Document Type : Original Article
Department of Physics, Yazd University, Yazd, Iran
Department of Physics, University of Tehran, Tehran, Iran
Department of Physics, Garmian University, Kalar, KRG, Iraq
This paper describes the changes in TiO2/SiO2 nanolayers properties induced by Ultraviolet- visible spectroscopy (UV) irradiation in terms of hydrophilicity/photocatalycity. The TiO2/SiO2 nano particles were synthesized by the sol-gel method and deposited on soda-lime glass by dip-coating. X-ray diffraction (XRD) of the TiO2 particles showed that the nano-particles were crystallized in anatase crystal structure with a crystallite size of ~12 nm. The morphology and surface roughness of TiO2 nanolayer were observed by scanning electron microscope (SEM) and atomic force microscopy (AFM) analysis. The surface roughness (Ra) for TiO2/Glass and TiO2/SiO2 was measured ~ 5 and 19 nm, respectively. The hardness of nanolayers on the glass was evaluated and scratch thickness for 1000 g sinker was measured ~150 nm. The self-cleaning properties were tested in dry condition (RH<15%) under UV irradiation by evaluating the oleic acid photodegradation and monitoring the hydrophilic properties of the surface with a contact angle measurement. The result showed that contact angle of the layer decreases from 77 to 42° after 25 h UV irradiation. Fourier-transform infrared spectroscopy- Attenuated total reflectance (FTIR-ATR) showed the elimination of C=O bonds of oleic acid on the surface after UV light irradiation. Water droplet contact angle measurement on TiO2 nano-layer exhibited a less hydrophilicity after UV irradiation and the contact angle changed from 15 to 40°, which may be due to the low atmospheric humidity. Adding SiO2 nanoparticles increases roughness of the nano-layer, from 5 to 19 nm, without a significant effect on the photodegradation rate of oleic acid.