Efficient Hydrogen Evolution on Cu Nanodots-Decorated Ni₃S₂ Nanotubes by Optimizing Atomic Hydrogen Adsorption and Desorption

Low-cost transition-metal dichalcogenides (MS 2 ) have attracted great interest as alternative catalysts for hydrogen evolution. However, a significant challenge is the formation of sulfur–hydrogen bonds on MS 2 (S–H ads ), which will severely suppress hydrogen evolution reaction (HER). Here we report Cu nanodots (NDs)-decorated Ni 3 S 2 nanotubes (NTs) supported on carbon fibers (CFs) (Cu NDs/Ni 3 S 2 NTs-CFs) as efficient electrocatalysts for HER in alkaline media. The electronic interactions between Cu and Ni 3 S 2 result in Cu NDs that are positively charged and can promote water adsorption and activation. Meanwhile, Ni 3 S 2 NTs are negatively charged and can weaken S–H ads bonds formed on catalyst surfaces. Therefore, the Cu/Ni 3 S 2 hybrids can optimize H adsorption and desorption on electrocatalysts and can promote both Volmer and Heyrovsky steps of HER. The strong interactions between Cu and Ni 3 S 2 cause the Cu NDs/Ni 3 S 2 NTs-CFs electrocatalysts to exhibit the outstanding HER catalytic performance with low onset potential, high catalytic activity, and excellent stability.