Boosting Alkaline Hydrogen Evolution Reaction by Modulating D‐Band Center in Bimetallic Sulfide Ni₃S₂‐FeS Heterointerfaces

Abstract Hydrogen evolution reaction (HER) in alkaline electrolytes is considered to be the most promising industry‐scale hydrogen (H₂) production method but is limited to the lack of low‐cost, efficient, and stable HER catalysts. Here, a universal and scalable electrodeposition‐sulfidization modulation strategy is developed to directly grow the Ni₃S₂‐FeS heterojunction nanoarray on the commercial Ni foam (Ni₃S₂‐FeS@NF). The as‐prepared Ni₃S₂‐FeS@NF catalyst only requires a low overpotential of 71 and 270 mV to reach the current density of 10 and 500 mA cm⁻² with a long‐lasting lifetime of over 200 h. Moreover, the Ni₃S₂‐FeS@NF catalyst can operate at industrial conditions (500 mA cm⁻² at 70 °C) for over 200 h stably at a low cell voltage of 1.71 V in an alkaline exchange membrane water electrolysis (AEMWE) device, which indicates a great prospect for practical application. In addition, in situ Raman experiments and density functional theory (DFT) calculations reveal that the downshift of the d‐band center and interfacial synergistic actions due to the electron transfer between Ni₃S₂ and FeS reduce the water spitting energy barrier and optimize H/O‐containing intermediates absorption, thereby improving the HER intrinsic catalytic activity. This work provides an atomic‐level insight into designing efficient HER heterogeneous catalysts.