CoP-nanorod-doped Co heterostructured electrode for efficient electrocatalytic hydrogen evolution reaction

A high-performance CoP-nanorod doped Co metal on Ni foam (CoP/Co/NF) electrocatalytic electrode was designed via a two-step strategy involving electrodeposition and low-temperature phosphorization. The heterogeneous structures of metallic Co and CoP on the Ni foam are expected to provide hierarchical interfaces, which promote the synergistic effect in the electrocatalysis process. The electrode surface shows a hierarchical architecture of sea-urchin-like arrays directly grown on conductive substrates with a large electrochemical active surface area (ECSA) of 537.5 cm², which facilitate rapid bubble release and ensure stable low-energy operation even at high current densities. Electrochemical test results show that the CoP/Co/NF catalyst electrode exhibits an excellent catalytic activity for the hydrogen evolution reaction in 1 M KOH electrolyte. The optimized overpotential reached 23 and 56 mV at a current density of 10 and 100 mA cm^-2 with a low Tafel slope of 27.1 mV dec^-1. The electrode shows good stability after catalytic hydrogen evolution reaction for 100 h at 100 mA cm^-2. Theoretical DFT calculations reveal that the CoP/Co interface serves as an electron-rich center that lowers the energy barrier for water dissociation and optimizes ΔG _H*.