Preparation of RuO₂/Co₃O₄@NC composite and its electrocatalytic performance for overall water splitting

The development of bifunction RuO₂-based electrocatalysts with high performance and stability is the key to complete water splitting for hydrogen production. RuO₂/Co₃O₄@NC composite was successfully prepared by coprecipitation, adsorption and calcination. The performance and long-term stability of the composite were studied by electrochemical testing. The test results show that the hydrogen evolution overpotential of RuO₂/Co₃O₄@NC electrode is only 53 mV when the current density is 10 mA·cm⁻², and it is continuously stable for 100 h at 10 mA·cm⁻² current density. At a current density of 10 mA·cm⁻², the overpotential of the oxygen evolution reaction of the RuO₂/Co₃O₄@NC electrode is 200 mV, and it is operated continuously and stably for 100 h at this current density. When RuO₂/Co₃O₄@NC is formed into an alkaline total decomposition hydrolysis cell, the voltage is only 1.40 V to reach the current density of 10 mA·cm⁻², which is significantly lower than that of 20% Pt/C||commercial RuO₂ electrolytic cell (1.61 V). The cell runs stably for 80 h at 10 mA·cm⁻². The results show that the heterostructure of RuO₂ and Co₃O₄ can effectively improve hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) performance. The surface of nitrogen-doped carbon shell can effectively improve the long-term HER and OER stability of the composite.