Electro-deposition of nickel–iron nanoparticles on flower-like MnCo2O4 nanowires as an efficient bifunctional electrocatalyst for overall water splitting

Abstract

Exploitation of earth-abundant, highly efficient, and durable bifunctional electrocatalysts for overall water splitting is of great importance to meet renewable energy demands. Herein, a 3D hierarchical heterostructure amorphous NiFe hydroxide electrodeposited on MnCo₂O₄ supported on Ni–Fe foam (NFF) electrode (denoted as NiFe–MnCo₂O₄/NFF) was successfully synthesized through a facile method for an efficient oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Benefiting from the strong synergetic coupling effect between NiFe nanoparticles and MnCo₂O₄ nanowires, the as-obtained NiFe–MnCo₂O₄/NFF exhibits excellent electrocatalytic activities with a low overpotential of 272 mV to deliver a current density of 100 mA cm⁻² for the OER and a moderate overpotential of 98 mV at a current density of 10 mA cm⁻² for the HER. When used as both a cathode and anode for overall water splitting in a two-electrode configuration (1 M KOH aqueous electrolyte), NiFe–MnCo₂O₄/NFF exhibits outstanding activity (an external voltage of 1.49 V to drive a stable current density of 10 mA cm⁻²) and impressive durability (no obvious degradation at a constant voltage up to 48 h). This interesting study provides a solid step towards enhancing the electrocatalytic activity of non-precious electrocatalysts for water electrolysis.