Semiconductor-cocatalyst interfacial electron transfer has widely been considered as a fast step occurring on picosecond-microsecond timescale in photocatalytic reaction.However,the formed potential barriers severely ...Semiconductor-cocatalyst interfacial electron transfer has widely been considered as a fast step occurring on picosecond-microsecond timescale in photocatalytic reaction.However,the formed potential barriers severely slow this interfacial electronic process by thermionic emission.Although trap-assisted charge recombination can transfer electrons from semiconductor to cocatalyst and can even be evident under weak illumination,the parallel connection with thermionic emission makes the photocatalytic photon utilization encounter a minimum along the variation of light intensity.By this cognition,the light-intensity-dependent photocatalytic behaviors can be predicted by simulating the photoinduced semiconductor-cocatalyst interfacial electron transfer that mainly determines the reaction rate.We then propose a(photo)electrochemical method to evaluate the time constants for occurring this interfacial electronic process in actual photocatalytic reaction without relying on extremely high photon flux that is required to generate discernible optical signal in common instrumental methods based on ultrafast pulse laser.The evaluated decisecond-second timescale can accurately guide us to develop certain strategies to facilitate this rate-determining step to improve photon utilization.展开更多
A novel Sr2CulnO3S oxysulfide p-type semiconductor photocatalyst has been prepared by solid state reaction method and it exhibits intriguing visible light absorption properties with a bandgap of 2.3 eV. The p-type sem...A novel Sr2CulnO3S oxysulfide p-type semiconductor photocatalyst has been prepared by solid state reaction method and it exhibits intriguing visible light absorption properties with a bandgap of 2.3 eV. The p-type semiconductor character of the synthesized Sr2CuInO3 S was confirmed by Hall efficient measurement and Mott-Schottky plot analysis. First-principles density functional theory calculations （DFT） and electrochem ical measurements were performed to elucidate the electronic structure and the energy band locations. It was found that the as-synthesized Sr2CuInO3S photocatalyst has appreciate conduction and valence band positions for hydrogen and oxygen evolution, respectively. Photocat alytic hydrogen production experiments under a visible light irradiation （A〉420 nm） were carried out by loading different metal and metal-like cocatalysts on Sr2CuInO3S and Rh was found to be the best one among the tested ones.展开更多
SrTiO3 is a promising candidate photocatalyst for overall water splitting.Loading suitable cocatalysts,such as NiOx,the mixture of Ni and NiO,remarkably improve the photocatalytic activity.However,spatial locations an...SrTiO3 is a promising candidate photocatalyst for overall water splitting.Loading suitable cocatalysts,such as NiOx,the mixture of Ni and NiO,remarkably improve the photocatalytic activity.However,spatial locations and functions of components in NiOx/SrTiO3 are under debate.Here,using first-principles density functional theory(DFT)calculations,we investigate the initial growth of Nin(n=1–4)and(NiO)n(n=1,2 and 4)clusters on stoichiometric(100)surfaces of SrTiO3,and explore interfacial and electronic structures of composite photocatalysts.It is found that Nin clusters are easier to undergo aggregation on SrO-termination than on TiO2-termination.The adsorption of Nincluster on(100)surfaces elevates the Fermi level towards the conduction band,which may benefit the occurrence of hydrogen evolution reaction.The structural similarity between(NiO)n cluster and surface has an essential effect on the most stable adsorption configuration.For(NiO)n/SrTiO3 systems,the occupied states of(NiO)n cluster well overlap with those of(100)surfaces in the valence band maximum,which is in favor of the separation of photogenerated electrons and holes to SrTiO3 support and(NiO)n cluster,respectively.The detailed DFT analysis provides important insights into the growth of NiOx on surfaces of SrTiO3and presents an explanation on the different models of NiOx/SrTiO3 photocatalyst proposed by experimental groups.Our calculations build a basis for further investigations on the mechanism of photocatalytic water-splitting reaction in NiOx/SrTiO3composite system.展开更多
文摘Semiconductor-cocatalyst interfacial electron transfer has widely been considered as a fast step occurring on picosecond-microsecond timescale in photocatalytic reaction.However,the formed potential barriers severely slow this interfacial electronic process by thermionic emission.Although trap-assisted charge recombination can transfer electrons from semiconductor to cocatalyst and can even be evident under weak illumination,the parallel connection with thermionic emission makes the photocatalytic photon utilization encounter a minimum along the variation of light intensity.By this cognition,the light-intensity-dependent photocatalytic behaviors can be predicted by simulating the photoinduced semiconductor-cocatalyst interfacial electron transfer that mainly determines the reaction rate.We then propose a(photo)electrochemical method to evaluate the time constants for occurring this interfacial electronic process in actual photocatalytic reaction without relying on extremely high photon flux that is required to generate discernible optical signal in common instrumental methods based on ultrafast pulse laser.The evaluated decisecond-second timescale can accurately guide us to develop certain strategies to facilitate this rate-determining step to improve photon utilization.
基金financially supported by the National Natural Science Foundation of China(Grant No.21090341 and 21361140346)the National Basic Research Program(973 Program)of the Ministry of Science and Technology of China(Grant No.2014CB239401)
文摘A novel Sr2CulnO3S oxysulfide p-type semiconductor photocatalyst has been prepared by solid state reaction method and it exhibits intriguing visible light absorption properties with a bandgap of 2.3 eV. The p-type semiconductor character of the synthesized Sr2CuInO3 S was confirmed by Hall efficient measurement and Mott-Schottky plot analysis. First-principles density functional theory calculations （DFT） and electrochem ical measurements were performed to elucidate the electronic structure and the energy band locations. It was found that the as-synthesized Sr2CuInO3S photocatalyst has appreciate conduction and valence band positions for hydrogen and oxygen evolution, respectively. Photocat alytic hydrogen production experiments under a visible light irradiation （A〉420 nm） were carried out by loading different metal and metal-like cocatalysts on Sr2CuInO3S and Rh was found to be the best one among the tested ones.
基金financially supported by the National Natural Science Foundation of China under Grant 21473183
文摘SrTiO3 is a promising candidate photocatalyst for overall water splitting.Loading suitable cocatalysts,such as NiOx,the mixture of Ni and NiO,remarkably improve the photocatalytic activity.However,spatial locations and functions of components in NiOx/SrTiO3 are under debate.Here,using first-principles density functional theory(DFT)calculations,we investigate the initial growth of Nin(n=1–4)and(NiO)n(n=1,2 and 4)clusters on stoichiometric(100)surfaces of SrTiO3,and explore interfacial and electronic structures of composite photocatalysts.It is found that Nin clusters are easier to undergo aggregation on SrO-termination than on TiO2-termination.The adsorption of Nincluster on(100)surfaces elevates the Fermi level towards the conduction band,which may benefit the occurrence of hydrogen evolution reaction.The structural similarity between(NiO)n cluster and surface has an essential effect on the most stable adsorption configuration.For(NiO)n/SrTiO3 systems,the occupied states of(NiO)n cluster well overlap with those of(100)surfaces in the valence band maximum,which is in favor of the separation of photogenerated electrons and holes to SrTiO3 support and(NiO)n cluster,respectively.The detailed DFT analysis provides important insights into the growth of NiOx on surfaces of SrTiO3and presents an explanation on the different models of NiOx/SrTiO3 photocatalyst proposed by experimental groups.Our calculations build a basis for further investigations on the mechanism of photocatalytic water-splitting reaction in NiOx/SrTiO3composite system.
