Hierarchical MnCo2O4 nanowire@NiFe layered double hydroxide nanosheet heterostructures on Ni foam for overall water splitting

Abstract

It is of great importance to construct non-precious metal bifunctional electrocatalysts with low cost and high efficiency for overall water splitting. In this work, a nickel foam (NF) supported hierarchical MnCo₂O₄ nanowire@NiFe layered double hydroxide (LDH) heterostructure (labeled as MCO@NiFe-LDH/NF) was constructed using a hydrothermal-annealing-hydrothermal route. Electrochemical tests showed that the as-constructed MCO@NiFe-LDH/NF could be used as an integral electrode for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in 1 M KOH electrolyte. To get the current density of −10 mA cm⁻² for HER or 100 mA cm⁻² for OER, an overpotential of 129/283 mV was separately required. In a two-electrode system with MCO@NiFe-LDH/NF as both the anode and cathode, 1.55/1.705 V of cell voltage was needed to reach current density of 10/100 mA cm⁻². More importantly, the as-constructed integral electrode could continuously catalyze for 200 h, full water splitting at the current density of 50 mA cm⁻², demonstrating prominent long-term stability.