Photoinduced carrier dynamical processes dominate the optical excitation properties of photocatalysts and further determine the photocatalytic performance.In addition,as the electrons generally possess a faster transf...Photoinduced carrier dynamical processes dominate the optical excitation properties of photocatalysts and further determine the photocatalytic performance.In addition,as the electrons generally possess a faster transfer rate than holes,hole transfer and accumulation are critical,and they play the key efficiency-limiting step during the photocatalytic process.Therefore,a comprehensive understanding of the dynamics of photogenerated holes and their determining factors in the photocatalytic system is highly essential to rationalize the full catalytic mechanism and develop highly efficient photocatalysts,which have not yet been revealed.In this work,the photoinduced charge carrier dynamics in InP/ZnS quantum dots(QDs)capped with longchain L-typed ligands(oleylamine)and inorganic ligands(sulfide ion(S^(2-)))were explored.Time-resolved photoluminescence and femtosecond transient-absorption spectroscopy unambiguously confirmed the ultrafast hole transfer from the InP core to S^(2-)ligands.Moreover,by probing the bleach of vibrational stretching of the ligands with transient midinfrared absorption spectroscopy,the hole transfer time was determined to be 4.2 ps.The injected holes are long-lived at the S^(2-) ligands(>4.5 ns),and they can remove electrostatically attached surfactants to compensate for the spatial charge redistribution.Finally,compared with other inorganic ligands such as Cl^(-) and PO_(4)^(3-),S^(2-) balances the ionic radii and net charge to ensure the optimal condition for charge transfer.Such observation rationalizes the excellent photocatalytic H_(2) evolution(213.6μmol mg^(-1) within 10 h)in InP/ZnS QDs capped with S^(2-) compared with those capped with other ligands and elucidates the role of surface ligands in the photocatalytic activity of colloidal QDs.展开更多
基金supported by the National Natural Science Foundation of China(NSFC,22002123 and U1862111)Sichuan Science and Technology Program(2020YFH0118,2021JDGD0029 and 2021YFH0055)+6 种基金the Open Fund of State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation(PLN201802)the Independent Research Fund Denmark-Nature Sciences(DFF-FNU,DFF-7014-00302)the Independent Research Fund Denmark-Sapere Aude starting grant(7026-00037A)the Research Fund for International Young Scientists from NSFC(21950410515)Swedish Research Council VR Starting Grant(2017-05337)the financial support from China Scholarship Council(201806320345,201908440313,201706170017,and 201806460021)Support from Swedish Energy Agency。
文摘Photoinduced carrier dynamical processes dominate the optical excitation properties of photocatalysts and further determine the photocatalytic performance.In addition,as the electrons generally possess a faster transfer rate than holes,hole transfer and accumulation are critical,and they play the key efficiency-limiting step during the photocatalytic process.Therefore,a comprehensive understanding of the dynamics of photogenerated holes and their determining factors in the photocatalytic system is highly essential to rationalize the full catalytic mechanism and develop highly efficient photocatalysts,which have not yet been revealed.In this work,the photoinduced charge carrier dynamics in InP/ZnS quantum dots(QDs)capped with longchain L-typed ligands(oleylamine)and inorganic ligands(sulfide ion(S^(2-)))were explored.Time-resolved photoluminescence and femtosecond transient-absorption spectroscopy unambiguously confirmed the ultrafast hole transfer from the InP core to S^(2-)ligands.Moreover,by probing the bleach of vibrational stretching of the ligands with transient midinfrared absorption spectroscopy,the hole transfer time was determined to be 4.2 ps.The injected holes are long-lived at the S^(2-) ligands(>4.5 ns),and they can remove electrostatically attached surfactants to compensate for the spatial charge redistribution.Finally,compared with other inorganic ligands such as Cl^(-) and PO_(4)^(3-),S^(2-) balances the ionic radii and net charge to ensure the optimal condition for charge transfer.Such observation rationalizes the excellent photocatalytic H_(2) evolution(213.6μmol mg^(-1) within 10 h)in InP/ZnS QDs capped with S^(2-) compared with those capped with other ligands and elucidates the role of surface ligands in the photocatalytic activity of colloidal QDs.
