One‐Step Synthesis of Carbon‐Protected Co3O4 Nanoparticles toward Long‐Term Water Oxidation in Acidic Media

The design and development of highly efficient and stable oxygen evolution reaction (OER) electrocatalysts in acid media are important for various renewable technologies. Herein, an advanced Co3O4 electrocatalyst supported on a mesoporous hydrophobic carbon paper (Co/29BC) is formed via a simple one‐step thermal decomposition of cobalt nitrate. Through this novel approach, the amorphous carbon layer resulting from the thermal decomposition of carbon‐containing species in the mesoporous layer provides enhanced electronic conduction and protection against corrosion to the Co3O4 nanoparticles. Equally important, the OER performance is found to be correlated with the morphology and surface composition of Co3O4. With optimized Co3+ active sites and oxygen vacancies at the metal oxide surface, the Co3O4 catalyst shows superior OER performance and durability in a proton exchange membrane (PEM) water electrolyzer, with a small overpotential (350 mV) at a constant current density of 10 mA cm−1 for over 50 h. Accordingly, this work provides new insights toward the design of high‐performance and highly stable OER electrocatalysts in corrosive acidic environments.