Creation of microstructured surfaces using Cu-Ni composite electrodeposition and their application to superhydrophobic surfaces

This research analyzed the influence of the electrodeposition ratio of Cu-Ni on the creation of microstructure in Cu-Ni composite electrodeposition, and identified the microstructure generation mechanism with respect to the Cu-Ni electrodeposition ratio. The concentration of CuSO4 in the electrodeposition solution was varied to 0.00, 0.02, 0.04 M to control the electrodeposition ratio of Cu, and the applied voltage was varied to voltages of −0.9, −1.2, −1.5 V, which were applied to control the electrodeposition ratio of Ni. In the composite electrodeposition, Cu ions precipitated intensively at the top of the structure with a short ion diffusion length, and the Ni ions precipitated regularly throughout the entire area charge transferred. Therefore, the structure showed vertically oriented growth when Cu electrodeposition was dominant, and the structure showed isotropic growth when Ni electrodeposition was dominant. On the other hand, Cu ions precipitation concentration at the tip of the grown structure intensified as the height of the structure increased. Therefore, when a structure grows above a certain height, the excess Cu ions precipitate at the top of the grown structure and a cluster structure composed of spherical Cu particles develops. The microstructure produced in the electrodeposition solution with the CuSO4 concentration of 0.04 M had such a high structure generation density and aspect ratio that it was modified to a superhydrophobic surface with a contact angle higher than 150°, and it manifested an excellent self-cleaning ability.