Boosting Alkaline Hydrogen Evolution Reaction by Modulating D-Band Center in Bimetallic Sulfide NiS-FeS Heterointerfaces.

Hydrogen evolution reaction (HER) in alkaline electrolytes is considered to be the most promising industry-scale hydrogen (H) 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 NiS-FeS heterojunction nanoarray on the commercial Ni foam (NiS-FeS@NF). The as-prepared NiS-FeS@NF catalyst only requires a low overpotential of 71 and 270 mV to reach the current density of 10 and 500 mA cm with a long-lasting lifetime of over 200 h. Moreover, the NiS-FeS@NF catalyst can operate at industrial conditions (500 mA cm 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 NiS 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.