Bioinspired, Stimuli-Responsive, Multifunctional Superhydrophobic Surface with Directional Wetting, Adhesion, and Transport of Water

摘要

A novel smart stimuli responsive surface can be fabricated by the subsequent self-assembly of the graphene monolayer and the TiO2 nanofilm on various substrates, that is, fabrics, Si wafers, and polymer thin films. Multiscale application property can be achieved from the interfacial interaction between the hierarchical graphene/TiO2 surface structure and the underlying substrate. The smart surface possesses superhydrophobic property as a result of its hierarchical micro- to nanoscale structural roughness. Upon manipulating the UV induced hydrophilic conversion of TiO2 on graphene/TiO2 surface, smart surface features, such as tunable adhesiveness, wettability, and directional water transport, can be easily obtained. The existence of graphene indeed enhances the electron-hole pair separation efficiency of the photo-active TiO2, as the time required for the TiO2 superhydrophilic conversion is largely reduced. Multifunctional characteristics, such as gas sensing, droplet manipulation, and self-cleaning, are achieved on the smart surface as a result of its robust superhydrophobicity, tunable wettability, and high photo-catalytic activity. It is also revealed that the superhydrophilic conversion of TiO2 is possibly caused by the atomic rearrangement of TiO2 under UV radiation, as a structural transformation from {101} to {001} is observed after the UV treatment.