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