Operando identification of the oxide path mechanism with different dual-active sites for acidic water oxidation

The microscopic reaction pathway plays a crucial role in determining the electrochemical performance. However, artificially manipulating the reaction pathway still faces considerable challenges. In this study, we focus on the classical acidic water oxidation based on RuO 2 catalysts, which currently face the issues of low activity and poor stability. As a proof-of-concept, we propose a strategy to create local structural symmetry but oxidation-state asymmetric Mn 4-δ -O-Ru 4+δ active sites by introducing Mn atoms into RuO 2 host, thereby switching the reaction pathway from traditional adsorbate evolution mechanism to oxide path mechanism. Through advanced operando synchrotron spectroscopies and density functional theory calculations, we demonstrate the synergistic effect of dual-active metal sites in asymmetric Mn 4-δ -O-Ru 4+δ microstructure in optimizing the adsorption energy and rate-determining step barrier via an oxide path mechanism. This study highlights the importance of engineering reaction pathways and provides an alternative strategy for promoting acidic water oxidation. Microscopic reaction pathways are crucial for electrochemical performance, but manipulating them remains challenging. Here, the authors report an approach that involves integrating Mn into RuO 2 catalysts to switch the reaction mechanism of the oxygen evolution reaction from a traditional single metal-site adsorbate evolution mechanism to a different dual-metal-site oxide path mechanism.