Enhanced hydrogen evolution activity of Ni/Ni₃S₂ nanosheet grown on Ti Mesh by Cu Doped Ni

Optimizing electronic structure and surface morphology are of great importance to achieve highly active and stable electrocatalyst for hydrogen evolution reaction (HER). In this paper, the vertically aligned Cu doped Ni/Ni₃S₂ nanosheet was successfully deposited on Ti mesh (NiCu_x/Ni₃S₂/TM, x = Cu/Ni atomic ratio in NiCu_x) by facile electrodeposition method. Phase composition, surface morphology and electronic structure information were characterized by XRD, SEM, TEM and XPS. The results unraveled that Cu doping induced the changes in both electronic structure and surface morphology of Ni/Ni₃S₂ sample, which were in favor of promoting the breakage of H-O bond in H₂O and optimizing Ni-Hads adsorption energy, thus improving HER activity with decreased overpotential at-10 mA/cm² by 202mV. The influence of Cu(NO₃)₂ precursor content onHER activity of as-preparedNiCu_x/Ni₃S₂/ TM was investigated. NiCu_0.57/Ni₃S₂/TM prepared with 1.2 mM Cu(NO₃)₂ exhibited the highest electrocatalytic activity toward HER with overpotential of 239 mV at -10 mA/cm2 and Tafel slope of 86 mV/dec. The enhanced activity and superior stability for NiCu_0.57/Ni₃S₂/TM were ascribed to the change in electronic structure and surface morphology.