RuO2 sub-nanocluster decorated Co3O4 as efficient and pH-universal oxygen evolution electrocatalyst

Developing cost-effective and highly efficient oxygen evolution reaction (OER) electrocatalysts that operate in both acidic and alkaline media is crucial for industrial electrocatalytic water splitting. However, achieving high performance under dual pH conditions remains a significant challenge. Herein, we report the synthesis of multi-sized RuO₂ sub-nanoclusters on Co₃O₄ nanoarrays via a facile method, which demonstrates exceptional OER activity in both acidic and alkaline environments. The optimized catalyst exhibits remarkably low overpotentials of 165 mV in 0.5 M H₂SO₄ and 223 mV in 1 M KOH at a current density of 10 mA cm⁻², respectively. Additionally, it exhibits outstanding stability, maintaining performance over a 10-h continuous operation, which is attributed to the robust structural stability of the dispersed RuO₂ sub-nanocluster morphology. Atomic-scale investigations reveal a layer-by-layer growth mechanism of Ru on the Co₃O₄ substrate, transitioning from single atoms to monolayer clusters and ultimately to sub-nanoclusters as Ru loading increases. This growth mechanism provides a rational strategy for the precise design and synthesis of advanced cluster-based catalysts. Density functional theory (DFT) calculations further elucidate the strong oxide-support interactions between RuO₂ clusters and the Co₃O₄ matrix, facilitating electron transfer from RuO₂ to Co₃O₄ and generating an electron-deficient region. This electronic modulation enhances –OH adsorption and accelerates OER kinetics. These findings underscore the potential of metal sub-nanoclusters for designing highly efficient and durable electrocatalysts for water electrolysis.