Bioenzyme Inspired Heterointerface Construction of NiFeSe/Ni₃S₂ for Improved Overall Water Splitting

Electrocatalytic water splitting for hydrogen production represents a crucial pathway toward establishing sustainable energy infrastructure and addressing environmental concerns, with the development of high-performance nonprecious metal catalysts being a central focus. While Ni₃S₂ demonstrates potential as an electrocatalyst, its limited functionality and suboptimal performance necessitate further enhancement. In this study, drawing inspiration from natural hydrogenases, we engineered a novel NiFeSe/Ni₃S₂ composite electrocatalyst through the integration of NiFeSe with Ni₃S₂. The synthesized catalyst displayed outstanding overall water-splitting performance in alkaline media, realizing current densities of 100 and 10 mA cm^-2 at remarkably low overpotentials of 267.4 mV (vs RHE) for oxygen evolution reaction (OER) and 105.6 mV (vs RHE) for hydrogen evolution reaction (HER), respectively. Remarkably, the two-electrode electrolyzer incorporating NiFeSe/Ni₃S₂ achieved a current density of 20 mA cm^-2 at a substantially reduced cell voltage of 1.586 V. Comprehensive analysis revealed that the strategic construction of biomimetic active centers and heterogeneous interfaces significantly modulates the electronic structure, improved charge transfer, and redistribution of electron density of the catalytic sites. This investigation provides valuable insights and a promising framework for the rational design of high-performance bifunctional electrocatalysts for water-splitting applications.