Hierarchical self-assembly of NiFe-LDH nanosheets on CoFe2O4@Co3S4 nanowires for enhanced overall water splitting

Abstract

Developing noble-metal-free, high-efficiency, and durable electrocatalysts for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) is a challenging problem in electrochemical water electrolysis. In this work, a facile continuous two-step hydrothermal method followed by electrodeposition to fabricate NiFe-LDH integrated with CoFe₂O₄@Co₃S₄ nanoflowers supported by carbon fiber paper (NiFe-CoFe₂O₄@Co₃S₄/CFP) as a full water-splitting electrocatalyst was developed. Serving as an anode catalyst, the fabricated heterostructure electrode shows extraordinary OER performance with an overpotential of 233.3 and 244.0 mV to achieve a current density of 50 and 100 mA cm⁻², respectively. Serving as a cathode catalyst, NiFe-CoFe₂O₄@Co₃S₄/CFP exhibits superior electrocatalytic activities with an overpotential of 98 mV to achieve current densities of 10 mA cm⁻². Furthermore, when serving as both the anode and cathode catalyst in an electrolyzer for overall water splitting, the as-prepared electrode only requires a cell potential as low as 1.53 V to reach a current density of 10 mA cm⁻² and excellent durability for more than 48 h in alkaline media.