Exploring efficient co-catalysts to accurately steer the charge separation of semiconductor photocatalysts is highly desired yet remains challenging.Here,we tackle the significant challenge by in situ growing the Bi_(...Exploring efficient co-catalysts to accurately steer the charge separation of semiconductor photocatalysts is highly desired yet remains challenging.Here,we tackle the significant challenge by in situ growing the Bi_(12)O_(17)C_(l2)photocatalyst onto two-dimensional(2D)Cl-terminated Ti_(3)C_(2)MXene to construct 2D/2D heterojunction of Bi_(12)O_(17)C_(l2)and Ti_(3)C_(2).Firstly,2D few-layered Ti_(3)C_(2)MXene with chlorine groups has been successfully syn-thesized by Lewis acidic etching strategy with subsequent ultrasonic exfoliation.The grafting of chlorine terminations on the surface of MXene serves as nucleating centers and growth platform,resulting in the formation of strong interfacial bonds(Bi-Cl-Ti)between Bi_(12)O_(17)C_(l2)and Ti_(3)C_(2).These strong bonds can facilitate the separation and transfer of photo-generated charge carriers between Bi_(12)O_(17)C_(l2)photocatalyst and Ti_(3)C_(2)cocatalyst.As expec-ted,the photocatalytic degradation rate of Bi_(12)O_(17)C_(l2)/Ti_(3)C_(2)hybrids is 9.7 times higher than that of bare Bi_(12)O_(17)C_(l2)nanosheets.This work not only exhibits a new design concept to effectively steer the charge separation for photocatalysis,but also gives a reference for constructing efficient MXene-based photocatalytic systems.展开更多
Electrochemical treatment is a popular and efficient method for improving the photoelectrochemical performance of water‐splitting photoelectrodes.In our previous study,the electrochemical activation of Mo‐doped BiVO...Electrochemical treatment is a popular and efficient method for improving the photoelectrochemical performance of water‐splitting photoelectrodes.In our previous study,the electrochemical activation of Mo‐doped BiVO_(4) electrodes was ascribed to the removal of MoO_(x) segregations,which are considered to be surface recombination centers for photoinduced electrons and holes.However,this proposed mechanism cannot explain why activated Mo‐doped BiVO_(4) electrodes gradually lose their activity when exposed to air.In this study,based on various characterizations,it is suggested that electrochemical treatment not only removes partial MoO_(x) segregations but also initiates the formation of H_(y)MoO_(x) surface defects,which provide charge transfer channels for photogenerated holes.The charge separation of the Mo‐doped BiVO_(4) electrode was significantly enhanced by these charge transfer channels.This study offers a new insight into the electrochemical activation of Mo‐doped BiVO_(4) photoanodes,and the new concept of surface charge transfer channels,a long overlooked factor,will be valuable for the development of other(photo)electrocatalytic systems.展开更多
We propose and investigate a novel metal/SiO_2/Si_3N_4/SiO_2/SiGe charge trapping flash memory structure（named as MONOS）, utilizing Si Ge as the buried channel. The fabricated memory device demonstrates excellent pr...We propose and investigate a novel metal/SiO_2/Si_3N_4/SiO_2/SiGe charge trapping flash memory structure（named as MONOS）, utilizing Si Ge as the buried channel. The fabricated memory device demonstrates excellent programerasable characteristics attributed to the fact that more carriers are generated by the smaller bandgap of Si Ge during program/erase operations. A flat-band voltage shift 2.8 V can be obtained by programming at ＋11 V for 100 us. Meanwhile, the memory device exhibits a large memory window of ~7.17 V under ±12 V sweeping voltage, and a negligible charge loss of 18% after 104 s＇ retention. In addition, the leakage current density is lower than 2.52 × 10^（-7） A·cm^（-2） below a gate breakdown voltage of 12.5 V. Investigation of leakage current-voltage indicates that the Schottky emission is the predominant conduction mechanisms for leakage current. These desirable characteristics are ascribed to the higher trap density of the Si_3N_4 charge trapping layer and the better quality of the interface between the SiO_2 tunneling layer and the Si Ge buried channel. Therefore, the application of the Si Ge buried channel is very promising to construct 3 D charge trapping NAND flash devices with improved operation characteristics.展开更多
A novel benzene-ring engineered 1D/2D WO_(3)/g-C_(3)N_(4)S-scheme photocatalyst(BCNW)was rationally de-signed and successfully synthesized by the electrostatic self-assembly method.Experimental and Density Functional ...A novel benzene-ring engineered 1D/2D WO_(3)/g-C_(3)N_(4)S-scheme photocatalyst(BCNW)was rationally de-signed and successfully synthesized by the electrostatic self-assembly method.Experimental and Density Functional Theory results reveal that the integration of molecular benzene-ring in the framework of g-C_(3)N_(4)can not only narrow its bandgap and accelerate charge separation by forming a mid-state at the top of its valence band but more importantly open up a new additional bridge for speeding up the interfacial S-scheme charge transfer in BCNW.Benefitting from those multiple positive effects of benzene-ring inte-gration,as expected,BCNW S-scheme photocatalysts show superior photocatalytic H_(2)-production activity and reach 2971μmol h^(-1)g^(-1)under visible-light illumination,which is 3.35 times WO_(3)/g-C_(3)N_(4)S-scheme photocatalyst without benzene-ring integration.This work supplies an innovative strategy for the design of a high-efficiency S-scheme photocatalytic system by constructing a facile and additional molecular charge transfer channel at the interface.展开更多
As a versatile energy carrier,H_(2) is considered as one of the most promising sources of clean energy to tackle the current energy crisis and environmental concerns,which can be produced from photocatalytic water spl...As a versatile energy carrier,H_(2) is considered as one of the most promising sources of clean energy to tackle the current energy crisis and environmental concerns,which can be produced from photocatalytic water splitting.However,solar-driven photocatalytic H_(2) production from pure water in the absence of sacrificial reagents remains a great challenge.Herein,we demonstrate that the incorporation of Ru single atoms(SAs)into ZnIn_(2)S_(4)(Ru-ZIS)can enhance the light absorption,reduce the energy barriers for water dissociation,and construct a channel(Ru-S)for separating photogenerated electron−hole pairs,as a result of a significantly enhanced photocatalytic water splitting process.Impressively,the productivity of H_(2) reaches 735.2μmol g^(-1) h^(-1) under visible light irradiation in the absence of sacrificial agents.The apparent quantum efficiency(AQE)for H_(2) evolution reaches 7.5% at 420 nm,with a solarto-hydrogen(STH)efficiency of 0.58%,which is much higher than the value of natural synthetic plants(~0.10%).Moreover,Ru-ZIS exhibits steady productivity of H_(2) even after exposure to ambient conditions for 330 days.This work provides a unique strategy for constructing charge transfer channels to promote the separation of photogenerated electron−hole pairs,which may motivate the fundamental researches on catalyst design for photocatalysis and beyond.展开更多
Photocatalytic water oxidation is a crucial step in water splitting,but is generally restricted by the slow kinetics.Therefore,it is necessary to develop high-performance water oxidation photocatalysts.Herein,the Fe-d...Photocatalytic water oxidation is a crucial step in water splitting,but is generally restricted by the slow kinetics.Therefore,it is necessary to develop high-performance water oxidation photocatalysts.Herein,the Fe-doped Bi2WO6 nanosheets with oxygen vacancies(OVs)were synthesized for enhanced photocatalytic water oxidation efficiency,showing a synergistic effect between Fe dopants and OVs.When a molar fraction of 2%Fe was doped into the Bi2WO6 nanosheets,the visible-light-driven photocatalytic oxygen evolution rate was increased up to 131.3μmol·h^(-1)·g_(cat)^(-1)under ambient conditions,which was more than 3 times that of pure Bi2WO6 nanosheets.The proper doping concentration of Fe could promote the formation of OVs and at the same time modulate the band structure of catalysts,especially the position of the valence band maximum(VBM),leading to effective visible-light absorption and enhanced oxidizing ability of photogenerated holes.With ameliorated localized electron distribution,fast charge transfer channel emerged between the OVs and adjacent metal atoms,which accelerated the charge carrier transfer and promoted the separation of photoexcited electrons and holes.This work provides feasible approaches for designing efficient two-dimensional semiconductor water oxidation photocatalysts that could utilize visible-light,which will make more use of solar energy.展开更多
The use of conjugated microporous polymers(CMPs)in photocatalytic CO_(2)reduction(CO_(2)RR),leveraging solar energy and water to generate carbon-based products,is attracting considerable attention.However,the amorphou...The use of conjugated microporous polymers(CMPs)in photocatalytic CO_(2)reduction(CO_(2)RR),leveraging solar energy and water to generate carbon-based products,is attracting considerable attention.However,the amorphous nature of most CMPs poses challenges for effective charge carrier separation,limiting their application in CO_(2)RR.In this study,we introduce an innovative approach utilizing donorπ-skeleton engineering to enhance skeleton coplanarity,thereby achieving highly crystalline CMPs.Advanced femtosecond transient absorption and temperature-dependent photoluminescence analyses reveal efficient exciton dissociation into free charge carriers that actively engage in surface reactions.Complementary theoretical calculations demonstrate that our highly crystalline CMP(Py-TDO)not only greatly improves the separation and transfer of photoexcited charge carriers but also introduces additional charge transport pathways via intermolecularπ-πstacking.Py-TDO exhibits outstanding photocatalytic CO_(2) reduction capabilities,achieving a remarkable CO generation rate of 223.97μmol g^(-1)h^(-1)without the addition of chemical scavengers.This work lays pioneering groundwork for the development of novel highly crystalline materials,advancing the field of solar-driven energy conversion.展开更多
基金financially supported by the Natural Science Foundation of Jiangsu Province (No. BK20211280)the National Natural Science Foundation of China (No. 21975129)
文摘Exploring efficient co-catalysts to accurately steer the charge separation of semiconductor photocatalysts is highly desired yet remains challenging.Here,we tackle the significant challenge by in situ growing the Bi_(12)O_(17)C_(l2)photocatalyst onto two-dimensional(2D)Cl-terminated Ti_(3)C_(2)MXene to construct 2D/2D heterojunction of Bi_(12)O_(17)C_(l2)and Ti_(3)C_(2).Firstly,2D few-layered Ti_(3)C_(2)MXene with chlorine groups has been successfully syn-thesized by Lewis acidic etching strategy with subsequent ultrasonic exfoliation.The grafting of chlorine terminations on the surface of MXene serves as nucleating centers and growth platform,resulting in the formation of strong interfacial bonds(Bi-Cl-Ti)between Bi_(12)O_(17)C_(l2)and Ti_(3)C_(2).These strong bonds can facilitate the separation and transfer of photo-generated charge carriers between Bi_(12)O_(17)C_(l2)photocatalyst and Ti_(3)C_(2)cocatalyst.As expec-ted,the photocatalytic degradation rate of Bi_(12)O_(17)C_(l2)/Ti_(3)C_(2)hybrids is 9.7 times higher than that of bare Bi_(12)O_(17)C_(l2)nanosheets.This work not only exhibits a new design concept to effectively steer the charge separation for photocatalysis,but also gives a reference for constructing efficient MXene-based photocatalytic systems.
文摘Electrochemical treatment is a popular and efficient method for improving the photoelectrochemical performance of water‐splitting photoelectrodes.In our previous study,the electrochemical activation of Mo‐doped BiVO_(4) electrodes was ascribed to the removal of MoO_(x) segregations,which are considered to be surface recombination centers for photoinduced electrons and holes.However,this proposed mechanism cannot explain why activated Mo‐doped BiVO_(4) electrodes gradually lose their activity when exposed to air.In this study,based on various characterizations,it is suggested that electrochemical treatment not only removes partial MoO_(x) segregations but also initiates the formation of H_(y)MoO_(x) surface defects,which provide charge transfer channels for photogenerated holes.The charge separation of the Mo‐doped BiVO_(4) electrode was significantly enhanced by these charge transfer channels.This study offers a new insight into the electrochemical activation of Mo‐doped BiVO_(4) photoanodes,and the new concept of surface charge transfer channels,a long overlooked factor,will be valuable for the development of other(photo)electrocatalytic systems.
基金Supported by the National Science and Technology Major Project of China under Grant No 2013ZX02303007the National Key Research and Development Program of China under Grant No 2016YFA0301701the Youth Innovation Promotion Association of the Chinese Academy of Sciences under Grant No 2016112
文摘We propose and investigate a novel metal/SiO_2/Si_3N_4/SiO_2/SiGe charge trapping flash memory structure（named as MONOS）, utilizing Si Ge as the buried channel. The fabricated memory device demonstrates excellent programerasable characteristics attributed to the fact that more carriers are generated by the smaller bandgap of Si Ge during program/erase operations. A flat-band voltage shift 2.8 V can be obtained by programming at ＋11 V for 100 us. Meanwhile, the memory device exhibits a large memory window of ~7.17 V under ±12 V sweeping voltage, and a negligible charge loss of 18% after 104 s＇ retention. In addition, the leakage current density is lower than 2.52 × 10^（-7） A·cm^（-2） below a gate breakdown voltage of 12.5 V. Investigation of leakage current-voltage indicates that the Schottky emission is the predominant conduction mechanisms for leakage current. These desirable characteristics are ascribed to the higher trap density of the Si_3N_4 charge trapping layer and the better quality of the interface between the SiO_2 tunneling layer and the Si Ge buried channel. Therefore, the application of the Si Ge buried channel is very promising to construct 3 D charge trapping NAND flash devices with improved operation characteristics.
基金This work was financially supported by National Natural Sci-ence Foundation(No.52000044)the Outstanding Youth Project of Guangdong Natural Science Foundation(No.2021B1515020051)+3 种基金the Natural Science Foundation of Guangdong Province(Nos.2021A1515012610,2019050001)Special Fund Project of Science and Technology Application in Guangdong(No.2017B020240002)National 111 project,Department of Science and Technology of Guangdong(Nos.2019JC01L203,2020B0909030004)Science and Technology Program of Guangzhou(No.202102010418).
文摘A novel benzene-ring engineered 1D/2D WO_(3)/g-C_(3)N_(4)S-scheme photocatalyst(BCNW)was rationally de-signed and successfully synthesized by the electrostatic self-assembly method.Experimental and Density Functional Theory results reveal that the integration of molecular benzene-ring in the framework of g-C_(3)N_(4)can not only narrow its bandgap and accelerate charge separation by forming a mid-state at the top of its valence band but more importantly open up a new additional bridge for speeding up the interfacial S-scheme charge transfer in BCNW.Benefitting from those multiple positive effects of benzene-ring inte-gration,as expected,BCNW S-scheme photocatalysts show superior photocatalytic H_(2)-production activity and reach 2971μmol h^(-1)g^(-1)under visible-light illumination,which is 3.35 times WO_(3)/g-C_(3)N_(4)S-scheme photocatalyst without benzene-ring integration.This work supplies an innovative strategy for the design of a high-efficiency S-scheme photocatalytic system by constructing a facile and additional molecular charge transfer channel at the interface.
基金financially supported by the National Key R&D Program of China(2020YFB1505802)the Ministry of Science and Technology(2017YFA0208200)+1 种基金the National Natural Science Foundation of China(22025108,U21A20327,and 22121001)the start-up funding from Xiamen University.
文摘As a versatile energy carrier,H_(2) is considered as one of the most promising sources of clean energy to tackle the current energy crisis and environmental concerns,which can be produced from photocatalytic water splitting.However,solar-driven photocatalytic H_(2) production from pure water in the absence of sacrificial reagents remains a great challenge.Herein,we demonstrate that the incorporation of Ru single atoms(SAs)into ZnIn_(2)S_(4)(Ru-ZIS)can enhance the light absorption,reduce the energy barriers for water dissociation,and construct a channel(Ru-S)for separating photogenerated electron−hole pairs,as a result of a significantly enhanced photocatalytic water splitting process.Impressively,the productivity of H_(2) reaches 735.2μmol g^(-1) h^(-1) under visible light irradiation in the absence of sacrificial agents.The apparent quantum efficiency(AQE)for H_(2) evolution reaches 7.5% at 420 nm,with a solarto-hydrogen(STH)efficiency of 0.58%,which is much higher than the value of natural synthetic plants(~0.10%).Moreover,Ru-ZIS exhibits steady productivity of H_(2) even after exposure to ambient conditions for 330 days.This work provides a unique strategy for constructing charge transfer channels to promote the separation of photogenerated electron−hole pairs,which may motivate the fundamental researches on catalyst design for photocatalysis and beyond.
基金This work was financially supported by the National Key R&D Program of China(No.2017YFA0207301)the National Natural Science Foundation of China(Nos.21622107,11621063,U1532265,and 21890750)+1 种基金the Youth Innovation Promotion Association CAS(No.2016392),the Key Research Program of Frontier Sciences(No.QYZDY-SSW-SLH011)the Major Program of Development Foundation of Hefei Center for Physical Science and Technology(No.2017FXZY003).
文摘Photocatalytic water oxidation is a crucial step in water splitting,but is generally restricted by the slow kinetics.Therefore,it is necessary to develop high-performance water oxidation photocatalysts.Herein,the Fe-doped Bi2WO6 nanosheets with oxygen vacancies(OVs)were synthesized for enhanced photocatalytic water oxidation efficiency,showing a synergistic effect between Fe dopants and OVs.When a molar fraction of 2%Fe was doped into the Bi2WO6 nanosheets,the visible-light-driven photocatalytic oxygen evolution rate was increased up to 131.3μmol·h^(-1)·g_(cat)^(-1)under ambient conditions,which was more than 3 times that of pure Bi2WO6 nanosheets.The proper doping concentration of Fe could promote the formation of OVs and at the same time modulate the band structure of catalysts,especially the position of the valence band maximum(VBM),leading to effective visible-light absorption and enhanced oxidizing ability of photogenerated holes.With ameliorated localized electron distribution,fast charge transfer channel emerged between the OVs and adjacent metal atoms,which accelerated the charge carrier transfer and promoted the separation of photoexcited electrons and holes.This work provides feasible approaches for designing efficient two-dimensional semiconductor water oxidation photocatalysts that could utilize visible-light,which will make more use of solar energy.
基金supported by the National Natural Science Foundation of China(Grant Nos.22379105 and 22102112)the Natural Science Foundation of Shanxi Province(Grant Nos.20210302123110)。
文摘The use of conjugated microporous polymers(CMPs)in photocatalytic CO_(2)reduction(CO_(2)RR),leveraging solar energy and water to generate carbon-based products,is attracting considerable attention.However,the amorphous nature of most CMPs poses challenges for effective charge carrier separation,limiting their application in CO_(2)RR.In this study,we introduce an innovative approach utilizing donorπ-skeleton engineering to enhance skeleton coplanarity,thereby achieving highly crystalline CMPs.Advanced femtosecond transient absorption and temperature-dependent photoluminescence analyses reveal efficient exciton dissociation into free charge carriers that actively engage in surface reactions.Complementary theoretical calculations demonstrate that our highly crystalline CMP(Py-TDO)not only greatly improves the separation and transfer of photoexcited charge carriers but also introduces additional charge transport pathways via intermolecularπ-πstacking.Py-TDO exhibits outstanding photocatalytic CO_(2) reduction capabilities,achieving a remarkable CO generation rate of 223.97μmol g^(-1)h^(-1)without the addition of chemical scavengers.This work lays pioneering groundwork for the development of novel highly crystalline materials,advancing the field of solar-driven energy conversion.
