Ultrasmall RuO2/CoFe2O4 nanoparticles with robust interfacial interactions for the enhanced acidic oxygen evolution reaction†

The acidic stability of RuO₂-based electrocatalysts remains a critical hurdle for proton exchange membrane electrolyzers due to ruthenium leaching. Here, we report an ultrasmall RuO₂/CoFe₂O₄ (RFC) catalyst with robust interfacial interactions, synthesized via an adsorption–pyrolysis method. The RFC catalyst demonstrates an exceptionally low overpotential of 191 mV and outstanding stability, retaining its performance for over 100 hours in 0.5 M H₂SO₄. Experimental analyses indicate that the robust interfacial interactions between RuO₂ and CoFe₂O₄ facilitate efficient charge transfer, significantly enhancing the performance of the oxygen evolution reaction (OER). After the stability test, XRD, Raman, and TEM characterization confirmed that the RFC catalyst maintains its crystal structure and morphology, indicating excellent durability. These findings highlight the potential of RFC catalysts for sustainable hydrogen production and provide a novel approach to the design of advanced electrocatalysts through strategic interfacial engineering, paving the way for improved stability and performance in acidic OER applications.