Synthesis of polyoxometalates derived bifunctional catalyst towards efficient overall water splitting in neutral and alkaline medium

The development of efficient hydrogen evolution and oxygen evolution reactions bifunctional electrocatalyst for overall water splitting is highly desired but still a great challenge, especially under neutral condition. With the unique properties of polyoxometalate and MOFs materials as well as rich transition metal contents, herein we successfully synthesize a novel bi-phase structure of cobalt and molybdenum carbide coated with nitrogen-doped graphite (Co-Mo₂C@NC) which possesses excellent activity as water splitting electrocatalyst at neutral pH. This noble metal-free, bi-phase electrocatalyst exhibits Hydrogen Evolution Reaction (HER) and Oxygen Evolution Reaction (OER) overpotentials of 260 mV and 440 mV at 10 mA cm^-2, respectively. The two-electrode system using Co-Mo₂C@NC as both the anode and cathode drives 10 mA cm^-2 at a cell voltage of 1.83 V with a remarkable long-term stability. Besides, the Co-Mo₂C@NC also shows promising activity in alkaline condition that reaches 10 mA cm^-2 at a cell voltage of 1.66 V. This work paves a new avenue to the design of the unique, economic and promising non-noble metal electrode materials for practical applications in the electrochemical energy storage and conversion devices.