Heat treatment and substrate dependant properties of titania thin films with high copper loading

Abstract

Copper-doped titania thin films have been prepared on SiO 2 / Si(100), fused-silica and soda-lime glass substrates by using sol-gel deposition and subsequent annealing in air atmosphere at 200-900 8C. Several experimental techniques [X-ray photoelectron spectroscopy (XPS), wavelength dispersive X-ray fluorescence (WDXRF), Raman spectroscopy, atomic force microscopy (AFM), UV-Vis spectroscopy, energy dispersive X-ray analysis (EDX), photocatalytic activity measurements and hydrophilicity measurements] have been applied to characterize these films. The results demonstrate that the films prepared on SiO 2 /Si(100) and fused-silica substrates start to crystallize after annealing above 300 8C, then anatase phase is formed. At 700 8C anatase content starts to decrease and from 800 8C the films consist of rutile. Annealing causes a formation of regions with increased Cu concentration, in case of titania films prepared on SiO 2 /Si(100) substrates. On the other hand films prepared on soda-lime glass substrates show large sodium diffusion into the films, the crystalline nature of the films decreases during annealing and outward segregation of copper compounds does not occur. However the surface of copperdoped titania films on soda-lime glass appear to be naturally hydrophilic (i.e. surface is hydrophilic without UV irradiation), water droplet contact angles as low as 4.28 were achieved. Influence of annealing time and copper-doping to the photocatalytic activity of thin titania films was also studied by using two organic dyes as model contaminants.

Photocatalytic Properties of Titanium Dioxide Thin Films Doped with Noble Metals (Ag, Au, Pd, and Pt)

“…Raman spectra of pure and doped TiO 2 films (Figure ) show a sharp peak at 143 cm −1 ( E g (1)), a weak peak at 197 cm −1 ( E g (2)), and three medium intensity peaks at 397 cm −1 ( B 1g (1)), 516 cm −1 ( A 1g + B 1g (2)), and 638 cm −1 ( E g (3)) which are characteristic of the anatase phase. These values are in agreement with those reported by Joost et al The anatase phase was also observed in the XRD data, shown above. The intense low frequency peak at 143 cm −1 is due to O–Ti–O bending vibrations .…”

Investigation of the structural and optical properties of copper-titanium oxide thin films produced by changing the amount of copper

“…A significant decrease in film thickness is observed with the addition of copper. This is probably due to the increase in crystallinity and grain size of the film, as can be also seen from the XRD and AFM results [25,26].…”

“…Pure TiO 2 and Copper-Titanium oxide thin films are deposited on clean glass substrates by sol-gel dip coating method using titanium tetraisopropoxide and copper (II) acetate as starting precursors. The amount of Cu in the solution is adjusted to be 0, 12.5 wt%, 25 4 , Merck] is incorporated into the solution. In the final step, 1 ml trietilamine [(C 2 H 5 ) 3 N, Merck] is incorporated into the solution and the final solution is mixed for 2 h on the magnetic stirrer.…”

Photocatalytic antibacterial activity of nano-TiO2 (anatase)-based thin films: Effects on Escherichia coli cells and fatty acids

“…Antibacterial applications of TiO 2 often use thin film coatings that can be deposited by various methods including sputtering [17], chemical solution deposition [18], pulsed laser deposition [19] or sol-gel method [20][21][22][23].…”