Switching of Hydrophilic to Super-Hydrophilic Behaviour in Spray Deposited Au-Doped SnO2 Thin Films for Self Cleaning Applications

In this paper, nanocrystalline pure and Gold (Au) doped Tin Oxide (SnO2) thin films were successfully deposited by simple and inexpensive 'Spray Pyrolysis' technique. These films have been characterized by X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) and Atomic Force Microscopy (AFM). XRD results showed that the deposited films have tetragonal rutile structure with average crystalline size of 8-20 nanometers. The wettability of the deposited films was investigated using water contact angle measurement technique (GBX Model Digidrop). Hydrophilic nature of SnO2 films represented by water contact angle (WCA) of 46 degrees was modified to super-hydrophilic WCA = 9 degrees at 4 wt% Au-doped SnO2 thin films. Our analysis reveals that the super-hydrophilic properties 4 wt% Au-doped SnO2 thin films can be useful in self-cleaning applications.