A novel electrochemical process to prepare a high-porosity manganese oxide electrode with promising pseudocapacitive performance

A nanoporous nickel (Ni) substrate was successfully prepared by selective dissolution of copper (Cu) from a Ni–Cu alloy layer. It was noted that both the Cu etching and the Ni/Cu codeposition processes could be performed in the same solution. Afterwards, anodic deposition was carried out to disperse fibrous manganese (Mn) oxide onto the nanoporous Ni substrate. As a result, a novel oxide electrode with a high-porosity structure was fabricated by the totally electrochemical procedure, which is very simple and efficient. Pseudocapacitive performance of this oxide electrode was evaluated by cyclic voltammetry in 0.1 M Na2SO4 solution. The data indicated that specific capacitance of the Mn oxide was as high as 502 F g−1, which was 85% higher than that deposited on a flat electrode. Capacitance retained ratio after 500 charge–discharge cycles of the Mn oxide was also significantly improved from 75 to 93% due to the use of the nanoporous substrate.