Reinforced interfacial coupling effect of NiO/NiP by Fe doping for boosting water splitting.

Nickel-based catalysts are suitable for water splitting to generate hydrogen. However, the low conductivity and weak stability have always been urgent issues to be addressed in nickel-based catalysts. Fe-doped nickel oxide/nickel phosphide (Fe-NiO/NiP) was prepared as a bifunctional electrocatalyst by doping metal and constructing heterogeneous interface. The introduction of Fe contributed to the reinforced interfacial coupling effect of NiO/NiP to promote charge transfer and accelerate reaction kinetics. The heterojunction regulated the interfacial charge density between NiO and NiP to improve the electronic environment of Ni and enhance conductivity. The O-Fe-P bond at the heterogeneous interface induced the directional transfer of electrons and ensured the structure stability. The synergistic effect of Fe doping and heterogeneous interface increased the adsorption energy of *O and coordinated the adsorption energy of *H, advancing the catalytic performance. Fe-NiO/NiP exhibited the overpotential of 242 mV and 141 mV at 10 mA cm for oxygen and hydrogen evolution, respectively.