Constructing microstructures in nickel-iron layered double hydroxide electrocatalysts by cobalt doping for efficient overall water splitting

Abstract

The development of Ni–Fe layered double hydroxide (NiFe LDH) catalysts for overall water splitting (OWS) is urgently required. NiFe LDHs are promising catalysts for the oxygen evolution reaction (OER). However, their hydrogen evolution reaction (HER) performance is restricted by slow kinetics. The construction of multiple types of active sites to simultaneously optimise the OER and HER performance is significant for OWS using NiFe LDHs. Hence, a Co-doped NiFe LDH electrocatalyst with dislocations and stacking faults was designed to modulate the electronic structure and generate multiple types of activity sites. The Co0.03-NiFe0.97 LDH catalyst only required overpotentials of 280 (50 mA cm−2, OER) and 170 mV (10 mA cm−2, HER). However, it reached a current density of 50 mA cm−2 at 1.53 V during OWS. Co0.03-NiFe0.97 LDHs could be stabilised for 140 h at 1.52 V. Furthermore, Co0.03-NiFe0.97 LDHs exhibited a higher electrocatalytic activity than commercial Raney nickel and Pt/C||IrO2 under industrial conditions. The significant specific surface area, high conductivity, and unique microstructures are the major factors contributing to the excellent OWS performance. This study suggests an efficient strategy for introducing microstructures to fabricate catalysts with high activity for application in OWS.