Mechanism investigation of α-Ni(OH)_2 electrodeposition from a NiCl_2 solution

摘要

alpha-Ni(OH)(2) was electrodeposited from NiCl2 solution by membrane electrolysis method. Various ethanol contents and concentration electrolytes were used to investigate the relevant mechanism. XRD and CV results demonstrated a preferentially conducted side reaction of Ni2+ to Ni. Ethanol was proved to be effective to poison this reaction. Linear relationships of the product mass and electrodeposition time for electrodepositions in 0.1 M NiCl2 solutions indicated an ignored output of Ni. A four-step mechanism for Ni(OH)(2) electrodeposition from the side reaction priority system was proposed. XRD and FT-IR results suggested beta-Ni(OH)(2) and alpha-Ni(OH)(2) were certain to be synthesized in 0.05-0.1 and 0.2-1.0 M NiCl2 solution. beta-Ni(OH)(2) formed in these low concentration electrolytes was proved to be prevented by circulating the cathodic electrolyte. Analyses suggested beta-Ni(OH)(2) formed in the present cases might be either converted from alpha-Ni(OH)(2) under high alkaline digestion or synthesized originally due to the proper ratio of Ni2+ and OH-. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.