Co-Motif-Engineered RuO ₂ Nanosheets for Robust and Efficient Acidic Oxygen Evolution

The development of efficient and reliable acidic oxygen evolution reaction (OER) electrocatalysts represents a crucial step in the process of water electrolysis. RuO 2, a benchmark OER catalyst, suffers from limited large-scale applicability due to its tendency toward the less stable lattice oxygen mechanism (LOM). This work reports the synthesis of Co-doped RuO 2 nanosheets with a unique porous morphology composed of interconnected grains via a facile molten salt method. Co doping modulates the grain size, effectively increasing the specific surface area and introducing oxygen vacancies. These oxygen vacancies, coupled with the Co dopants, form Co–O(V) motifs that tune the electronic configuration of Ru. This structural engineering promotes a shift in the OER mechanism from the detrimental LOM pathway to the more efficient adsorbate evolution mechanism (AEM), significantly enhancing the stability of the RuO 2 matrix in acidic environments. The optimized Co 0.108 –RuO 2 catalyst exhibits a low overpotential of 214 mV at 10 mA cm –2 and remarkable stability over commercial RuO 2 and undoped counterparts, owing to the synergistic effect of the increased surface area, Co–O(V) motifs, and favored AEM pathway. This strategy of utilizing Co doping to engineer morphology, electronic structure, and reaction mechanism offers a promising avenue for developing high-performance OER electrocatalysts.