Self-supporting hierarchically micro/nano-porous Ni3P-Co2P-based film with high hydrophilicity for efficient hydrogen production

Designing efficient and stable non-precious metal HER (hydrogen evolution reaction) electrocatalysts with high large current density adaptability is significant for industrial application of hydrogen production by water electrolysis. Herein, a facile strategy was developed to construct a multi-phase Ni3P-Co2P-(Ni-Co) film with self-supporting hierarchically micro/nano-porous structure by using bubble template method electrodeposition of self-supporting micro-porous NiCoP film, oxygen-free annealing for phase separation producing Ni3P-Ni-Co2P-Co structure, and acid etching for constructing surface nano-porous structure. The effective active sites for HER was significantly increased due to the hierarchically micro/nano-porous structure, which not only enlarged the surface roughness, but enhanced the bubble detachment by improving the hydrophilicity. Meanwhile, the HER electrolysis durability was improved benefiting from the Ni3P-Co2P phases with high corrosion resistance (especially in acid solution) and the self-supporting film structure without binder. Consequently, the NiCoP-OA-AE film exhibited high HER catalytic performance, which delivered a current density of 10 mA cm−2 at a low overpotential of 42.9 and 39.7 mV in 1 M KOH and 0.5 M H2SO4, respectively. It also possessed high long-term electrolysis durability, and the cell voltage of water electrolysis using self-supporting porous NiCoP-OA-AE||IrO2-Ta2O5 electrolyzer at 500 mA cm−2 for 250 h in 0.5 M H2SO4 is only 2.9 V.