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

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 degree 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 degree C. NiOOH species were formed on the surface of the porous MoNi4 networks annealed at 450 degree 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 degree C need only similar to 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).