Effect of Acidity on the Morphology, Structure, and Composition of Ni Nanotubes

The behavior of Ni nanotubes 12 µm long and 400 nm in diameter, synthesized via electrochemical deposition in the pores of polymer ion track membranes, is studied in media of different acidities. Prolonged exposure to acid degrades Ni nanotube walls, due to the formation of oxides whose volume grows along with the pH of the medium. Large amounts of nickel(II) and (III) oxides are found to embrittle and partially destroy nanotube walls. The intense oxidation processes in acidic media suggest the use of precoated nickel nanotubes in devices operating in aggressive environments.