Effect of Corrosion Potential on the Structure and Properties of Nanoporous Nickel

Taking the Ni–Mn alloy with 25% Ni as the precursor, nanoporous nickel (NPN) was fabricated by electrochemical dealloying, and the effect of corrosion potential on the material microstructure and electrochemical performance was studied in the article. Morphology, element species, content and phase of the sample were characterized and analyzed by scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and X-ray diffractometer (XRD). Different from the previously report that the material surface presented the structure of “mud crack”, materials prepared in this article remained the porous skeleton structure, but also reduced the large cracks and increased the hairline cracks. After a deep research, it is found that the corrosion potential determines the morphology and structure of porous material. This was due to the fact that corrosion rate became quicker when the corrosion voltage was higher and the degree of corrosion increased accordingly; precursor alloy defects increased as the dissolution of Mn, and the internal stress increased as a result; in addition, the diffusion rate of Ni was so low that it couldn’t refill the vacancy of Mn timely, and then more cracks occurred, therefore there were significant differences for the number and size of cracks. In order to further understand the electrochemical performance of the electrode material prepared under a proper potential, cyclic voltammetry and charge-discharge technology were used to characterize the electrochemical performance of NPN. The results show that the specific capacitance of NPN was 1.69 F cm⁻² which is 3 times of that of the nanoporous nickel martial reported previously. Therefore the prepared nanocomposite nickel in this article is a high-quality electrode capacitor material.