Real-time Observation of the Solid-liquid Interface of Catalyst Electrode for Water Electrolysis using Hard and Soft X-ray Absorption Spectroscopy

Abstract Real-time observation by soft X-ray absorption spectroscopy was performed using a wavelength-dispersive method originally developed by our group. This method is applicable to the analysis of chemical reactions at the solid-liquid interface of Co oxide catalyst electrodes used in the oxygen evolution reaction of water electrolysis and enables the observation of the O K-edge. We also used operando hard X-ray absorption spectroscopy to focus on the Co K absorption edge and observed the chemical state of the catalyst surface in operando with the sample and cell in the same arrangement. The results of both observations suggest that the relationship between the formation of intermediate species during the reaction and the chemical state of the catalyst surface can be discussed.