Lab‐based electrochemical X‐ray photoelectron spectroscopy for in‐situ probing of redox processes at the electrified solid/liquid interface

 

Abstract

A profound understanding of the solid/liquid interface is central in electrochemistry and electrocatalysis, as the interfacial properties ultimately determine the electro-reactivity of a system. Although numerous electrochemical methods exist to characterize this interface under operating conditions, tools for the in-situ observation of the surface chemistry, that is, chemical composition and oxidation state, are still scarce, and currently exclusively available at synchrotron facilities. Here, we demonstrate the ability of laboratory-based near-ambient pressure X-ray photoelectron spectroscopy to track changes in oxidation states in-situ with respect to the applied potential. In this proof-of-principle study with polycrystalline gold (Au) as the best-studied electrochemical standard, we show that during the oxygen evolution reaction (OER), at high OER overpotentials, Au³⁺ governs the interfacial chemistry, while, at lower overpotentials, Au⁺ dominates.

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