A General Method to Probe Oxygen Evolution Intermediates at Operating Conditions

Reducing high overpotential for the oxygen evolution reaction (OER) is an important challenge for the utilization of clean and renewable energy resources. An obstacle that badly impedes the design of efficient OER catalysts is the weak understanding of the oxygen intermediates. Because of the aqueous reaction environment of OER, direct detection of oxygen intermediates is very challenging. Herein, we develop a general method for operando probing OER intermediates under real working conditions. We proved that the electrochemically generated oxygen intermediates of OER, e.g., OH*, are electrophiles, which could be probed by reaction with nucleophiles such as alcohol molecules. The exceptional generality of this method is demonstrated in different reaction mediums (alkaline and acid) and on various types of materials (oxides and hydroxides). The new insights of the surface chemistry on OER catalysts from the experimental approach will benefit the design of new catalysts to reduce the cost of hydrogen production.