Vacancy-engineered Ru-based CNT electrocatalysts for ampere-level water splitting in alkaline and anion-exchange membrane water electrolyzers

Robust metal-support interactions are crucial for designing efficient and corrosion-resistant electrocatalysts, as they significantly enhance charge separation and catalytic activity while also improving the stability and atomic utilization of metal catalysts. Here, we reported a temperature-regulated synthesis strategy to fabricate a self-supporting Ru/B,N co-doped MoO 2 electrocatalyst on a CNT framework (RBNM/CNTs 500 ), designed to simultaneously enhance catalytic activity and durability under practical electrolyzer conditions. The RBNM/CNTs 500 featured a unique nanostructure with excellent conductivity and strong chemical stability, while oxygen-vacancy-rich MoO 2 units at the interface reinforced metal-support interactions. This architecture stabilized Ru species during the OER and facilitated proton transfer, thus accelerating HER kinetics as confirmed by density functional theory calculations. As a result, RBNM/CNTs 500 exhibited outstanding bifunctional electrocatalytic performance, achieving exceptionally low overpotentials of 9 mV for the HER and 166 mV for the OER at 10 mA cm ‒2 , along with superior overall water-splitting activity characterized by a low cell voltage of 1.42 V and stable ampere-level operation at 10, 1000, and 2000 mA cm ‒2 in alkaline media. When integrated into an anion-exchange membrane water electrolyzer, RBNM/CNTs 500 demonstrated exceptional durability and surpassed benchmark electrocatalysts in performance. This study offers mechanistic insights into defect engineering and underscores a rational design approach for next-generation energy conversion devices.