Bridged Ov–Ru–O–Co coordination induced by Co$^{2+δ}$ substitution in Co/RuO$_2$ catalysts for enhanced alkaline hydrogen and oxygen evolution reactions

Tailoring a highly active and stable alkaline electrocatalyst endowed with an ultra-low electron transfer energy barrier for hydrogen/oxygen evolution reactions (HER/OER) has remained elusive to date. Herein, a defect-rich nanoporous Co$^{2+d}$ -incorporated RuO$_2$ (Co/RuO$_2$) catalyst was proposed that offered low overpotential and good stability for alkaline HER/OER. Ov–Ru–O–Co coordination under the electron coupling constructed by slight anchoring of Co$^{2+d}$ at Ru$^{4+d}$ sites played a pivotal role in optimizing the reaction energy barrier of the intermediates. Theoretical calculations suggested that Ov–Ru–O–Co coordination effectively optimized the primary active site by modulating the electron structure and position of the d-band center. This refinement enhanced the adsorption/desorption of reactive species, facilitating the overall progression of the catalytic reactions. Consequently, the optimal Co/RuO$_2$-1/50 catalyst achieved an ultralow overpotential at 10 mA cm$^{−1}$ , an impressive Tafel slope for both HER (26 mV, 54 mV dec$^{−1}$ ) and OER (243 mV, 88 mV dec$^{−1}$ ) and an outstanding stability for over 100 h for OER. This work offers a practical roadmap for the development of noble metal-based electrocatalysts that exhibit high activity/stability for alkaline HER/OER.