Synthesis and photocatalytic characterisation of mesoporous TiO2 films doped with Ca, W and N

AbstractMesoporous TiO2 films doped with Ca2+, W6+ and nitrogen were obtained by sol-gel method using dip-coating procedure onto glass-slides in order to study the influence of dopants in their textural properties and photocatalytic activity. Titania sols were synthesized with and without dopants using titanium isopropoxide as titanium precursor, two complexing agents, acetic acid and acetyl acetone, and two pore generating agents, Pluronic F-127 (F127) and polyethylene glycol hexadecyl ether (Brij58). Films were characterised by Fourier Transform Infrared Spectroscopy (FTIR), Grazing X-ray diffraction (GXRD) and Transmission Electron Microscopy (TEM). Environmental Ellipsometric Porosimetry (EEP) permitted to obtain the adsorption/desorption isotherms and total pore volume, and to determine the porous size distribution and specific surface area (Ss) of the films. The photocatalytic activity was evaluated through the degradation of methyl orange (MO) in aqueous solution under UV light exposure. The photocatalytic activity depends on the nature of dopants, which affect the TiO2-anatase crystallite size and the textural properties of the final material. The best results of MO degradation were obtained for the films doped with Ca2+, this being correlated with the pore size and specific surface area of the films besides the dopant-effect on the photocatalytic mechanisms