High-performance bifunctional electrocatalysts of CoFe-LDH/NiCo2O4 heterostructure supported on nickel foam for effective overall water splitting

Abstract

Highly efficient bifunctional electrocatalysts for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) have been extensively explored for overall water splitting. Herein, highly efficient bifunctional NiCo2O4-based heterostructure electrocatalysts have been designed by loading different amount of CoFe-layered double hydroxide on the self-supported nickel foam (CoFe-LDH/NCO/NF-1, CoFe-LDH/NCO/NF-2 and CoFe-LDH/NCO/NF-3) by a facile hydrothermal method. The CoFe-LDH/NCO/NF with optimal amount electrocatalyst enable excellent catalytic activity for OER and HER, such as a small of Tafel slope, low overpotential as well as good stability, surpassing RuO2, Pt/C and the majority of other NiCo2O4 based electrocatalysts. The unprecedented electrocatalytic performance is benefiting from high electrochemical active surface areas, fast charge transfer and strong synergistic effect between CoFe-LDH and NiCo2O4. Furthermore, the optimal CoFe-LDH/NCO/NF-1 as anode and cathode delivers a current density of 10 mA cm−2 at a low cell voltage of 1.65 V and presents good durability in long-term stability test for overall water splitting. This work provides an effective strategy for development of highly efficient NiCo2O4-based electrocatalysts for overall water splitting application in the future.