Interfacial Engineering and Structural Modulation of RuO ₂ ‐Based Catalysts for Highly Active and Durable Oxygen Evolution Reaction in Acidic Environment

Abstract Developing highly active and durable catalysts for the oxygen evolution reaction (OER) under acidic conditions is key to commercializing green hydrogen production via water splitting. Here, we fabricated a cobalt oxide (Co 3 O 4 )‐synergized nickel‐doped ruthenium oxide (Ni‐RuO 2 ) heterojunction on reduced graphene oxide (Co 3 O 4 /Ni‐RuO 2 /rGO) as an efficient and durable OER electrocatalyst in acidic electrolytes. The interface of Co 3 O 4 /Ni‐RuO 2 heterojunction and doping of Ni into RuO 2 , as well as their effect on electronic structure, were examined by advanced characterizations. With only 1.36 wt% RuO 2 , the Co 3 O 4 /Ni‐RuO 2 /rGO heterojunction revealed an ultra‐low overpotential of 195 and 305 mV at 10 and 100 mA cm −2 , respectively. Moreover, the catalyst's performance was well maintained after operating for 100 h at 500 mA cm −2 , suggesting great promise for practical applications. Density functional theory calculations and in situ Raman analysis indicate that both the heterojunction structure and Ni doping play crucial roles in enhancing the OER activity and durability. This study provides a promising avenue for developing cost‐effective electrocatalysts with superior activity and stability for advanced energy conversion.