Order-disorder engineering of RuO₂ nanosheets towards pH-universal oxygen evolution

Ru-based electrocatalysts are considered promising anode catalysts towards water electrolysis due to their impressive activity under acidic conditions. Yet, caused by the collapse of the local crystalline domains and concurrent leaching of Ru species during the OER process, durability against structural degradation remains poor. Herein, we present an order-disorder structure optimization strategy, based on RuO₂ nanosheets with well-defined amorphous-crystalline boundaries supported on carbon cloth (a/c-RuO₂/CC), to effectively catalyze water oxidation, especially in the case of an acidic medium. Specifically, the as-prepared a/c-RuO₂/CC sample has achieved a lower overpotential of 150 mV at 10 mA cm^-2, a smaller Tafel slope of 47 mV dec^-1, and a significantly higher durability with suppressed dissolution of Ru, with regard to its crystalline (c-RuO₂/CC) and amorphous (a-RuO₂/CC) counterparts. Computational simulations combined with experimental characterizations uncover that the construction of the structurally ordered-disordered boundary enables a weakened Ru-O covalency with regard to the ordered counterpart, which suppresses the leaching of active Ru species from the crystalline phase, thus enhances stability. An upshift of the d-band center in a/c-RuO₂/CC relative to a-RuO₂/CC reduces the energy barrier of the potential-determining step (*O → *OOH), thereby dramatically boosting activity.