Electrodeposition of nano-nickel in deep eutectic solvents for hydrogen evolution reaction in alkaline solution

Abstract The electrodeposition of nano-Ni films on a Cu substrate from NiCl 2 precursors in choline chloride (ChCl)/urea or ethylene glycol (EG) based deep eutectic solvent (DES) was illustrated. Voltammetric study demonstrates that the electrodeposition of Ni(Ⅱ) in both ChCl/urea and ChCl/EG systems is a simple one-step reaction process, and the electrochemical process is a typical diffusion-controlled irreversible process. The obtained Ni films can be controlled to form nanostructures depending on the DES and the electrodeposition conditions. The nanostructured Ni films were investigated as electrodes for hydrogen evolution reaction (HER) in an alkaline medium. The enhanced catalytic activity toward the HER was confirmed, which is mainly attributed to the formation of needles morphology and the improved electrochemical surface area. The result reveals that the electrodeposition process may provide a promising strategy for the production of nano-Ni at low temperature for HER.