title: Effects of surface modification on photocatalytic activity of CdS nanocrystals studied by photoluminescence spectroscopy.
abstract: The surface features of semiconductors play very important roles in photocatalytic processes but they are far from being well understood. In this work, we used CdS nanocrystals (NCs) as a model semiconductor photocatalyst to investigate the influence of surface features on photocatalytic activity. The effects of surface modification on the recombination behavior were studied by photoluminescence (PL) spectroscopy. The surface of CdS NCs was modified by tuning the surface S/Cd ratio or by co-loading with Pt and/or PdS co-catalysts. It was found that the surface modifications significantly affect the emission bands at ~540 nm due to shallow traps and ~650 nm assigned to S(2-) vacancies, and consequently the photocatalytic activities. Without co-catalysts loading, the excited carriers are readily transferred to the shallow traps, while they are readily transferred to the co-catalysts upon co-catalysts loading. These results demonstrate that the surface features are crucial to photocatalytic activity of the CdS NCs. The surface modification is helpful for the excited carriers to transfer to either the shallow trap states or co-catalysts, resulting in higher quantum efficiency of photocatalytic H(2) production.
authors.affiliation: State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian National Laboratory for Clean Energy, P.O. Box 110, Dalian, 116023, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Huang
authors.forename: Jinhui
authors.initials: J
authors.lastname: Yang
authors.forename: Xiuli
authors.initials: X
authors.lastname: Wang
authors.forename: Jingfeng
authors.initials: J
authors.lastname: Han
authors.forename: Hongxian
authors.initials: H
authors.lastname: Han
authors.forename: Can
authors.initials: C
authors.lastname: Li