Hierarchical architecture of a superhydrophobic Cd-Si co-doped TiO2 thin film

Superhydrophobic coatings have various applications in the industries for successful control and removal of droplets from the surface. Hierarchical structures are promising to achieve a superhydrophobic surface. We fabricated a Cd-Si co-doped TiO2 hierarchical coating on the surface of a glass slide, exhibiting superhydrophobic properties. Cd-Si co-doped TiO2 thin films were prepared by a sol-gel dip-coating method. The morphology, the dominant TiO2 phase, and the crystal structure of the thin films were studied by the concentration of the Si dopant and the calcination temperature. Accordingly, the optical bandgap, surface chemical ligands, and surface topography of thin films also investigated. The lowest bandgap energy (3.23 +/- 0.004 eV) was obtained for the sample with 5 wt% Cd and 20 wt% Si. Moreover, by increasing the calcination temperature of a sample with 5% Cd and 10% Si, the water contact angle was increased from 112.2 degrees +/- 6 degrees to 168.5 degrees +/- 7 degrees, due to the synergy effect of surface ligands and hierarchical structure.