MOF-derived RuO ₂ /Co ₃ O ₄ heterojunctions as highly efficient bifunctional electrocatalysts for HER and OER in alkaline solutions

The oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) are key half reactions involved in electrochemical water splitting. The design of active and robust Co3O4-based electrocatalysts for overall water splitting in basic media is highly desirable but still remains a great challenge. Herein, a catalyst of a combined metal oxide heterojunction (RuO2/Co3O4) was synthesized by directly annealing a MOF-derived Co–Ru complex under an air atmosphere. The catalyst shows a low OER and HER overpotential of only 305 mV and 89 mV at 10 mA cm−2 in 1 M KOH solution, respectively. It contains only a small amount of precious metal oxides, however, and demonstrates a better performance than most of the other Co3O4-based electrocatalysts reported at the present stage.