In Situ FTIR Spectroscopy: Probing the Electrochemical Interface during the Oxygen Reduction Reaction on a Commercial Platinum High‐Surface‐Area Catalyst

Abstract

Abstract In situ observation of anion adsorption on industrial high‐surface‐area catalysts is used for the first time under oxygen reduction reaction (ORR) conditions with a defined mass transport. For this purpose, a specially fabricated electrode is used for which the catalyst layer is spray‐coated on top of a structured Au contact layer and applied to our recently developed in situ attenuated total reflectance FTIR wall‐jet electrode. The designed interface allows us to track anion adsorption and measure the reaction rate simultaneously under mass controlled conditions. The observed absorption bands are caused by anion interaction with the active phase and also the carbon support. If we analyze the absorption band intensity of adsorbed anions as a function of the oxygen reduction reaction rate, the band intensity decreases with the onset of the ORR. This shows that ORR inhibition is a complex interplay between site blocking caused by anion adsorption and oxide formation.