Bifunctional CuCo2O4/CoOOH as a synergistic catalyst supported on nickel foam for alkaline overall water splitting

Designing efficient, affordable and stable bifunctional electrocatalysts is critical for electrochemical water splitting. Herein, distinctive CuCo 2 O 4 /CoOOH supported on 3D porous nickel foam was synthesized successfully via annealing and green hydrothermal strategies. Importantly, this unique catalyst with the synergistic effect can exhibit superior electrocatalytic activity, which only requires 125 mV (η 10 ) for HER and 217 mV (η 20 ) for OER. Remarkably, CuCo 2 O 4 /CoOOH/NF shows a voltage of 1.583 V to drive a current density of 10 mA cm -2 . The excellent performances can be ascribed to the synergistic effect between CuCo 2 O 4 /NF and CoOOH/NF. In addition, the high-conductive 3D nickel foam substrate and the reciprocally permeated nanosheet can improve electrical conductivity, accelerate reaction kinetics and provide massive exposed active sites. This study provides a novel insight into the facile preparation of bifunctional electrocatalysts, which boosts the electrocatalytic performance for electrolysis of water. • CuCo 2 O 4 /CoOOH supported on nickel foam is prepared by green hydrothermal method. • It needs ultralow overpotentials for HER ( η 10 =125 mV) and OER ( η 20 =217 mV). • The outstanding performances are attributed to the strong synergistic effect between CuCo 2 O 4 /NF and CoOOH/NF, the unique nanosheet structure and the high-conductive 3D nickel foam substrate.