We present our measurements of the oxygen electro-adsorption kinetics on IrO2 and RuO2 surfaces and their implications for our oxygen evolution reaction (OER) understanding. The slow kinetics of the OER is currently the largest source of inefficiency in water-splitting devices. The common picture is that the slow OER kinetics is a reflection of the OER’s multi-electron nature; as the OER takes place, the catalyst must stabilize a series of proton and electron transfer events via surface electro-adsorption. We present our measurements of the kinetics of these electro-adsorption events, specifically the deprotonation of H2O* to OH* and OH* to O*, two of the elementary steps of the OER. Our approach uses rate-dependent cyclic voltammetry to isolate the electro-adsorption rate constants from the electrochemical driving force. We further vary the electrolytes to examine how the rate constant varies with pH to reveal the nature of the proton and electron transfers on IrO2 and RuO2. Our measurement provide insights into the electro-adsorption process on oxides and information on the kinetics of the elementary steps within the OER.

Oxygen electro-adsorption kinetics on well-defined oxide surfaces

2019 Fall National Meeting

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