RuO₂ deposition on high entropy oxide support for electrochemical water oxidation in acidic medium

Developing efficient and durable electrocatalysts for the oxygen evolution reaction (OER) in acidic media remains a major challenge for proton exchange membrane water electrolysis. Herein, an equimolar high entropy oxide (HEO), (TiNbVMnCr)O_x, is synthesized and employed as a functional support for RuO₂ deposition through a simple impregnation process. The influence of the strong oxide support interaction is systematically investigated by comparing the (TiNbVMnCr)O_x HEO/carbon cloth (CC), TiO₂/CC, and bare CC substrates. Structural and morphological analyses reveal that the multicomponent HEO surface provides abundant nucleation sites, enabling uniform RuO₂ dispersion. Although RuO₂/TiO₂/CC exhibited slightly enhanced OER performance compared to the RuO₂/CC, the best performance was presented by applying the functional HEO interlayer in the RuO₂/HEO/CC. The optimized RuO₂/HEO/CC electrode delivers enhanced acidic OER activity, achieving a low overpotential of about 260 mV at 10 mA∙cm^-2. In addition, the catalyst exhibits excellent durability, maintaining stable performance for 48 h with minimal degradation. The improved performance is attributed to enhanced RuO₂ dispersion, strong interfacial coupling, and electronic modulation induced by the HEO interlayer.