Amorphous NiWO4 nanoparticles boosting the alkaline hydrogen evolution performance of Ni3S2 electrocatalysts

Heazlewoodite nickel sulfide (Ni3S2) has become attractive for electrocatalytic hydrogen evolution reaction (HER). However, strong sulfur-hydrogen bonds (S-H-ads) formed on the surface of Ni3S2 greatly hinder the H-ads desorption and reduce HER activity. Herein, amorphous NiWO4 nanoparticles-decorated Ni3S2 electrocatalysts (NiWO4/Ni3S2) have been constructed via a two-step hydrothermal method. The heterostructures exhibit much better HER performance than original Ni3S2 by delivering current densities of -10 and -100 mA cm(-2) at low overpotentials of 136 and 274 mV, while those for Ni3S2 are 234 and 424 mV, respectively. Moreover, they display ultra-long stability of 75 h. Theoretical calculation proves the improved activity of NiWO4/Ni3S2 heterostructures is attributed to highly active interfaces between amorphous NiWO4 nanoparticles and Ni3S2 electrocatalysts. The strong electronic interaction between NiWO4 and Ni3S2 decreases the local electron density of Ni and S atoms, facilitates water adsorption on Ni-sites and optimizes hydrogen atom adsorption/desorption on adjacent S-sites with weakened S-H-ads.