Morphology-controllable gold hierarchically micro/nanostructured arrays prepared by electrodeposition on colloidal monolayer and their structurally related wettability

In this paper, we demonstrated a clean fabrication of the morphology-controllable gold hierarchically micro/nanostructured arrays (HMNAs) by electrochemical deposition on polystyrene monolayer colloidal crystal template. Through varying cathodic current density and deposition time to adjust electrocrystallization process, the HMNAs can be controlled from the one with microspheres and nanoparticles to the one with microbowls and nanorods. Further adjusting the nucleating sites via ion-sputtering deposition of gold film over the polystyrene spheres, we designed and prepared a new kind of HMNA with microspheres and nanowimbles. Interestingly, these Au HMNAs exhibited structurally related wettability. Correlated with their different hierarchical micro/nano-structures, they all showed superhydrophobicity after surface modification of low surface free energy material while with different surface adhesions. A water droplet can pine on the surface of the concave Au HMNA with microbowls and nanorods even turned upside down, showing ultrahigh liquid-solid adhesion. However, the convex Au HMNA with microspheres and nanowimbles shows very low surface adhesion with a sliding angle close to zero. These surface adhesion-controlled superhydrophobic surfaces can be found many potential applications, such as self-cleaning surfaces, liquid transportation, and multifunctional microfluidic devices.