Fabrication of superhydrophobic niobium pentoxide thin films by anodization

We report a simple method to fabricate a niobium oxide film with a lotus-like micro-nano surface structure. Self-assembled niobium pentoxide (Nb2O5) films with superhydrophobic property were fabricated by an anodization and a hydrophobic treatment. This process has several advantages such as low cost, simplicity and easy coverage of a large area. The surface of fabricated Nb2O5 film was changed from hydrophilic to superhydrophobic surface by a treatment using fluoroaldyltrimethoxysilane (FAS) solution. This value is considered to be the lowest surface free energy of any solid, based on the alignment of CF3 groups on the surface. In particular, among FAS coated surfaces, the micro-nano complex cone structured Nb2O5 film showed the highest water-repellent property with a static contact angle of ca. 162°. This study gives promising routes from biomimetic superhydrophobic surfaces.