Noble metal cocatalysts have shown great potential in boosting the performance of CdS in photocatalytic water splitting.However,the mechanism and kinetics of electron transfer in noble-metal-decorated CdS during pract...Noble metal cocatalysts have shown great potential in boosting the performance of CdS in photocatalytic water splitting.However,the mechanism and kinetics of electron transfer in noble-metal-decorated CdS during practical hydrogen evolution is not clearly elucidated.Herein,Pt-nanoparticle-decorated CdS nanorods(CdS/Pt)are utilized as the model system to analyze the electron transfer kinetics in CdS/Pt heterojunction.Through femtosecond transient absorption spectroscopy,three dominating exciton quenching pathways are observed and assigned to the trapping of photogenerated electrons at shallow states,recombination of free electrons and trapped holes,and radiative recombination of locally photogenerated electron-hole pairs.The introduction of Pt cocatalyst can release the electrons trapped at the shallow states and construct an ultrafast electron transfer tunnel at the CdS/Pt interface.When CdS/Pt is dispersed in acetonitrile,the lifetime and rate for interfacial electron transfer are respectively calculated to be~5.5 ps and~3.5×10^(10) s^(−1).The CdS/Pt is again dispersed in water to simulate photocatalytic water splitting.The lifetime of the interfacial electron transfer decreases to~5.1 ps and the electron transfer rate increases to~4.9×10^(10) s^(−1),confirming that Pt nanoparticles serve as the main active sites of hydrogen evolution.This work reveals the role of Pt cocatalysts in enhancing the photocatalytic performance of CdS from the perspective of electron transfer kinetics.展开更多
Chemical electron microscopy(CEM),a toolbox that comprises imaging and spectroscopy techniques,provides dynamic morphological,structural,chemical,and electronic information about an object in chemical environment unde...Chemical electron microscopy(CEM),a toolbox that comprises imaging and spectroscopy techniques,provides dynamic morphological,structural,chemical,and electronic information about an object in chemical environment under conditions of observable performance.CEM has experienced a revolutionary improvement in the past years and is becoming an effective characterization method for revealing the mechanism of chemical reactions,such as catalysis.Here,we mainly address the concept of CEM for heterogeneous catalysis in the gas phase and what CEM could uniquely contribute to catalysis,and illustrate what we can know better with CEM and the challenges and future development of CEM.展开更多
Semiconductor/metal junctions are widely discussed in photocatalysis.However,there is a notable scarcity of systematic studies focusing on photogenerated charge carrier transfer in such junctions.Herein,CdS/Pt,CdS/Au,...Semiconductor/metal junctions are widely discussed in photocatalysis.However,there is a notable scarcity of systematic studies focusing on photogenerated charge carrier transfer in such junctions.Herein,CdS/Pt,CdS/Au,and CdS/Ag are synthesized to serve as model systems for investigating the charge carrier transfer in semiconductor/metal junctions.Kelvin probe force microscopy is employed to visualize the transfer of photogenerated carriers in these materials.The results show that the electron transfer behavior under illumination is related to the conduction band position of CdS and the Fermi level position of the metal.Moreover,Schottky junctions hinder the transfer of photogenerated electrons from CdS to Pt and Au,whereas ohmic contacts facilitate the transfer of photogenerated electrons from CdS to Ag.This work provides novel insights into the mechanisms governing the transfer of photogenerated carriers in semiconductor/metal junctions.展开更多
文摘Noble metal cocatalysts have shown great potential in boosting the performance of CdS in photocatalytic water splitting.However,the mechanism and kinetics of electron transfer in noble-metal-decorated CdS during practical hydrogen evolution is not clearly elucidated.Herein,Pt-nanoparticle-decorated CdS nanorods(CdS/Pt)are utilized as the model system to analyze the electron transfer kinetics in CdS/Pt heterojunction.Through femtosecond transient absorption spectroscopy,three dominating exciton quenching pathways are observed and assigned to the trapping of photogenerated electrons at shallow states,recombination of free electrons and trapped holes,and radiative recombination of locally photogenerated electron-hole pairs.The introduction of Pt cocatalyst can release the electrons trapped at the shallow states and construct an ultrafast electron transfer tunnel at the CdS/Pt interface.When CdS/Pt is dispersed in acetonitrile,the lifetime and rate for interfacial electron transfer are respectively calculated to be~5.5 ps and~3.5×10^(10) s^(−1).The CdS/Pt is again dispersed in water to simulate photocatalytic water splitting.The lifetime of the interfacial electron transfer decreases to~5.1 ps and the electron transfer rate increases to~4.9×10^(10) s^(−1),confirming that Pt nanoparticles serve as the main active sites of hydrogen evolution.This work reveals the role of Pt cocatalysts in enhancing the photocatalytic performance of CdS from the perspective of electron transfer kinetics.
基金the National Natural Science Foundation of China(Nos.52161145403,22072164,51932005,22072090,21872163,and 22002173)Liao Ning Revitalization Talents Program(XLYC1807175)+1 种基金the Research Fund of SYNL.X.L.acknowledges the support from National Key R&D Program of China(2021YFA1500300)Y.N.acknowledges the Postdoctoral Science Foundation of China(2020M680999).
文摘Chemical electron microscopy(CEM),a toolbox that comprises imaging and spectroscopy techniques,provides dynamic morphological,structural,chemical,and electronic information about an object in chemical environment under conditions of observable performance.CEM has experienced a revolutionary improvement in the past years and is becoming an effective characterization method for revealing the mechanism of chemical reactions,such as catalysis.Here,we mainly address the concept of CEM for heterogeneous catalysis in the gas phase and what CEM could uniquely contribute to catalysis,and illustrate what we can know better with CEM and the challenges and future development of CEM.
基金supported by the National Key Research and Development Program of China(No.2022YFB3803600)the National Natural Science Foundation of China(Nos.22238009,51932007,U1905215,52073223,22278324,52272290,52173065,and 22202187)+2 种基金the Natural Science Foundation of Hubei Province of China(No.2022CFA001)the National Postdoctoral Program for Innovative Talents(No.BX2021275)the Project funded by China Postdoctoral Science Foundation(No.2022M712957).
文摘Semiconductor/metal junctions are widely discussed in photocatalysis.However,there is a notable scarcity of systematic studies focusing on photogenerated charge carrier transfer in such junctions.Herein,CdS/Pt,CdS/Au,and CdS/Ag are synthesized to serve as model systems for investigating the charge carrier transfer in semiconductor/metal junctions.Kelvin probe force microscopy is employed to visualize the transfer of photogenerated carriers in these materials.The results show that the electron transfer behavior under illumination is related to the conduction band position of CdS and the Fermi level position of the metal.Moreover,Schottky junctions hinder the transfer of photogenerated electrons from CdS to Pt and Au,whereas ohmic contacts facilitate the transfer of photogenerated electrons from CdS to Ag.This work provides novel insights into the mechanisms governing the transfer of photogenerated carriers in semiconductor/metal junctions.
