Self-supporting CoP-C nanosheet arrays derived from a metal–organic framework as synergistic catalysts for efficient water splitting

Here, a new strategy that combines accessible active sites and multiphase synergy in a simple process is developed for constructing bifunctional electrocatalysts toward overall water splitting. By using metal-organic framework nanosheets hydrothermally grown on the pre-oxidized nickel foam (denoted by Co2(OH)2(BDC)/NiO/NF) as a precursor, two novel heterogeneous nanosheet arrays including cobalt phosphide nanoparticles embedded carbon nanotubes nanosheet array supported by the phosphatized nickel foam (denoted by CoP-CNT/Ni2P/NF) and cobalt phosphide nanorods decorated carbon nanosheet array supported by the oxidized nickel foam (denoted by CoP-C/NiO/NF) are prepared. Both were confirmed to be high-efficient for hydrogen and oxygen evolution reactions. Especially, CoP-C/NiO/NF exhibits the higher catalytic activity toward hydrogen evolution reaction (η100 = -131 mV), promoted by the synergy of oxidized nickel foam. CoP-CNT/Ni2P/NF performs better in the oxygen evolution reaction (η50 = 301 mV), benefiting mainly from its improved electrochemically active surface area. The two catalysts match well in overall water splitting with satisfactory activity (η10 = 1.57 V ) and stability when directly applied in a two-electrode cell. This method will bring new inspiration to maximize the electrocatalytic efficiency of MOF-derived catalysts for energy conversion applications in the future.