Lin Zhang, Han Gao, Lixia Yang, Jianan Xu, Zhaoyu Jin, Bin Cai, Min Zhou
The high-valent state of Ru not only enhances the oxygen evolution reaction (OER) activity of RuO 2 but also accelerates the dissolution of Ru. Although La doping alleviates this issue, the underlying mechanism remains unclear. Here, scanning electrochemical microscopy (SECM) was used to analyze RuO 2 and La-RuO 2 during the OER. The surface interrogation mode enables measurement of the active Ru valence state, site density, and catalytic kinetics, while the generation-collection mode allows simultaneous monitoring of both catalytic activity and dissolution kinetics. These findings highlight the critical role of the Ru valence state in balancing activity and stability, offering insights for the design of high-performance Ru-based catalysts.