Effect of Cation Substitution in Spinel MFe₂O₄ and Its Integration with NiCo LDH toward Efficient Hydrogen Evolution Catalysis

Abstract

Developing efficient and affordable electrocatalysts for green hydrogen production is essential to address rising energy demands and environmental challenges. In this work, a MnFe₂O₄/NiCo layered double hydroxide (LDH) heterostructure electrocatalyst was synthesized on Ni foam through a simple in situ hydrothermal method for enhanced hydrogen evolution reaction (HER) performance. Comparative analysis of cation-substituted ferrites (MnFe₂O₄, NiFe₂O₄, ZnFe₂O₄) revealed that MnFe₂O₄ offers superior catalytic activity due to its favorable cation distribution, improved conductivity, and abundant redox-active sites. Integrating MnFe₂O₄ with NiCo LDH nanosheets significantly boosted charge transfer, active site exposure, and proton adsorption–desorption kinetics. The optimized MnFe₂O₄/NiCo LDH (30 wt%) composite achieved an overpotential of 240 mV at 10 mA cm⁻² and a low Tafel slope of 56 mV dec⁻¹ in 1.0 M KOH. This strong synergistic coupling and robust structural stability highlight its potential as a high-performance, non-noble metal electrocatalyst for sustainable water splitting and green hydrogen production.