Structural Investigation of the Cu/W/Co-based Mixed Metal Oxide Electrocatalyst using X-ray absorption Spectroscopy.

26 October 2023, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


Mixed metal oxide is an attractive electrocatalyst class for efficient water splitting, yet the identification of real active sites and understanding of synergistic effects are still insufficient. Here, we applied in situ synchrotron-based X-ray absorption spectro-electrochemistry (XAS-EC) to explore the bifunctional mixed Co-Cu-W oxide interface under electrocatalytic conditions. Our investigation, including X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS), elucidated the dynamic structural transformations of Co, Cu, and W during the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Ex situ XAS measurements indicate the local chemistry of the focused metal centers. The subsequent XAS-EC XANES and EXAFS measurements shed light on the chemical and structural evolution of the Co-Cu-W oxide, in which Co and Cu actively participate in OER and HER while W plays a crucial role as structure stabilizer. This approach provides a valuable means of revealing the complex catalytic mechanism of significantly emerging mixed metal oxide electrocatalysts for advanced water splitting.


mixed metal oxide
real active species
X-ray absorption spectroscopy

Supplementary materials

Supplementary Information
The supplementary information contains supporting experimental data and detailed descriptions for EXAFS data fitting. Supplementary information on synthesis of mixed metal oxide and its characterization is shown in Section 1. Section 2 focuses on fabrication of working electrode and electrochemical measurements. Section 3 shows fitting parameters on Ex-situ and in-situ XAS measurements along fitting in Imaginary R and K space to represent the goodness of the fit.


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