Nanoporous Nickel Fabricated by Dealloying of Rolled Ni-Mn Sheet

Abstract

Metallic nanoporous architecture can be spontaneously attained by dealloying of a binary alloy. Nanoporous nickel are fabricated by dealloying rolled Ni-Mn sheet. Unlike Ni-Al alloy, the initial Ni-Mn alloys had good cold workability because of their fcc crystal structures. After the electrolysis of the alloys in (NH₄)₂SO₄ aqueous solution, nanoporous architecture of Ni with pore sizes of 10–20 nm was confirmed. Also, a nanoporous/bulk bilayer-stacked Ni electrochemical actuator sheet was fabricated. The stacked bilayer sheet composed of bulk and nanoporous Ni reversibly deformed when a potential of ±1 V was applied in aqueous NaOH solution. The electrochemical actuation is considered to have a strong relationship with the electrical double layer, because cyclic voltammetric measurements suggested that the effect of oxygen adsorption on the surface was minor. The results suggest that nanoporous Ni can be used as an actuator, and it has potential in being applied for commercial use because of its low price and high availability.