High electrocatalytic hydrogen evolution activity on a coupled Ru and CoO hybrid electrocatalyst

Hydrogen evolution reaction (HER) is an essential step in converting renewable energy to clean hydrogen fuel. Exploring highly efficient, stable and cost-effective electrocatalysts is of crucial significance for sustainable HER. Here, we report the design of a coupled ruthenium/cobalt oxide (Ru/CoO) hybrid electrocatalyst for alkaline HER. In this hybrid metal/oxide system, the complicated alkaline HER pathways are overall facilitated; oxygen (O)-vacancy-abundant oxide enhances water splitting and Ru promotes successive hydrogen intermediates to generate hydrogen. The resulting Ru/CoO hybrid electrocatalyst exhibits significantly promoted catalytic activity compared with benchmark Ru catalyst, displaying an overpotential of 55 mV to generate a HER current density of 10 mA cm⁻², comparable with the state-of-the-art Pt/C catalyst and the most efficient alkaline HER electrocatalysts. Furthermore, the strong interaction of Ru nanoparticles with oxide support and the in-situ growth of oxide support on conductive substrate guarantee the long-term stability of as-fabricated Ru/CoO hybrid electrocatalyst. This newly designed hybrid catalyst with abundant metal/oxide interfaces may pave a new pathway for exploring efficient and stable HER electrocatalysts.