Co-doped NixPy loading on Co3O4 embedded in Ni foam as a hierarchically porous self-supported electrode for overall water splitting

Abstract It had remained a challenge to rationally design a highly efficient bifunctional catalyst for overall water splitting using non-precious metals. Herein, a simple method was presented to synthesize a self-supported catalyst using nickel foam (NF) filled with nanoscale Co3O4 (Co3O4/NF) as a hierarchical porous support. A NiCoP alloy was deposited on the Co3O4/NF in the form of profiling growth by electroless plating (NiCoP@Co3O4/NF). And then, the NiCoP@Co3O4/NF electrodes were phosphorylated. The profile-grown NiCoP alloy transformed into a two-dimensional (2D) flake-like Co-doped NixPy, forming a self-supported electrocatalyst (Co-NixPy@Co3O4/NF). The Co-NixPy@Co3O4/NF electrode exhibited a large surface area, excellent conductivity, and synergy between metal atoms. This electrode also possessed low overpotentials of 72 and 120 mV to drive the hydrogen and oxygen evolution reactions at 10 mA cm−2. For overall water splitting, the self-supported Co-NixPy@Co3O4/NF electrode only required a low voltage of 1.47 V to reach the current densities of 20 mA cm−2 in 1 M KOH with long-term stability for 36 h. This work represented an achievement the exploration of a new bifunctional of transition metal phosphides with high performances in water splitting.