Branched heterostructures of nickel–copper phosphides as an efficient electrocatalyst for the hydrogen evolution reaction

Identifying highly efficient, abundant, cheap, Pt-free electrocatalysts for splitting water to produce hydrogen is critical to address the issues related to the fossil fuel consumption and environmental pollution. Nickel–copper phosphides have attracted interest as synergistic components with superior electrocatalytic activity for the hydrogen evolution reaction (HER). Herein, we report on branched heterostructures of nickel–copper phosphides (CuNi/P) grown on a 3D nickel foam (NF) substrate that were synthesized using a facile hydrothermal method and subsequent low-temperature phosphidization. These unique, branched heterostructures exhibited a strong synergetic effect between various metallic phosphides, and provided more active sites and improved the material’s electronic conductivity to produce a higher charge transfer rate. Consequently, the synthesized CuNi/P possessed superior electrocatalytic performance with a low overpotential of 99 mV at current density of 10 mA/cm2, and a low Tafel slope of 79 mV/decade for hydrogen evolution in alkaline solution. In addition, this electrocatalyst exhibited electrochemical resilience for at least 10 h, which was a good indication of its possible application for large-term water electrolysis. This reported strategy may provide a path for the development of other bimetallic phosphide materials with superior catalytic performance for the hydrogen evolution reaction.