α-Ni(OH)2 electrodeposition from NiCl2 solution

Abstract

Abstract α-Ni(OH)2 was synthesized from a NiCl2 solution by electrodeposition method. In order to conduct a systematic study on the effects of experimental parameters, a series of electrolyte initial pH values, current densities, electrodeposition temperatures, and electrodeposition time were used. Cyclic voltammetry results demonstrated a side reaction of Ni2++2e→Ni. The X-ray diffraction analysis, Fourier-transform infrared spectrum, and the color of the product showed that pure α-Ni(OH)2 could be obtained in the initial pH value range of 2–5.86, current density range of 10–25 mA/cm2 electrodeposition temperature range of 25–35 °C, and electrodeposition time range of 1.0–3.0 h. When electrodeposition temperature increased to 45 °C, a mixture of α-Ni(OH)2 and metallic Ni was obtained. A current density higher than 30 mA/cm2 resulted in the sample with features of β-Ni(OH)2. A small amount of metallic Ni existed in the as-prepared sample when current density decreased to 5 mA/cm2. A slight increase of electrolyte pH was observed with increasing initial solution pH and current density. Electrodeposition mass revealed a slight decrease with initial pH decreasing and showed an almost linear increase with current density increasing. The slope of the curve for electrodeposition mass versus electrodeposition time remained stable in the first 2.0 h and then decreased.