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

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-Co3O4) 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-Co3O4. 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 Co3O4 and commercial RuO2 catalysts, C-Ru-Co3O4 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 RuO2 sharply decreases within 1 h. Notably, C-Ru-Co3O4 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-Co3O4, can be effectively driven by a solar panel, revealing its potential for converting solar energy into clean chemical energy.