Hierarchical CoP@Ni2P catalysts for pH-universal hydrogen evolution at high current density

For large-scale implementation of electrochemical hydrogen production, it is essential to develop electrocatalysts that work well at high current densities over a wide pH range. Herein, we use a facile method to synthesize a hierarchical bimetal phosphide (CoP@Ni2P) on nickel foam, which requires very low overpotentials to achieve the benchmark 10 mA cm-2 (e.g., 16 mV in alkaline media). Furthermore, the CoP@Ni2P can deliver a high current density of 500 mA cm-2 at small overpotentials and show no obvious decay after the durability test for over 48 h at all pH levels. The outstanding catalytic performance is attributed to the superaerophobicity of the electrode surface, fast electron transport as well as the increased number of exposed active sites caused by the hierarchical structure and the synergistic effect of the heterostructures. Consequently, this work provides an advanced transition metal-based phosphide for large-scale hydrogen production in all pH ranges.