Three-dimensional porous MoNi4 networks constructed by nanosheets as bifunctional electrocatalysts for overall water splitting

Abstract

Non-noble bifunctional electrocatalysts for overall water splitting in alkali water solution are highly attractive. Herein, novel 3D porous MoNi₄ networks constructed by nanosheets show superior catalytic activity and durability towards overall water splitting, rivaling state-of-the-art non-noble bifunctional electrocatalysts. The porous MoNi₄ networks were prepared on porous Ni foam by the hydrothermal process and then with the annealing process in hydrogen. The porous MoNi₄ networks annealed at 450 °C show high activity for both HER and OER. The superior catalytic performance is ascribed to not only being fully reduced into MoNi₄ but also maintaining the original morphology as much as possible after annealing at 450 °C. NiOOH species were formed on the surface of the porous MoNi₄ networks annealed at 450 °C after OER, and the in situ formation of NiOOH leads to excellent activity as well as stability in the OER. The 3D porous MoNi₄ networks annealed at 450 °C need only ∼1.58 V to achieve 10 mA cm⁻² for overall water splitting and exhibit excellent stability without loss of activity after 24 hours. A two-electrode device to split water with porous MoNi₄ networks as bifunctional electrocatalysts can be driven by a single AA battery (1.5 V).