Interface Sensitivity in Electron/Ion Yield X-ray Absorption Spectroscopy: The TiO2-H2O Interface

Van Spronsen, M.A. and Zhao, X. and Jaugstetter, M. and Escudero, C. and Duchoň, T. and Hunt, A. and Waluyo, I. and Yang, P. and Tschulik, K. and Salmeron, M.B.

Volume: 12 Pages: 10212-10217
DOI: 10.1021/acs.jpclett.1c02115
Published: 2021

To understand corrosion, energy storage, (electro)catalysis, etc., obtaining chemical information on the solid-liquid interface is crucial but remains extremely challenging. Here, X-ray absorption spectroscopy (XAS) is used to study the solid-liquid interface between TiO2 and H2O. A thin film (6.7 nm) of TiO2 is deposited on an X-ray-transparent SiNx window, acting as the working electrode in a three-electrode flow cell. The spectra are collected based on the electron emission resulting from the decay of the X-ray-induced core-hole-excited atoms, which we show is sensitive to the solid-liquid interface within a few nm. The drain currents measured at the working and counter electrodes are identical but of opposite sign. With this method, we found that the water layer next to anatase is spectroscopically similar to ice. This result highlights the potential of electron-yield XAS to obtain chemical and structural information with a high sensitivity for the species at the electrode-electrolyte interface. © 2021 The Authors. Published by American Chemical Society.

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