Operando tracking of oxidation-state changes by coupling electrochemistry with time-resolved X-ray absorption spectroscopy demonstrated for water oxidation by a cobalt-based catalyst film

• DOI: 10.1007/s00216-021-03515-0
• Publication Date: 2021-07-17T22:02:25Z
• Authors: Chiara Pasquini; Si Liu; Petko Chernev; Diego Gonzalez-Fl...; Mohammad Reza Moh...; Paul Kubella; Shan Jiang; Stefan Loos; Katharina Klingan; Vadim Sikolenko; Stefan Mebs; Michael Haumann; Paul Beyer; Luca D’Amario; Rodney D. L. Smith; Ivelina Zaharieva; Holger Dau
• Keywords: Oxygen evolution; Oxidation state; Catalytic Oxidation

Transition metal oxides are promising electrocatalysts for water oxidation, i.e., the oxygen evolution reaction (OER), which is critical in electrochemical production of non-fossil fuels. The involvement oxidation state changes OER electrocatalysis increasingly recognized literature. Tracing these states under operation conditions could provide relevant information performance optimization and development durable catalysts, but further methodical developments needed. Here, we propose a strategy to use single-energy X-ray absorption spectroscopy monitoring oxidation-state during with millisecond time resolution. procedure obtain time-resolved values, using two calibration curves, explained detail. We demonstrate significance this approach as well possible sources data misinterpretation. conclude that combination techniques allows us investigate kinetics redox transitions distinguish catalytic current from current. Tracking Co ions electrodeposited oxide films cyclic voltammetry neutral pH electrolyte serves proof principle.