Synthesis of coaxial TiO2/In2O3 nanowire assembly using glancing angle deposition for wettability application

Abstract

Coaxial TiO2/In2O3 nanowire (NW) assembly, TiO2 NW and In2O3 NW were synthesized incorporating glancing angle deposition technique inside electron beam evaporator and their structural and optical properties were analyzed. The field emission scanning electron microscopy and transmission electron microscopy confirmed the growth of TiO2/In2O3 NW. X-ray diffraction confirmed the polycrystalline nature of the deposited TiO2/In2O3 NW structure. The surface roughness was 2.12 nm, 6 nm and 6.35 nm for TiO2 NW, In2O3 NW and TiO2/In2O3 NW, respectively using atomic force microscope. The TiO2/In2O3 NW, bare TiO2 NW and In2O3 NW showed water contact angle (CA) of 129°, 68° and 123°, respectively. On exposure to UV light illumination, the surface CA of coaxial TiO2/In2O3 NW, TiO2 NW and In2O3 NW changed to nearly 10°, 30° and 71°, respectively in 1 h. TiO2/In2O3 NW, TiO2 NW and In2O3 NW CAs changed with wettability transition rate of 1.2 × 10−3 degree−1 min−1, 3.2 × 10−4 degree−1 min−1 and 9.2 × 10−5 degree−1 min−1, respectively. There is improvement in photo-induced wettability switching properties of coaxial TiO2/In2O3 NW compared to TiO2 NW and In2O3 NW. This improvement is due to the interfacial surface morphology modification between TiO2 and In2O3 and efficient interaction of separated photogenerated charge carriers with water molecules to adsorb on the surface. On account of these, the change in wettability of heterostructure surface on interaction with UV light can give prospective applications in smart films as antifogging and self-cleaning surfaces.