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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.

Driven by the intensified demand for energy storage systems with high-energy density and safety, all-solid-state zinc (Zn) air batteries have drawn extensive attentions. However, the development of non-precious metals with high catalytic activity as the air electrode is still a big challenge. In this work, we realize the large-scale fabrication of single-crystal CoO nanorods with high active facets and abundant oxygen vacancies in-situ on conductive substrate, which exhibits superior electrocatalytic activity in both oxygen reduction reaction and oxygen evolution reaction. The all-solid-state Zn-air batteries assembled with such free-standing CoO NRs show low charge/discharge overpotentials, a high energy density and a high cyclic stability. Our work indicates that the rational structure design of catalysts can pave a new route to next generation efficient and durable electrochemical devices.