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Charge separation via asymmetric illumination in photocatalytic Cu2O particles

Nature Energy (2018) | Download Citation


Solar-driven photocatalytic reactions provide a potential route to sustainable fuels. These processes rely on the effective separation of photogenerated charges, and therefore understanding and exploring the driving force for charge separation is key to improving the photocatalytic performance. Here, using surface photovoltage microscopy, we demonstrate that the photogenerated charges can be separated effectively in a high-symmetry Cu2O photocatalyst particle by asymmetric light irradiation. The holes and electrons are transferred to the illuminated and shadow regions, respectively, of a single photocatalytic particle. Quantitative results show that the intrinsic difference between electron and hole mobilities enables a diffusion-controlled charge separation process, which is stronger than that caused by conventional built-in electric fields (40 mV versus 10 mV). Based on the findings, we assemble spatially separated redox co-catalysts on a single photocatalytic particle and, in doing so, enhance the performance for a model photocatalytic reaction by 300%. These findings highlight the driving force caused by charge mobility differences and the use of asymmetric light illumination for charge separation in photocatalysis.

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This work was supported by the National Natural Science Foundation of China (grant no. 21633015, 21773228), the National Key Basic Research Program of China (973 Program, grant no. 2014CB239403) and the Strategic Priority Research Program and Equipment Development Project of the Chinese Academy of Sciences, grant no. XDB17000000, YJKYYQ20170002.

Author information


  1. State Key Laboratory of Catalysis, Dalian National Laboratory for Clean Energy, The Collaborative Innovation Centre of Chemistry for Energy Materials (iChEM), Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China

    • Ruotian Chen
    • , Shan Pang
    • , Hongyu An
    • , Jian Zhu
    • , Sheng Ye
    • , Yuying Gao
    • , Fengtao Fan
    •  & Can Li
  2. University of Chinese Academy of Sciences, Beijing, China

    • Ruotian Chen
    • , Hongyu An
    •  & Yuying Gao


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R.C. conceived and conducted most of experiments, and analysed data; S.P. conducted the theoretical simulation; H.A. analysed the SPV data and conducted Raman measurements; J.Z. helped in the SPVM measurements; S.Y. helped in the activity measurements; Y.G. analysed KPFM data; F.F. conceived most of the experiments and analysed data. The manuscript was written by R.C. and F.F.; C.L. proposed the project, analysed data and revised the manuscript.

Competing interests

The authors declare no competing interests.

Corresponding authors

Correspondence to Fengtao Fan or Can Li.

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