Ni₃S₂ nanocrystals in-situ grown on Ni foam as highly efficient electrocatalysts for alkaline hydrogen evolution

The exploitation of cost-efficient electrocatalysts is critical to develop the hydrogen evolution reaction (HER) for hydrogen production. Herein, Ni₃S₂/NF-x h (x = 12, 16 and 20, reaction time) nanocrystals in-situ grown on Ni foam (NF) were prepared via a facile hydrothermal method. The results demonstrate that the reaction time plays key roles in the morphology, the hydrogen evolution performance of the samples, and the hydrogen brittleness of NF substrate. Interestingly, the Ni₃S₂/NF-16 h displays outstanding catalytic activity for HER in alkaline solution and avoids the hydrogen brittleness of the NF skeletons simultaneously. To afford a catalytic current of 20 mA·cm⁻², Ni₃S₂/NF-16 h presents ultra-low overpotential of 48 mV for hydrogen evolution and sufficient stability for 40 h. Moreover, the density functional theory (DFT) calculations revealed that the excellent electrocatalytic HER activity of Ni₃S₂ could be attributed to its exposed (015) plane, which exhibited good capability for water adsorption and dissociation in an alkaline electrolyte, leading to the optimal free energy for H* adsorption. The present work offers a novel strategy to design, synthesize and develop highly efficient electrocatalysts for HER.