Fluorine-Anion-Modulated Electron Structure of Nickel Sulfide Nanosheet Arrays for Alkaline Hydrogen Evolution

Exploration of earth-abundant transition-metal sulfide electrocatalysts with Pt-like activity toward alkaline hydrogen evolution reaction (HER) is significant for future global energy supply but still a challenge. Herein, we rationally designed and fabricated a self-supported F-anion-doped Ni3S2 nanosheet array grown on Ni foam (F-Ni3S2/NF) with enhanced HER performance in alkaline media. The obtained catalyst exhibits a low overpotential of 38 mV at 10 mA cm(-2) with a Tafel slope of 78 mV dec(-1) and can sustain for 30 h, which is comparable to commercial Pt/C catalysts. X-ray photoelectron spectroscopy, synchrotron-based X-ray absorption fine structure, and density functional theory analysis simultaneously demonstrate the successful modulation of the electronic structure of Ni3S2 by substitutional F doping. This work not only provides atomic-level insight into adjusting the electronic structure of metal sulfides through anion engineering but also opens an avenue for reasonable design of advanced earth-abundant electrocatalysts toward HER and beyond.