Carbon-Encapsulated Ru–Co₃O₄ Nanosheets as Electrocatalysts for Acidic Water Oxidation

Abstract

Developing stable and highly active electrocatalysts for the oxygen evolution reaction (OER) in acidic media holds significant importance for proton-exchange membrane water electrolysis. Here, we report a carbon-protected, low Ru-doped cobalt oxide nanosheet array electrode (C−Ru−Co 3 O 4 ) for acid OER. The doping of Ru adjusts the electronic structure, optimizing the adsorption of reaction intermediates. Additionally, amorphous carbon, derived from polydopamine, effectively inhibits the overoxidation of Ru−Co 3 O 4 . Furthermore, the sheetlike structure and strong interplay between the catalyst and support promote mass and charge transfer while extending the long-term durability. Compared to Co 3 O 4 and commercial RuO 2 catalysts, C−Ru−Co 3 O 4 catalyst exhibits enhanced OER performance and stability. The optimized catalyst shows an overpotential of 252 mV at 10 mA cm −2 and can operate continuously in acidic media for more than 30 h, while the activity of commercial RuO 2 sharply decreases within 1 h. Notably, C−Ru−Co 3 O 4 also exhibits good hydrogen evolution reaction (HER) activity, with an overpotential of 125 mV at 10 mA cm −2 . Furthermore, the acid water splitting electrolyzer, based on bifunctional C−Ru−Co 3 O 4 , can be effectively driven by a solar panel, revealing its potential for converting solar energy into clean chemical energy.