Sunlight-driven photocatalytic water-splitting for hydrogen(H2)evolution is a desirable strategy to utilize solar energy.However,this strategy is restricted by insufficient light harvesting and high photogenerated ele...Sunlight-driven photocatalytic water-splitting for hydrogen(H2)evolution is a desirable strategy to utilize solar energy.However,this strategy is restricted by insufficient light harvesting and high photogenerated electron-hole recombination rates of TiO2-based photocatalysts.Here,a graphene-modified WO3/TiO2 step-scheme heterojunction(S-scheme heterojunction)composite photocatalyst was fabricated by a facile one-step hydrothermal method.In the ternary composite,TiO2 and WO3 nanoparticles adhered closely to reduced graphene oxide(rGO)and formed a novel S-scheme heterojunction.Moreover,rGO in the composite not only supplied abundant adsorption and catalytically active sites as an ideal support but also promoted electron separation and transfer from the conduction band of TiO2 by forming a Schottky junction between TiO2 and rGO.The positive cooperative effect of the S-scheme heterojunction formed between WO3 and TiO2 and the Schottky heterojunction formed between TiO2 and graphene sheets suppressed the recombination of relatively useful electrons and holes.This effect also enhanced the light harvesting and promoted the reduction reaction at the active sites.Thus,the novel ternary WO3/TiO2/rGO composite demonstrated a remarkably enhanced photocatalytic H2 evolution rate of 245.8μmol g^-1 h^-1,which was approximately 3.5-fold that of pure TiO2.This work not only presents a low-cost graphene-based S-scheme heterojunction photocatalyst that was obtained via a feasible one-step hydrothermal approach to realize highly efficient H2 generation without using noble metals,but also provides new insights into the design of novel heterojunction photocatalysts.展开更多
With the significant discharge of antibiotic wastewater into the aquatic and terrestrial ecosystems, antibiotic pollution has become a serious problem and presents a hazardous risk to the environment. To address such ...With the significant discharge of antibiotic wastewater into the aquatic and terrestrial ecosystems, antibiotic pollution has become a serious problem and presents a hazardous risk to the environment. To address such issues, various investigations on the removal of antibiotics have been undertaken. Photocatalysis has received tremendous attention owing to its great potential in removing antibiotics from aqueous solutions via a green, economic, and effective process. However, such a technology employing traditional photocatalysts suffers from major drawbacks such as light absorption being restricted to the UV spectrum only and fast charge recombination. To overcome these issues, considerable effort has been directed towards the development of advanced visible light-driven photocatalysts. This mini review summarises recent research progress in the state-of-the-art design and fabrication of photocatalysts with visible-light response for photocatalytic degradation of antibiotic wastewater. Such design strategies involve the doping of metal and non-metal into ultraviolet light-driven photocatalysts, development of new semiconductor photocatalysts, construction of heterojunction photocatalysts, and fabrication of surface plasmon resonance-enhanced photocatalytic systems. Additionally, some perspectives on the challenges and future developments in the area of photocatalytic degradation of antibiotics are provided.展开更多
Constructing step-scheme(S-scheme)heterojunctions has been confirmed as a promising strategy for enhancing the photocatalytic activity of composite materials.In this work,a series of sulfur-doped g-C3N4(SCN)/TiO2 S-sc...Constructing step-scheme(S-scheme)heterojunctions has been confirmed as a promising strategy for enhancing the photocatalytic activity of composite materials.In this work,a series of sulfur-doped g-C3N4(SCN)/TiO2 S-scheme photocatalysts were synthesized using electrospinning and calcination methods.The as-prepared SCN/TiO2 composites showed superior photocatalytic performance than pure TiO2 and SCN in the photocatalytic degradation of Congo Red(CR)aqueous solution.The significant enhancement in photocatalytic activity benefited not only from the 1D well-distributed nanostructure,but also from the S-scheme heterojunction.Furthermore,the XPS analyses and DFT calculations demonstrated that electrons were transferred from SCN to TiO2 across the interface of the SCN/TiO2 composites.The built-in electric field,band edge bending,and Coulomb interaction synergistically facilitated the recombination of relatively useless electrons and holes in hybrid when the interface was irradiated by simulated solar light.Therefore,the remaining electrons and holes with higher reducibility and oxidizability endowed the composite with supreme redox ability.These results were adequately verified by radical trapping experiments,ESR tests,and in situ XPS analyses,suggesting that the electron immigration in the photocatalyst followed the S-scheme heterojunction mechanism.This work can enrich our knowledge of the design and fabrication of novel S-scheme heterojunction photocatalysts and provide a promising strategy for solving environmental pollution in the future.展开更多
Semiconductor heterojunction photocatalysts have received much concern due to their great application prospect in solar energy utilization and conversion.Rational construction of heterostructure with two or more semic...Semiconductor heterojunction photocatalysts have received much concern due to their great application prospect in solar energy utilization and conversion.Rational construction of heterostructure with two or more semiconductor materials can integrate the advantages of multi-components to simultaneously improve the photo-induced charges separation,extend visible light absorption range and retain the high redox ability of photocatalysts.Recently,constructing of g-C3 N4-based heterostructure has become a hot focus due to the multiple merits of g-C3 N4,such as facile synthesis,high stability,unique optical and electronic characteristics.This review tries to give a comprehensive introduction and provide the possible tendency in design and fabrication of g-C3 N4-based heterojunction photocatalysts,especially in rational synthesis of type-II heterojunction,direct Z-scheme heterojunction,new type of S-scheme heterojunction,p-n heterojunction and Schottky heterojunction.Furthermore,the special charges transfer mechanisms of g-C3 N4-based heterojunctions are discussed and their potential applications in photocatalytic water splitting,photo-degradation of contaminants and photo-reduction of CO2 into fuels are also summarized.Finally,we attempt to propose some crucial issues based on the current research,which should be further investigated and resolved in this interesting research area.展开更多
Recently,a new opinion was put forward on general design standards for S-scheme heterojunction photocatalyst.Four types of S-scheme heterojunctions were analyzed.Specifically,the critical understanding on the curved F...Recently,a new opinion was put forward on general design standards for S-scheme heterojunction photocatalyst.Four types of S-scheme heterojunctions were analyzed.Specifically,the critical understanding on the curved Fermi level at the interface of S-scheme heterojunction is helpful to strengthen and promote the basic theory of photocatalysis.展开更多
Organic-inorganic hybrid perovskite(OIHP)photodetectors that simultaneously achieve an ultrafast response and high sensitivity in the near-infrared(NIR)region are prerequisites for expanding current monitoring,imaging...Organic-inorganic hybrid perovskite(OIHP)photodetectors that simultaneously achieve an ultrafast response and high sensitivity in the near-infrared(NIR)region are prerequisites for expanding current monitoring,imaging,and optical communication capbilities.Herein,we demonstrate photodetectors constructed by OIHP and an organic bulk heterojunction(BHJ)consisting of a low-bandgap nonfullerene and polymer,which achieve broadband response spectra up to 1μm with a highest external quantum efficiency of approximately 54%at 850 nm,an ultrafast response speed of 5.6 ns and a linear dynamic range(LDR)of 191 dB.High sensitivity,ultrafast speed and a large LDR are preeminent prerequisites for the practical application of photodetectors.Encouragingly,due to the high-dynamicrange imaging capacity,high-quality visible-NIR actual imaging is achieved by employing the OIHP photodetectors.We believe that state-of-the-art OIHP photodetectors can accelerate the translation of solution-processed photodetector applications from the laboratory to the imaging market.展开更多
对B+注入的n on p平面结和分子束外延 (MBE)技术原位铟掺杂的n+ n p台面异质结的碲镉汞 (HgCdTe)长波光伏探测器暗电流进行了对比分析 .与n on p平面结器件相比 ,原位掺杂的n+ n p台面异质结器件得到较高的零偏动态阻抗 面积值 (R0 A) ...对B+注入的n on p平面结和分子束外延 (MBE)技术原位铟掺杂的n+ n p台面异质结的碲镉汞 (HgCdTe)长波光伏探测器暗电流进行了对比分析 .与n on p平面结器件相比 ,原位掺杂的n+ n p台面异质结器件得到较高的零偏动态阻抗 面积值 (R0 A) .通过与实验数据拟合 ,从理论上计算了这两种结构的器件在不同温度下的R0 A和在不同偏压下的暗电流 。展开更多
The research of ultraviolet photodetectors(UV PDs)have been attracting extensive attention,due to their important applications in many areas.In this study,PtSe2/GaN heterojunction is in-situ fabricated by synthesis of...The research of ultraviolet photodetectors(UV PDs)have been attracting extensive attention,due to their important applications in many areas.In this study,PtSe2/GaN heterojunction is in-situ fabricated by synthesis of large-area vertically standing two-dimensional(2D)PtSe2 film on n-GaN substrate.The PtSe2/GaN heterojunction device demonstrates excellent photoresponse properties under illumination by deep UV light of 265 nm at zero bias voltage.Further analysis reveals that a high responsivity of 193 mA·W^-1,an ultrahigh specific detectivity of 3.8 × 10^14 Jones,linear dynamic range of 155d B and current on/off ratio of^10^8,as well as fast response speeds of 45/102μs were obtained at zero bias voltage.Moreover,this device response quickly to the pulse laser of 266 nm with a rise time of 172 ns.Such high-performanee PtSe2/GaN heteroj u nction UV PD demonstrated in this work is far superior to previously reported results,suggesting that it has great potential for deep UV detection.展开更多
The rapid recombination of photo-generated electron-hole pairs,insufficient active sites,and strong photocorrosion have considerably restricted the practical application of Cd S in photocatalytic fields.Herein,we desi...The rapid recombination of photo-generated electron-hole pairs,insufficient active sites,and strong photocorrosion have considerably restricted the practical application of Cd S in photocatalytic fields.Herein,we designed and constructed a 2D/2D/2D layered heterojunction photocatalyst with cascaded 2D coupling interfaces.Experiments using electron spin resonance spectroscopy,ultraviolet photoelectron spectroscopy,and in-situ irradiation X-ray photoelectron spectroscopy were conducted to confirm the 2D layered CdS/WO_(3) step-scheme(S-scheme)heterojunctions and CdS/MX ohmic junctions.Impressively,it was found that the strong interfacial electric fields in the S-scheme heterojunction photocatalysts could effectively promote spatially directional charge separation and transport between CdS and WO_(3) nanosheets.In addition,2D Ti_(3)C_(2) MXene nanosheets with a smaller work function and excellent metal conductivity when used as a co-catalyst could build ohmic junctions with Cd S nanosheets,thus providing a greater number of electron transfer pathways and hydrogen evolution sites.Results showed that the highest visible-light hydrogen evolution rate of the optimized MX-Cd S/WO_(3) layered multi-heterostructures could reach as high as 27.5 mmol/g/h,which was 11.0 times higher than that of pure CdS nanosheets.Notably,the apparent quantum efficiency reached 12.0% at 450 nm.It is hoped that this study offers a reliable approach for developing multifunctional photocatalysts by integrating S-scheme and ohmic-junction built-in electric fields and rationally designing a 2D/2D interface for efficient light-to-hydrogen fuel production.展开更多
The design and construction of heterojunction photocatalysts,which possess a staggered energy band structure and appropriate interfacial contact,is an effective way to achieve outstanding photocatalytic performance.In...The design and construction of heterojunction photocatalysts,which possess a staggered energy band structure and appropriate interfacial contact,is an effective way to achieve outstanding photocatalytic performance.In this study,2D/2D BiOBr/g‐C_(3)N_(4)heterojunctions were successfully obtained by a convenient in situ self‐assembly route.Under simulated sunlight irradiation,99%of RhB(10 mg·L–1,100 mL)was efficiently degraded by 1.5‐BiOBr/g‐C_(3)N_(4)within 30 min,which is better than the performance of both BiOBr and g‐C_(3)N_(4),and it has superior stability.In addition,the composite also exhibits enhanced photocatalytic activity for H2 production.The enhanced activity can be attributed to the intimate interface contact,the larger surface area,and the highly efficient separation of photoinduced electron–hole pairs.Based on the experimental results,a novel S‐scheme model was proposed to illuminate the transfer process of charge carriers.This study presents a simple way to develop novel step‐scheme photocatalysts for environmental and related applications.展开更多
Converting sustainable solar energy into hydrogen energy over semiconductor-based photocatalytic materials provides an alternative to fossil fuel consumption.However,efficient photocatalytic splitting of water to real...Converting sustainable solar energy into hydrogen energy over semiconductor-based photocatalytic materials provides an alternative to fossil fuel consumption.However,efficient photocatalytic splitting of water to realize carbon-free hydrogen production remains a challenge.Heterojunction photocatalysts with well-defined dimensionality and perfectly matched interfaces are promising for achieving highly efficient solar-to-hydrogen conversion.Herein,we report the fabrication of a novel type of protonated graphitic carbon nitride(PCN)/Ti3C2 MXene heterojunctions with strong interfacial interactions.As expected,the two-dimensional(2D)PCN/2D Ti3C2 MXene interface heterojunction achieves a highly improved hydrogen evolution rate(2181μmol∙g‒1)in comparison with bulk g-C3N4(393μmol∙g‒1)and protonated g-C3N4(816μmol∙g‒1).The charge-regulated surfaces of PCN and the accelerated charge transport at the face-to-face 2D/2D Schottky heterojunction interface are the major contributors to the excellent hydrogen evolution performance of the composite photocatalyst.展开更多
Rapid industrialization has accordingly increased the demand for energy.This has resulted in the increasingly severe energy and environmental crises.Hydrogen production,based on the photocatalytic water splitting driv...Rapid industrialization has accordingly increased the demand for energy.This has resulted in the increasingly severe energy and environmental crises.Hydrogen production,based on the photocatalytic water splitting driven by sunlight,is able to directly convert solar energy into a usable or storable energy resource,which is considered to be an ideal alternative energy source to assist in solving the energy crisis and environmental pollution.Unfortunately,the hydrogen production efficiency of single phase photocatalysts is too low to meet the practical requirements.The construction of heterostructured photocatalyst systems,which are comprised of multiple components or multiple phases,is an efficient method to facilitate the separation of electron‐hole pairs to minimize the energy‐waste,provide more electrons,enhance their redox ability,and hence improve the photocatalytic activity.We summarize the recent progress in the rational design and fabrication of nanoheterostructured photocatalysts.The heterojunction photocatalytic hydrogen generation systems can be divided into type‐I,type‐II,pn‐junction and Z‐scheme junction,according to the differences in the transfer of the photogenerated electrons and holes.Finally,a summary and some of the challenges and prospects for the future development of heterojunction photocatalytic systems are discussed.展开更多
基金supported by the National Natural Science Foundation of China(U1705251,21871217,21573170,21433007)the National Key Research and Development Program of China(2018YFB1502001)~~
文摘Sunlight-driven photocatalytic water-splitting for hydrogen(H2)evolution is a desirable strategy to utilize solar energy.However,this strategy is restricted by insufficient light harvesting and high photogenerated electron-hole recombination rates of TiO2-based photocatalysts.Here,a graphene-modified WO3/TiO2 step-scheme heterojunction(S-scheme heterojunction)composite photocatalyst was fabricated by a facile one-step hydrothermal method.In the ternary composite,TiO2 and WO3 nanoparticles adhered closely to reduced graphene oxide(rGO)and formed a novel S-scheme heterojunction.Moreover,rGO in the composite not only supplied abundant adsorption and catalytically active sites as an ideal support but also promoted electron separation and transfer from the conduction band of TiO2 by forming a Schottky junction between TiO2 and rGO.The positive cooperative effect of the S-scheme heterojunction formed between WO3 and TiO2 and the Schottky heterojunction formed between TiO2 and graphene sheets suppressed the recombination of relatively useful electrons and holes.This effect also enhanced the light harvesting and promoted the reduction reaction at the active sites.Thus,the novel ternary WO3/TiO2/rGO composite demonstrated a remarkably enhanced photocatalytic H2 evolution rate of 245.8μmol g^-1 h^-1,which was approximately 3.5-fold that of pure TiO2.This work not only presents a low-cost graphene-based S-scheme heterojunction photocatalyst that was obtained via a feasible one-step hydrothermal approach to realize highly efficient H2 generation without using noble metals,but also provides new insights into the design of novel heterojunction photocatalysts.
基金supported by the National Natural Science Foundation of China(21421001,21276116,21477050,21301076,21303074)Natural Science Foundation of Jiangsu Province(BK20140530,BK20150482)+5 种基金China Postdoctoral Science Foundation(2015M570409)Chinese-German Cooperation Research Project(GZ1091)Program for High-Level Innovative and Entrepreneurial Talents in Jiangsu ProvinceProgram for New Century Excellent Talents in University(NCET-13-0835)Henry Fok Education Foundation(141068)Six Talents Peak Project in Jiangsu Province(XCL-025)~~
文摘With the significant discharge of antibiotic wastewater into the aquatic and terrestrial ecosystems, antibiotic pollution has become a serious problem and presents a hazardous risk to the environment. To address such issues, various investigations on the removal of antibiotics have been undertaken. Photocatalysis has received tremendous attention owing to its great potential in removing antibiotics from aqueous solutions via a green, economic, and effective process. However, such a technology employing traditional photocatalysts suffers from major drawbacks such as light absorption being restricted to the UV spectrum only and fast charge recombination. To overcome these issues, considerable effort has been directed towards the development of advanced visible light-driven photocatalysts. This mini review summarises recent research progress in the state-of-the-art design and fabrication of photocatalysts with visible-light response for photocatalytic degradation of antibiotic wastewater. Such design strategies involve the doping of metal and non-metal into ultraviolet light-driven photocatalysts, development of new semiconductor photocatalysts, construction of heterojunction photocatalysts, and fabrication of surface plasmon resonance-enhanced photocatalytic systems. Additionally, some perspectives on the challenges and future developments in the area of photocatalytic degradation of antibiotics are provided.
文摘Constructing step-scheme(S-scheme)heterojunctions has been confirmed as a promising strategy for enhancing the photocatalytic activity of composite materials.In this work,a series of sulfur-doped g-C3N4(SCN)/TiO2 S-scheme photocatalysts were synthesized using electrospinning and calcination methods.The as-prepared SCN/TiO2 composites showed superior photocatalytic performance than pure TiO2 and SCN in the photocatalytic degradation of Congo Red(CR)aqueous solution.The significant enhancement in photocatalytic activity benefited not only from the 1D well-distributed nanostructure,but also from the S-scheme heterojunction.Furthermore,the XPS analyses and DFT calculations demonstrated that electrons were transferred from SCN to TiO2 across the interface of the SCN/TiO2 composites.The built-in electric field,band edge bending,and Coulomb interaction synergistically facilitated the recombination of relatively useless electrons and holes in hybrid when the interface was irradiated by simulated solar light.Therefore,the remaining electrons and holes with higher reducibility and oxidizability endowed the composite with supreme redox ability.These results were adequately verified by radical trapping experiments,ESR tests,and in situ XPS analyses,suggesting that the electron immigration in the photocatalyst followed the S-scheme heterojunction mechanism.This work can enrich our knowledge of the design and fabrication of novel S-scheme heterojunction photocatalysts and provide a promising strategy for solving environmental pollution in the future.
基金financially supported by the Natural Science Basic Research Program of Shaanxi(Program No.2019JQ-841)Scientific Research Program Funded by Shaanxi Provincial Education Department(Program No.19JK0376)。
文摘Semiconductor heterojunction photocatalysts have received much concern due to their great application prospect in solar energy utilization and conversion.Rational construction of heterostructure with two or more semiconductor materials can integrate the advantages of multi-components to simultaneously improve the photo-induced charges separation,extend visible light absorption range and retain the high redox ability of photocatalysts.Recently,constructing of g-C3 N4-based heterostructure has become a hot focus due to the multiple merits of g-C3 N4,such as facile synthesis,high stability,unique optical and electronic characteristics.This review tries to give a comprehensive introduction and provide the possible tendency in design and fabrication of g-C3 N4-based heterojunction photocatalysts,especially in rational synthesis of type-II heterojunction,direct Z-scheme heterojunction,new type of S-scheme heterojunction,p-n heterojunction and Schottky heterojunction.Furthermore,the special charges transfer mechanisms of g-C3 N4-based heterojunctions are discussed and their potential applications in photocatalytic water splitting,photo-degradation of contaminants and photo-reduction of CO2 into fuels are also summarized.Finally,we attempt to propose some crucial issues based on the current research,which should be further investigated and resolved in this interesting research area.
基金the Deanship of Scientific Research(DSR)at King Abdulaziz University,Jeddah(No.RG-72–130–42)DSR for technical and financial support。
文摘Recently,a new opinion was put forward on general design standards for S-scheme heterojunction photocatalyst.Four types of S-scheme heterojunctions were analyzed.Specifically,the critical understanding on the curved Fermi level at the interface of S-scheme heterojunction is helpful to strengthen and promote the basic theory of photocatalysis.
基金the National Natural Science Foundation of China(Grant no.61875072)Joint Fund of Pre-research for the Ministry of Equipment and Education(Grant no.6141A02033409)+6 种基金International Cooperation and Exchange Project of Jilin Province(Grant no.20170414002GH)Science and Technology Project of Education Department of Jilin Province(Grant no.JJKH20190011KJ)Key Research Project of Frontier Science of CAS(Grant no.QYZDB-SSW-JSC031)Fund of Shanghai Natural Science Foundation(Grant nos.19XD1404100,18ZR1445900,19YF1454600,and 18ZR1445800)Open Fund of the State Key Laboratory of Integrated Optoelectronics(Grant no.IOSKL2019KF05)Special Grants from China Post-doctoral Science Foundation(pre-station)(Grant no.2019TQ0333)Fund of SITP Innovation Foundation(Grant no.CX-239,CX-292)for supporting this work.
文摘Organic-inorganic hybrid perovskite(OIHP)photodetectors that simultaneously achieve an ultrafast response and high sensitivity in the near-infrared(NIR)region are prerequisites for expanding current monitoring,imaging,and optical communication capbilities.Herein,we demonstrate photodetectors constructed by OIHP and an organic bulk heterojunction(BHJ)consisting of a low-bandgap nonfullerene and polymer,which achieve broadband response spectra up to 1μm with a highest external quantum efficiency of approximately 54%at 850 nm,an ultrafast response speed of 5.6 ns and a linear dynamic range(LDR)of 191 dB.High sensitivity,ultrafast speed and a large LDR are preeminent prerequisites for the practical application of photodetectors.Encouragingly,due to the high-dynamicrange imaging capacity,high-quality visible-NIR actual imaging is achieved by employing the OIHP photodetectors.We believe that state-of-the-art OIHP photodetectors can accelerate the translation of solution-processed photodetector applications from the laboratory to the imaging market.
文摘对B+注入的n on p平面结和分子束外延 (MBE)技术原位铟掺杂的n+ n p台面异质结的碲镉汞 (HgCdTe)长波光伏探测器暗电流进行了对比分析 .与n on p平面结器件相比 ,原位掺杂的n+ n p台面异质结器件得到较高的零偏动态阻抗 面积值 (R0 A) .通过与实验数据拟合 ,从理论上计算了这两种结构的器件在不同温度下的R0 A和在不同偏压下的暗电流 。
基金the National Natural Science Foundation of China(Nos.61605174 and 61774136)the Key Projects of Higher Education in Henan Province(No.17A140012)Research Grants Council,University Grants Committee(RGC,UGC)(GRF 152109/16E PolyU B-Q52T).
文摘The research of ultraviolet photodetectors(UV PDs)have been attracting extensive attention,due to their important applications in many areas.In this study,PtSe2/GaN heterojunction is in-situ fabricated by synthesis of large-area vertically standing two-dimensional(2D)PtSe2 film on n-GaN substrate.The PtSe2/GaN heterojunction device demonstrates excellent photoresponse properties under illumination by deep UV light of 265 nm at zero bias voltage.Further analysis reveals that a high responsivity of 193 mA·W^-1,an ultrahigh specific detectivity of 3.8 × 10^14 Jones,linear dynamic range of 155d B and current on/off ratio of^10^8,as well as fast response speeds of 45/102μs were obtained at zero bias voltage.Moreover,this device response quickly to the pulse laser of 266 nm with a rise time of 172 ns.Such high-performanee PtSe2/GaN heteroj u nction UV PD demonstrated in this work is far superior to previously reported results,suggesting that it has great potential for deep UV detection.
文摘The rapid recombination of photo-generated electron-hole pairs,insufficient active sites,and strong photocorrosion have considerably restricted the practical application of Cd S in photocatalytic fields.Herein,we designed and constructed a 2D/2D/2D layered heterojunction photocatalyst with cascaded 2D coupling interfaces.Experiments using electron spin resonance spectroscopy,ultraviolet photoelectron spectroscopy,and in-situ irradiation X-ray photoelectron spectroscopy were conducted to confirm the 2D layered CdS/WO_(3) step-scheme(S-scheme)heterojunctions and CdS/MX ohmic junctions.Impressively,it was found that the strong interfacial electric fields in the S-scheme heterojunction photocatalysts could effectively promote spatially directional charge separation and transport between CdS and WO_(3) nanosheets.In addition,2D Ti_(3)C_(2) MXene nanosheets with a smaller work function and excellent metal conductivity when used as a co-catalyst could build ohmic junctions with Cd S nanosheets,thus providing a greater number of electron transfer pathways and hydrogen evolution sites.Results showed that the highest visible-light hydrogen evolution rate of the optimized MX-Cd S/WO_(3) layered multi-heterostructures could reach as high as 27.5 mmol/g/h,which was 11.0 times higher than that of pure CdS nanosheets.Notably,the apparent quantum efficiency reached 12.0% at 450 nm.It is hoped that this study offers a reliable approach for developing multifunctional photocatalysts by integrating S-scheme and ohmic-junction built-in electric fields and rationally designing a 2D/2D interface for efficient light-to-hydrogen fuel production.
文摘The design and construction of heterojunction photocatalysts,which possess a staggered energy band structure and appropriate interfacial contact,is an effective way to achieve outstanding photocatalytic performance.In this study,2D/2D BiOBr/g‐C_(3)N_(4)heterojunctions were successfully obtained by a convenient in situ self‐assembly route.Under simulated sunlight irradiation,99%of RhB(10 mg·L–1,100 mL)was efficiently degraded by 1.5‐BiOBr/g‐C_(3)N_(4)within 30 min,which is better than the performance of both BiOBr and g‐C_(3)N_(4),and it has superior stability.In addition,the composite also exhibits enhanced photocatalytic activity for H2 production.The enhanced activity can be attributed to the intimate interface contact,the larger surface area,and the highly efficient separation of photoinduced electron–hole pairs.Based on the experimental results,a novel S‐scheme model was proposed to illuminate the transfer process of charge carriers.This study presents a simple way to develop novel step‐scheme photocatalysts for environmental and related applications.
基金supported by the National Key Basic Research Program of China(973)(2010CB934700)National Natural Science Foundation of China(21173015)+1 种基金Fundamental Research Funds for the Central Universities,China(YWF-11-03-Q-085)Innovation Foundation of BUAA for PhD Graduates,China~~
文摘Converting sustainable solar energy into hydrogen energy over semiconductor-based photocatalytic materials provides an alternative to fossil fuel consumption.However,efficient photocatalytic splitting of water to realize carbon-free hydrogen production remains a challenge.Heterojunction photocatalysts with well-defined dimensionality and perfectly matched interfaces are promising for achieving highly efficient solar-to-hydrogen conversion.Herein,we report the fabrication of a novel type of protonated graphitic carbon nitride(PCN)/Ti3C2 MXene heterojunctions with strong interfacial interactions.As expected,the two-dimensional(2D)PCN/2D Ti3C2 MXene interface heterojunction achieves a highly improved hydrogen evolution rate(2181μmol∙g‒1)in comparison with bulk g-C3N4(393μmol∙g‒1)and protonated g-C3N4(816μmol∙g‒1).The charge-regulated surfaces of PCN and the accelerated charge transport at the face-to-face 2D/2D Schottky heterojunction interface are the major contributors to the excellent hydrogen evolution performance of the composite photocatalyst.
基金supported by the National Natural Science Foundation of China (51572253,21271165)Scientific Research Grant of Hefei Science Center of CAS (2015SRG-HSC048)Cooperation between NSFC and Netherlands Organization for Scientific Research (51561135011)~~
文摘Rapid industrialization has accordingly increased the demand for energy.This has resulted in the increasingly severe energy and environmental crises.Hydrogen production,based on the photocatalytic water splitting driven by sunlight,is able to directly convert solar energy into a usable or storable energy resource,which is considered to be an ideal alternative energy source to assist in solving the energy crisis and environmental pollution.Unfortunately,the hydrogen production efficiency of single phase photocatalysts is too low to meet the practical requirements.The construction of heterostructured photocatalyst systems,which are comprised of multiple components or multiple phases,is an efficient method to facilitate the separation of electron‐hole pairs to minimize the energy‐waste,provide more electrons,enhance their redox ability,and hence improve the photocatalytic activity.We summarize the recent progress in the rational design and fabrication of nanoheterostructured photocatalysts.The heterojunction photocatalytic hydrogen generation systems can be divided into type‐I,type‐II,pn‐junction and Z‐scheme junction,according to the differences in the transfer of the photogenerated electrons and holes.Finally,a summary and some of the challenges and prospects for the future development of heterojunction photocatalytic systems are discussed.
