavenger.In summary,the reported In_(2)O_(3)/ZnIn_(2)S_(4)hybrid photocatalysts exhibit both stability and high activity for the photofixation of N_(2),making them promising catalysts for sunlight-driven artificial N_(2)fixation.
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.
文摘Hydrogen peroxide(H_(2)O_(2)),as an essential and green chemical,is extensively used in energy and environmental applications.However,the production of H_(2)O_(2)primarily relies on the anthraquinone method,which is an energy-intensive method involving multi-step reactions,producing harmful by-product wastes.Solar-driven H_(2)O_(2)production,an alternative route for H_(2)O_(2)generation,is a green and sustainable technology since it only utilizes water and oxygen as feedstock.However,the rapid recombination of charge carriers as well as insufficient redox capability limit the photocatalytic H_(2)O_(2)production performance.Constructing step-scheme(S-scheme)heterojunction photocatalysts has been regarded as an effective strategy to address these drawbacks because it not only achieves spatially separated charge carriers,but also preserves redox capability of the photocatalytic system.This paper covers the recent advances of S-scheme heterojunction photocatalysts for H_(2)O_(2)production in terms of basic principles,characterization techniques,and preparation strategies.Moreover,the mechanism and advantages of S-scheme heterojunction for photocatalytic H_(2)O_(2)generation are systematically discussed.The recent S-scheme heterojunction designs,including inorganic-organic heterojunction,inorganic-inorganic heterojunction,and organic-organic heterojunction,are summarized.Lastly,the challenges and research directions of S-scheme photocatalysts for H_(2)O_(2)generation are presented.
