Electronic modulation and dual-defect construction of NiMoP/Ni2P heterointerfaces for sustainable oxygen evolution reaction

The existence of multiple vacancies leads to significant changes in the local atomic structure, which can regulate the electronic structure of the surface and form unsaturated coordination geometries. However, the current methods employed to generate multiple vacancies in two-dimensional (2D) layered double hydroxide (LDH) materials are still difficult to achieve to some extent and are primarily limited to monolayer LDH structures. Here, we present an improved method to synthesize NiMoP/Ni₂P catalysts with a sponge-like porous structure. Firstly, NiO with dual defects was constructed by subjecting NiMo-LDH/Ni to air calcination. Subsequently, we performed phosphorization treatment and introduced multiple Ni vacancies and O vacancies as defect sites to tune the edge and substrate surfaces of LDH. At the same time, the electronic structure was tuned by adding P heteroatoms. The synergistic effect of porous structure, heterogeneous interfaces, vacancies, doping defects, and amorphous states can greatly enhance the electron transfer effect inside the catalysts, which significantly improves the catalytic ability of the oxygen evolution reaction (OER). Therefore, the overpotential for the oxygen evolution reaction of NiMoP/Ni₂P heterointerfaces reaches 270 mV at a current density of 10 mA·cm⁻² under alkaline conditions, with the catalysts capable of sustaining high current densities even after the durability testing for 35 h.

Graphical abstract