RuO2/CeO2 heterostructure anchored on carbon spheres as a bifunctional electrocatalyst for efficient water splitting in acidic media

The use of proton exchange membrane (PEM) hydrolysis technology holds promise for eco-friendly hydrogen production using renewable energy sources. However, developing efficient, cost-effective, and durable bifunc-tional electrocatalysts for the acidic oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) remains challenging. Here, we synthesized RuO2/CeO2 heterojunction loaded on carbon spheres (RuO2/ CeO2@C) via hydrothermal and annealing techniques to address this issue. Our experiments demonstrate exceptional catalytic activity of RuO2/CeO2@C for both OER and HER, with overpotentials of 170 and 120 mV, respectively, at 10 mA/cm2 in 0.5 M H2SO4. Moreover, the electrocatalyst enables overall water splitting at 1.54 V and maintains stability for over 100 h at 10 mA/cm2. Density functional theory (DFT) calculations suggest that RuO2/CeO2 heterojunction modifies d-band center of Ru, balances H adsorption/desorption behavior, acceler-ates reaction kinetics, and lowers the energy barrier, thereby enhancing electrocatalytic activity. These findings provide valuable insights for future efficient bifunctional water splitting electrocatalyst design.