Interface engineering of Co2N0.67/CoMoO4 heterostructure nanosheets as a highly active electrocatalyst for overall water splitting and Zn-H2O cell

The key in developing a low-cost, high-efficiency electrocatalyst for hydrogen generation is not only cutting the cost by avoiding noble metals but also utilizing the structure–function relationship to expose the maximum amounts of active sites on the surface by increasing the interface between the active components. Here, we demonstrated full-cycle synthesis, characterization, and optimization of Co2N0.67/CoMoO4 electrocatalyst on carbon-supported by density functional theory (DFT) calculations. The DFT calculation revealed a significant charge accumulation at the interface between Co2N0.67 and CoMoO4, suggesting the possibility of a strong synergy. As expected, electrochemical studies have shown a bifunctional Co2N0.67/CoMoO4 catalyst with low overpotential and durability towards hydrogen/oxygen evolution reactions (HER/OER) in alkaline electrolytes and robust overall water splitting performance at high current densities. In addition, the optimized Co2N0.67/CoMoO4 catalyst is also used in a Zn-H2O cell and displayed a power density exceeding Pt/C with the long-term stability of up to 170 h. The excellent electrochemical performance is the outcome of the better charge mobility at the interface resulted in the unique synergy between the active components.