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
Photogenerated charge separation is a challenging step in semiconductor-based photosynthesis.Though numerous efforts have been devoted to developing multi-component photocatalyst heterostructures for improving charge ...Photogenerated charge separation is a challenging step in semiconductor-based photosynthesis.Though numerous efforts have been devoted to developing multi-component photocatalyst heterostructures for improving charge separation efficiency,the short distance between electrons and holes-aggregated regions still leads to undesirable charge recombination.Herein,a facile and commercial in-situ synthesis method was designed to directly prepare a three-component Au–carbon–TiO_(2)photocatalyst from Ti_(3)C_(2)MXene,air,CO_(2),and HAuCl_(4),in which the carbon layer bridged Au and TiO_(2)nanoparticles for stable and efficient photocatalytic hydrogen production.Kelvin probe measurements and density functional theory(DFT)calculations demonstrated that a multi-interfacial charge transmission network was successfully constructed to achieve a directional and long-distance spatial charge separation/transfer channel between TiO_(2)and Au through carbon layer,desirably inhibiting the recombination of photogenerated charge carriers.The hydrogen production rate of the formed three-component Au/C–TiO_(2)(CTA)photocatalyst was demonstrated to be 27 times higher than that of Au–TiO_(2),which also surpassed many reported Ti_(3)C_(2)MXene-derived carbon–TiO_(2)photocatalysts.This work sheds light on the ingenious use of 2D MXene to form a well-behaved TiO_(2)-based photocatalytic system and helps to propose future design principles in accelerating charge transfer.展开更多
The effective separation ability of photogenerated carriers plays a crucial role in catalytic hydrogen production.Establishing a heterojunction structure is an effective means to overcome the limited carrier separatio...The effective separation ability of photogenerated carriers plays a crucial role in catalytic hydrogen production.Establishing a heterojunction structure is an effective means to overcome the limited carrier separation ability of some single catalysts.In this paper,Cu,graphdiyne(GDY)and NiCoMoO_(4)are successfully coupled to construct a composite photocatalyst NCY-15%.The addition of sheet GDY effectively prevents the aggregation of NiCoMoO_(4),increases the number of active sites,and enhances the light-trapping ability of the composite catalyst.The synergistic interaction of S-scheme heterojunction and Ohmic junction heterojunction between Cu,GDY and NiCoMoO_(4)provides a unique transfer pathway for electrons,facilitating the rapid separation of photogenerated carriers and accelerating electron transfer,while retaining electrons with strong reducing capacity to participate in hydrogen production,thereby increasing the hydrogen evolution rate.This provides a new way for the development of GDY based photocatalysts.展开更多
The separation efficiency of electrons and holes and the enhancement of the surface reductive reaction in the metal sulfide semiconductor photocatalysts are important factors in boosting photocatalytic H_(2)evolution ...The separation efficiency of electrons and holes and the enhancement of the surface reductive reaction in the metal sulfide semiconductor photocatalysts are important factors in boosting photocatalytic H_(2)evolution from water.The control of both interface morphology and the charge-carrier utilization of metal sulfide-based photocatalysts can effectively improve the separation efficiency of electrons and holes and increase the surface reaction active sites,which are considered to be effective methods to improve the photocatalytic activity of semiconductors.Here,the Ti_(3)C_(2)(Mxene)modified all-sulfide 2D/2D Sscheme heterojunction Ti_(3)C_(2)/Zn In_(2)S_(4)(ZIS)/CdS composite material was firstly synthesized by a two-step solvothermal method.The formation of all-sulfide S-scheme heterojunction improves the efficiency of electron-hole separation.The intimate 2D/2D van der Waals structure provides a strong interaction force and a large contact area to enhance charge transfer.The addition of 2D Ti_(3)C_(2)forms the accumulation layer,reducing the recombination of electrons and holes.Under the synergistic promotion,the highest hydrogen production of the prepared Ti_(3)C_(2)/ZIS/CdS composite photocatalyst could reach 8.93 mmol/h/g.This work not only enriches the photocatalytic systems through integrating the ohmic junction and the 2D/2D all-sulfide S-scheme heterojunction,but also provides a satisfactory design strategy for engineering interfacial morphology and charge-carrier utilization.展开更多
ZnO micro-prisms are prepared on the p-type and n-type Si substrates, separately. The Ⅰ-Ⅴ curves analysed by AFM show that the interface junctions between the ZnO micro-prisms and the p-type substrate and between th...ZnO micro-prisms are prepared on the p-type and n-type Si substrates, separately. The Ⅰ-Ⅴ curves analysed by AFM show that the interface junctions between the ZnO micro-prisms and the p-type substrate and between the ZnO micro-prisms and the n-type Si substrate exhibit p-n junction behaviour and ohmic contuct behuviour, respectively. The formation of the p-n heterojunction and ohmic contact is ascribed to the intrinsic n-type conduction of ZnO material. Better field emission performance （lower onset voltage and larger emission current） is observed from an individual ZnO micro-prism grown on the n-type Si substrate. It is suggested that the n-Si/n-ZnO interracial ohmic contact benefits the electron emission; while the p-Si/n-ZnO interface heterojunction deteriorates the electron emission.展开更多
Interface engineering can improve the charge separation efficiency and inhibit photocorrosion is an emerging direction of developing more efficient and cost-effective photocatalytic systems.Herein,we report the sulfur...Interface engineering can improve the charge separation efficiency and inhibit photocorrosion is an emerging direction of developing more efficient and cost-effective photocatalytic systems.Herein,we report the sulfur-confined intimate Cd S intergrown Cd(Cd S/Cd)Ohmic junction(peanut-chocolate-ball like)for high-efficient H2production with superior anti-photocorrosion ability,which was fabricated from in-situ photoreduction of CdS intergrown Cd2SO4(OH)2(CdS/Cd2SO4(OH)2)prepared through a facile space-controlled-solvothermal method.The ratios of CdS/Cd can be effectively controlled by tunning that of CdS/Cd2SO4(OH)2which were prepared by adjusting the volume of reaction liquid and the remaining space of the reactor.Experiments investigations and density functional theory(DFT)calculations reveal that the Cd S intergrown Cd Ohmic junction interfaces(with appropriate content Cd intergrown on Cd S(19.54 wt%))are beneficial in facilitating the transfer of photogenerated electrons by constructing an interfacial electric field and forming sulfur-confined structures for preventing the positive holes(h+)oxidize the Cd S.This contributes to a high photocatalytic H2production activity of 95.40μmol h-1(about 32.3 times higher than bare Cd S)and possesses outstanding photocatalytic stability over 205 h,much longer than most Cd S-based photocatalysts previously reported.The interface engineering design inspired by the structure of peanut-chocolate-ball can greatly promote the future development of catalytic systems for wider application.展开更多
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.
基金supported by the National Natural Science Foundation of China(No.21972171)the Fundamental Research Funds for the Central Universities,South-Central MinZu University(Nos.CZQ23037,CZY23018)+1 种基金the Hubei Provincial Natural Science Foundation,China(No.2021CFA022)the Innovation and Entrepreneurship Training Program Funded by South-Central Minzu University(No.S202310524033).
文摘Photogenerated charge separation is a challenging step in semiconductor-based photosynthesis.Though numerous efforts have been devoted to developing multi-component photocatalyst heterostructures for improving charge separation efficiency,the short distance between electrons and holes-aggregated regions still leads to undesirable charge recombination.Herein,a facile and commercial in-situ synthesis method was designed to directly prepare a three-component Au–carbon–TiO_(2)photocatalyst from Ti_(3)C_(2)MXene,air,CO_(2),and HAuCl_(4),in which the carbon layer bridged Au and TiO_(2)nanoparticles for stable and efficient photocatalytic hydrogen production.Kelvin probe measurements and density functional theory(DFT)calculations demonstrated that a multi-interfacial charge transmission network was successfully constructed to achieve a directional and long-distance spatial charge separation/transfer channel between TiO_(2)and Au through carbon layer,desirably inhibiting the recombination of photogenerated charge carriers.The hydrogen production rate of the formed three-component Au/C–TiO_(2)(CTA)photocatalyst was demonstrated to be 27 times higher than that of Au–TiO_(2),which also surpassed many reported Ti_(3)C_(2)MXene-derived carbon–TiO_(2)photocatalysts.This work sheds light on the ingenious use of 2D MXene to form a well-behaved TiO_(2)-based photocatalytic system and helps to propose future design principles in accelerating charge transfer.
基金supported by the Innovative Team for Transforming Waste Cooking Oil into Clean Energy and High Value-Added Chemicals(2022QCXTD03)Ningxia low-grade resource high value utilization and environmental chemical integration technology innovation team project,and Ningxia Natural Science Foundation of 2022(Outstanding Youth Project),Project number:2022AAC05034.
文摘The effective separation ability of photogenerated carriers plays a crucial role in catalytic hydrogen production.Establishing a heterojunction structure is an effective means to overcome the limited carrier separation ability of some single catalysts.In this paper,Cu,graphdiyne(GDY)and NiCoMoO_(4)are successfully coupled to construct a composite photocatalyst NCY-15%.The addition of sheet GDY effectively prevents the aggregation of NiCoMoO_(4),increases the number of active sites,and enhances the light-trapping ability of the composite catalyst.The synergistic interaction of S-scheme heterojunction and Ohmic junction heterojunction between Cu,GDY and NiCoMoO_(4)provides a unique transfer pathway for electrons,facilitating the rapid separation of photogenerated carriers and accelerating electron transfer,while retaining electrons with strong reducing capacity to participate in hydrogen production,thereby increasing the hydrogen evolution rate.This provides a new way for the development of GDY based photocatalysts.
基金financially supported by the National Natural Science Foundation of China(Nos.21975084 and 51672089)the Ding Ying Talent Project of South China Agricultural University for their support。
文摘The separation efficiency of electrons and holes and the enhancement of the surface reductive reaction in the metal sulfide semiconductor photocatalysts are important factors in boosting photocatalytic H_(2)evolution from water.The control of both interface morphology and the charge-carrier utilization of metal sulfide-based photocatalysts can effectively improve the separation efficiency of electrons and holes and increase the surface reaction active sites,which are considered to be effective methods to improve the photocatalytic activity of semiconductors.Here,the Ti_(3)C_(2)(Mxene)modified all-sulfide 2D/2D Sscheme heterojunction Ti_(3)C_(2)/Zn In_(2)S_(4)(ZIS)/CdS composite material was firstly synthesized by a two-step solvothermal method.The formation of all-sulfide S-scheme heterojunction improves the efficiency of electron-hole separation.The intimate 2D/2D van der Waals structure provides a strong interaction force and a large contact area to enhance charge transfer.The addition of 2D Ti_(3)C_(2)forms the accumulation layer,reducing the recombination of electrons and holes.Under the synergistic promotion,the highest hydrogen production of the prepared Ti_(3)C_(2)/ZIS/CdS composite photocatalyst could reach 8.93 mmol/h/g.This work not only enriches the photocatalytic systems through integrating the ohmic junction and the 2D/2D all-sulfide S-scheme heterojunction,but also provides a satisfactory design strategy for engineering interfacial morphology and charge-carrier utilization.
文摘ZnO micro-prisms are prepared on the p-type and n-type Si substrates, separately. The Ⅰ-Ⅴ curves analysed by AFM show that the interface junctions between the ZnO micro-prisms and the p-type substrate and between the ZnO micro-prisms and the n-type Si substrate exhibit p-n junction behaviour and ohmic contuct behuviour, respectively. The formation of the p-n heterojunction and ohmic contact is ascribed to the intrinsic n-type conduction of ZnO material. Better field emission performance （lower onset voltage and larger emission current） is observed from an individual ZnO micro-prism grown on the n-type Si substrate. It is suggested that the n-Si/n-ZnO interracial ohmic contact benefits the electron emission; while the p-Si/n-ZnO interface heterojunction deteriorates the electron emission.
基金supported by the National Natural Science Foundation of China(22162008,22162007)the Science and Technology Supporting Project of Guizhou Province([2022]208,[2021]480)the Basic Research Program of Science&Technology Department of Guizhou Province([2020]1Y055)。
文摘Interface engineering can improve the charge separation efficiency and inhibit photocorrosion is an emerging direction of developing more efficient and cost-effective photocatalytic systems.Herein,we report the sulfur-confined intimate Cd S intergrown Cd(Cd S/Cd)Ohmic junction(peanut-chocolate-ball like)for high-efficient H2production with superior anti-photocorrosion ability,which was fabricated from in-situ photoreduction of CdS intergrown Cd2SO4(OH)2(CdS/Cd2SO4(OH)2)prepared through a facile space-controlled-solvothermal method.The ratios of CdS/Cd can be effectively controlled by tunning that of CdS/Cd2SO4(OH)2which were prepared by adjusting the volume of reaction liquid and the remaining space of the reactor.Experiments investigations and density functional theory(DFT)calculations reveal that the Cd S intergrown Cd Ohmic junction interfaces(with appropriate content Cd intergrown on Cd S(19.54 wt%))are beneficial in facilitating the transfer of photogenerated electrons by constructing an interfacial electric field and forming sulfur-confined structures for preventing the positive holes(h+)oxidize the Cd S.This contributes to a high photocatalytic H2production activity of 95.40μmol h-1(about 32.3 times higher than bare Cd S)and possesses outstanding photocatalytic stability over 205 h,much longer than most Cd S-based photocatalysts previously reported.The interface engineering design inspired by the structure of peanut-chocolate-ball can greatly promote the future development of catalytic systems for wider application.
