Surface orientation-dependent electro-oxidation of a polycrystalline gold electrode

The activity and stability of an electrocatalyst is governed by the structural and chemical changes occurring at the solid-liquid interface. While single crystal electrodes have often served as model systems to elucidate structure-function relationships, extending these insights to more realistic polycrystalline electrodes requires experimental techniques with spatial resolution that can operate under electrochemical conditions. Herein, the electro-oxidation of a polycrystalline gold electrode is investigated in situ using two-dimensional surface optical reflectance, electrochemical near ambient pressure X-ray photoelectron spectroscopy, and tomographic surface X-ray diffraction. This combination of techniques provides surface-sensitive chemical and structural information. In the case of the polycrystalline gold, a surface orientation-dependent oxidation behaviour is found where both the onset and growth of oxides/hydroxides are affected. Our approach provides an enhanced understanding of the dynamic behaviour of complex electrodes under harsh environments, enabling grain-resolved insight into electrochemical processes.