Electrodeposition of Ni-P alloy from deep eutectic solvent and its electrocatalytic activity toward hydrogen evolution reaction

Ni-P alloys have been successfully electrodeposited in the choline chloride and ethylene glycol with a molar proportion of 1:2(CE) electrolyte and their activities toward hydrogen evolution reaction (HER) have been also evaluated. The electrodeposition of Ni-P alloy follows a co-deposition process, and the bulk growth of which depends on an instantaneous nucleation under diffusion control. The morphologies of Ni-P alloys are significantly influenced by the P content, and low P content can lead to a smooth surface. As expected, Ni-9.0 wt.% P alloy shows an impressive HER catalytic performance with a Tafel slope (b) of 72.9 mV dec −1 and an overpotential of 105 mV at 50 mA, in agreement with its large ECSA ( C dl = 3.25 mF cm −2 ) and small interface charge-transfer resistance. More interestingly, Ni-9.0 wt.% P alloy exhibits a sustainable catalytic activity toward HER after 1000 cycling test with a tiny potential decline of ~10 mV at 100 mA cm −2 . Such a striking HER activity of Ni-9.0 wt.% P alloy can be attributed to the synergistic effect among the induced active sites from lattice contraction, negatively charged P incorporation, and a mixed nanometre crystal and amorphous structure. Thus, Ni-P alloy electrodeposited in a CE-based electrolyte can be used as a promising electrode material with high HER activity in alkaline solutions for hydrogen production.