Enriched Electrophilic Oxygen Species on Ru Optimize Acidic Water Oxidation

Ruthenium oxide (RuO₂) is considered one of the most promising catalysts for replacing iridium oxide (IrO₂) in the acidic oxygen evolution reaction (OER). Nevertheless, the performance of RuO₂ remains unacceptable due to the dissolution of Ru and the lack of *OH in acidic environments. This paper reports a grain boundary (GB)-rich porous RuO₂ electrocatalyst for the efficient and stable acidic OER. The involvement of GB regulates the valence state of Ru and weakens the interaction between Ru and O, effectively facilitating *OH adsorption and *OOH formation. Notably, achieved a record-high catalytic activity (145 mV at 10 mA cm^-2) with a low Tafel slope (40.9 mV dec^-1) and a remarkable mass activity of 332 mA mg^-1 _Ru at 1.5 V versus reversible hydrogen electrode is achieved. Additionally, the porous RuO₂ exhibits superb stability with an ultra-low degradation rate of 26 µV h^-1 over a 50-day durability test. This study opens a viable pathway for the development of efficient and robust Ru-based acidic OER electrocatalysts.