Fe–Ni–Co trimetallic oxide hierarchical nanospheres as high-performance bifunctional electrocatalysts for water electrolysis

Abstract

Water electrolysis is one of the most promising approaches for producing hydrogen. However, the OER, kinetics are sluggish and necessitate highly efficient electrocatalysts to speed up the reaction. In this work, we used NiCo glycerate solid nanospheres as a precursor to construct Fe–Ni–Co trimetallic oxide nanospheres utilizing a solvothermal-annealing and stirring technique. The oxygen evolution reaction (OER) activity of the Fe–Ni–Co spheres was greatly enhanced after Fe doping. Among these samples, the FeNiCo-15 hierarchical yolk–shell spheres needed overpotentials of only 204 and 178 mV for the OER and HER, respectively, to drive a current density of 10 mA cm⁻², and showed good electrochemical stability. Further, it also presented superior electrocatalytic activity in terms of full water splitting, which was comparable to the integrated performance of the Pt|IrO₂ couple. A cell voltage of only 1.61 V was required to attain a current density of 10 mA cm⁻². This paper provides a promising method for developing efficient bifunctional electrocatalysts driving redox electrocatalysis.