Stepwise anodic electrodeposition of nanoporous NiOOH/Ni(OH)₂ with controllable wettability and its applications

A nanostructured surface with diverse wettability which has the properties of superhydrophilicity, superhydrophobicity and distinguished wetting contrast is important to several key technologies. To meet these requirements, a facile and cost-effective approach via the electrochemical fabrication of a nano-sponge-like nickel oxyhydroxide/nickel hydroxide film on conductive glass followed by the application of external stimuli or chemical treatments is presented. The external stimuli of an environmental chamber and UV/ozone can dynamically and selectively control the aspect of wettability between hydrophobic and superhydrophilic in a short period. In addition, the aid of a chemical treatment with self-assembled non-fluorinated silane on annealed nickel hydroxide film can result in superhydrophobicity without degradation of optical transparency. The effectiveness of these achieved functions is demonstrated using transparent 2D microfluidic channels and direct selective electroplating.