Template-Free Electrochemical Deposition and Characterization of Ni Nano/Microrod Arrays

Vertical aligned arrays of Ni nano/microrods have been successfully fabricated via a galvanostatic electrolysis on Ti substrates without any hard templates and surfactants. Electrodeposition and cyclic voltammetry were conducted in a conventional three-electrode glass cell. Cyclic voltammetry was used to study the electrochemical reactions relevant to the film growth. The transfer coefficient and diffusion coefficient of Ni(II) became smaller with the decrease of the reaction temperature. SEM images indicate that the aspect ratio of the nano/microrods is about 11 and 3, respectively. It is found that the various morphologies of the products are dependent on the electrodeposition conditions, such as the deposition current densities, kinds of additives, substrates, pH, and deposition temperature. X-ray diffraction patterns show that the as-deposited nano/microrods are all cubic phase of Ni. TEM analyzes confirm the Ni microrods are single crystal and nanorods polycrystalline, respectively. The anti-corrosion property of Ni film with a polycrystalline structure is poor for its high degree of surface defects. Both the Ni nano/micro arrays exhibit excellent soft magnetic properties at room temperature and ferromagnetism at 5 K. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.027207jes] All rights reserved.