Example 7
A piece of rolled commercial nickel foam (2.5×4 cm2, 200 μm in thickness, MTI Corporation, CA, USA) was soaked in sulfuric acid (H2SO4, 1M) for 20 min to remove the native nickel oxide layer. Then, a thin layer of Cu film was electroplated at −1.8V (vs. Ag/AgCl) for 800 coulombs from an electrolyte made of copper sulfate (CuSO4, 2M) and boric acid (H3BO3, 1M) with copper foil serving as the counter electrode (MTI Corporation, CA, USA). Next, the Cu—Ni composite foams were annealed at a temperature of 1000° C. in a gas flow of hydrogen (H2, 5 sccm) and nitrogen (N2, 50 sccm) at 420 mTorr for 5 min. Finally, the annealed composite was electrochemically etched at +0.6 V (vs. Ag/AgCl) in the same electrolyte for 350 coulombs, resulting in large arrays of micropores uniformly distributed on the interconnected microstruts of the foam.
