title: Unravelling charge separation via surface built-in electric fields within single particulate photocatalysts.
abstract: Kelvin Probe Force Microscopy (KPFM) and spatially resolved surface photovoltage (SRSPV) techniques were employed to reveal built-in electric fields and surface photogenerated charge distribution on single particulate photocatalysts. The photogenerated holes and electrons spread over the whole surface of the particulate photocatalyst are imaged on n-type BiVO4and p-type Cu2O single particles, respectively. It is demonstrated that the built-in electric field in the surface Space Charge Region (SCR) dictates the charge separation/transfer processes and allows the drift of one kind of the photogenerated carriers to the surface, while holding another kind of the carriers in the bulk. The results emphasize the role of the SCR played in the unidirectional charge transport between the bulk and surface in the particulate photocatalyst, which may be the crucial reason for low solar energy conversion efficiency.
authors.affiliation: State Key Laboratory of Catalysis, iChEM, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian National Laboratory for Clean Energy, Zhongshan Road 457, Dalian 116023, China. ftfan@dicp.ac.cn canli@dicp.ac.cn.
authors.forename: Ruotian
authors.initials: R
authors.lastname: Chen
authors.forename: Jian
authors.initials: J
authors.lastname: Zhu
authors.forename: Hongyu
authors.initials: H
authors.lastname: An
authors.forename: Fengtao
authors.initials: F
authors.lastname: Fan
authors.forename: Can
authors.initials: C
authors.lastname: Li