Effect of Fe2O3 coating on ZnO nanowires in photoelectrochemical water splitting: A synchrotron x-ray spectroscopic and spectromicroscopic investigation

Y. R. Lu, Y. F. Wang, H. W. Chang, Y. C. Huang, J. L. Chen, C. L. Chen, Y. C. Lin, Y. G. Lin, W. F. Pong, T. Ohigashi, N. Kosugi, C. H. Kuo, W. C. Chou*, C. L. Dong*

*Corresponding author for this work

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Abstract

An array of ZnO/Fe2O3 core-shell nanowires (NW) for the highly efficient absorption of light and carrier collection is developed for use in photoelectrochemical (PEC) water-splitting. The oriented NW architecture favors physical matching, providing a direct electron conduction pathway and reducing the diffusion length of photogenerated holes. This work involves a combination of spectral imaging, spectromicroscopy and in situ x-ray absorption spectroscopy; spectra are obtained under operando conditions. Direct investigation of oriented nanowires using polarization-dependent x-ray spectromicroscopy enables the determination of the relationship between anisotropic electronic orbitals and charge carrier water-splitting efficiency. The results of O K-edge STXM demonstrated that the ZnO/Fe2O3 core-shell NW exhibits strong anisotropy and thus provides higher electron-hole transport efficiency than bare ZnO. In situ XAS revealed that interfacial charge transfer between Fe 3d and Zn 4p states enhances the photoelectrochemical reaction in the ZnO/Fe2O3 core-shell NW. The photogenerated electrons of Fe2O3 are transferred from Fe 3d states to the Zn 4p state under photoelectrochemical conditions.

Original languageEnglish
Article number110469
Number of pages7
JournalSolar Energy Materials and Solar Cells
Volume209
DOIs
StatePublished - 1 Jun 2020

Keywords

  • In situ x-ray absorption spectroscopy
  • PEC water splitting
  • Scanning transmission x-ray microscope

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    Lu, Y. R., Wang, Y. F., Chang, H. W., Huang, Y. C., Chen, J. L., Chen, C. L., Lin, Y. C., Lin, Y. G., Pong, W. F., Ohigashi, T., Kosugi, N., Kuo, C. H., Chou, W. C., & Dong, C. L. (2020). Effect of Fe2O3 coating on ZnO nanowires in photoelectrochemical water splitting: A synchrotron x-ray spectroscopic and spectromicroscopic investigation. Solar Energy Materials and Solar Cells, 209, [110469]. https://doi.org/10.1016/j.solmat.2020.110469