Hydrogen peroxide(H_(2)O_(2))is extensively used in medical disinfection,water treatment,and environmental protection.To achieve the green synthesis of H_(2)O_(2),g-C_(3)N_(4)-based photocatalysis is an effective stra...Hydrogen peroxide(H_(2)O_(2))is extensively used in medical disinfection,water treatment,and environmental protection.To achieve the green synthesis of H_(2)O_(2),g-C_(3)N_(4)-based photocatalysis is an effective strategy and shows great potential.Nonetheless,single g-C_(3)N_(4)exhibits poor photocatalytic properties due to severe photogenerated charge recombination.To solve this challenge,this work enables F^(−)adsorption on the surface of g-C_(3)N_(4)nanotubes in solution driven by Coulomb forces through pH adjustment and the addition of NH4F.The photocatalytic H_(2)O_(2)production rate of the optimal F^(−)-decorated g-C_(3)N_(4)is three times higher than that of pure g-C_(3)N_(4),attributing to the synergistic effect of F^(−)and H^(+).Quenching experiments verify that the photocatalytic H_(2)O_(2)production process of CNF is a two-electron oxygen reduction process.Electron quenching dynamics of g-C_(3)N_(4)and CNF are revealed by femtosecond transient absorption spectroscopy(fs-TAS).Compared to pure g-C_(3)N_(4),CNF has an additional ultrashort lifetime(3.1 ps)representing the interfacial electron transfer from the conduction band of g-C_(3)N_(4)to F^(−).In situ fs-TAS results show that the interfacial electron transfer rate and electron utilization efficiency are respectively increased from 1.5×10^(8)s^(–1)and 19%in air to 5.0×10^(8)s^(-1)and 45%in O_(2) atmosphere with ethanol sacrificial agent.Hence,the O_(2),H^(+),and photogenerated electrons are key substances in the H_(2)O_(2)evolution.This work has elucidated the dynamics mechanism of enhanced photocatalytic performance of F^(−)-modified g-C_(3)N_(4)and provides inspiration for the design and synthesis of efficient g-C_(3)N_(4)-based photocatalysts.展开更多
Photosynthesis is a promising method for H_(2)O_(2)production,but its application in pure water is limited by slow oxidation kinetics and rapid photocarrier recombination of photocatalysts.Herein,a novel defective car...Photosynthesis is a promising method for H_(2)O_(2)production,but its application in pure water is limited by slow oxidation kinetics and rapid photocarrier recombination of photocatalysts.Herein,a novel defective carbon nitride photocatalyst(D-C3-xN4)containing the C vacancies and the frustrated Lewis pairs(B and N of cyano group)is designed for H_(2)O_(2)photosynthesis,and the role of C vacancies on the electron transfer mechanism during photocatalysis is systematically investigated.The D-C_(3-x)N_(4) exhibits a H_(2)O_(2)production rate of 140.1μmol·g^(-1)·h^(-1) in pure water,which is 87.6 times that of C_(3)N_(4).Such superior performance for H_(2)O_(2)photosynthesis is found to arise from the C vacancies and frustrated Lewis pairs(FLPs).The C vacancies have strong electron-trapping ability,which greatly enhances the separation of photocarriers.The C vacancies can also effectively reduce O_(2)to*OOH via a proton-coupled process,which significantly accelerates the O_(2)reduction kinetics.Meanwhile,the FLPs show an outstanding catalytic activity for H_(2)O oxidation.This study not only provides a new structure for highly active photocatalysts,but also deepens the understanding of the electron transfer mechanism of photocatalysts with trapped sites.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.U23A20102,52202375,22469001,22261142666,and 22366028)the Natural Science Foundation of Hubei Province of China(No.2022CFA001)。
文摘Hydrogen peroxide(H_(2)O_(2))is extensively used in medical disinfection,water treatment,and environmental protection.To achieve the green synthesis of H_(2)O_(2),g-C_(3)N_(4)-based photocatalysis is an effective strategy and shows great potential.Nonetheless,single g-C_(3)N_(4)exhibits poor photocatalytic properties due to severe photogenerated charge recombination.To solve this challenge,this work enables F^(−)adsorption on the surface of g-C_(3)N_(4)nanotubes in solution driven by Coulomb forces through pH adjustment and the addition of NH4F.The photocatalytic H_(2)O_(2)production rate of the optimal F^(−)-decorated g-C_(3)N_(4)is three times higher than that of pure g-C_(3)N_(4),attributing to the synergistic effect of F^(−)and H^(+).Quenching experiments verify that the photocatalytic H_(2)O_(2)production process of CNF is a two-electron oxygen reduction process.Electron quenching dynamics of g-C_(3)N_(4)and CNF are revealed by femtosecond transient absorption spectroscopy(fs-TAS).Compared to pure g-C_(3)N_(4),CNF has an additional ultrashort lifetime(3.1 ps)representing the interfacial electron transfer from the conduction band of g-C_(3)N_(4)to F^(−).In situ fs-TAS results show that the interfacial electron transfer rate and electron utilization efficiency are respectively increased from 1.5×10^(8)s^(–1)and 19%in air to 5.0×10^(8)s^(-1)and 45%in O_(2) atmosphere with ethanol sacrificial agent.Hence,the O_(2),H^(+),and photogenerated electrons are key substances in the H_(2)O_(2)evolution.This work has elucidated the dynamics mechanism of enhanced photocatalytic performance of F^(−)-modified g-C_(3)N_(4)and provides inspiration for the design and synthesis of efficient g-C_(3)N_(4)-based photocatalysts.
基金supported by the Shaanxi Sanqin Scholars Innovation Team,the Science and Technology Project of Yan’an City(No.2023-CYL-193)the Key Science Research Plan of Department of Education in Shaanxi Province(No.23JS070)the Science Research Training Project(No.CLXZ2207).
文摘Photosynthesis is a promising method for H_(2)O_(2)production,but its application in pure water is limited by slow oxidation kinetics and rapid photocarrier recombination of photocatalysts.Herein,a novel defective carbon nitride photocatalyst(D-C3-xN4)containing the C vacancies and the frustrated Lewis pairs(B and N of cyano group)is designed for H_(2)O_(2)photosynthesis,and the role of C vacancies on the electron transfer mechanism during photocatalysis is systematically investigated.The D-C_(3-x)N_(4) exhibits a H_(2)O_(2)production rate of 140.1μmol·g^(-1)·h^(-1) in pure water,which is 87.6 times that of C_(3)N_(4).Such superior performance for H_(2)O_(2)photosynthesis is found to arise from the C vacancies and frustrated Lewis pairs(FLPs).The C vacancies have strong electron-trapping ability,which greatly enhances the separation of photocarriers.The C vacancies can also effectively reduce O_(2)to*OOH via a proton-coupled process,which significantly accelerates the O_(2)reduction kinetics.Meanwhile,the FLPs show an outstanding catalytic activity for H_(2)O oxidation.This study not only provides a new structure for highly active photocatalysts,but also deepens the understanding of the electron transfer mechanism of photocatalysts with trapped sites.
