Improved kinetics of OER on Ru-Pb binary electrocatalyst by decoupling proton-electron transfer

Abstract

The acidic oxygen evolution reaction (OER) is central to water electrolysis using proton-exchange membranes. However, even as benchmark catalysts in the acidic OER, Ru-based catalysts still suffer from sluggish kinetics owing to the scaling relationship that arises from the traditional concerted proton-electron transfer (CPET) process. Motivated by the knowledge that a charged surface may be favorable for accelerating the OER kinetics, we posited the incorporation of elements with pseudocapacitive properties into Ru-based catalysts. Herein, we report a RuPbOx electrocatalyst for efficient and stable water oxidation in acid with a low overpotential of 191 mV to reach 10 mA cm−2 and a low Tafel slope of 39 mV dec−1. The combination of electrochemical analysis, X-ray photoelectron spectroscopy, and in situ Raman spectroscopy demonstrated that the improved OER kinetics was associated with the formation of superoxide precursors on the strongly charged surface after Pb incorporation, indicating a non-concerted proton-electron transfer mechanism for the OER on RuPbOx.