Effect of the structure on biological and photocatalytic activity of transparent titania thin-film coatings

Abstract

In this work, the effect of titanium dioxide (TiO 2 ) thin film microstructure on photocatalytic and biological activity was described. The films were prepared by low-pressure and high-energy magnetron sputtering processes. The structural investigations performed by X-ray diffraction revealed that the films from both the processes were nanocrystalline. It was found that TiO 2 prepared by low-pressure process had the anatase structure with crystallites in size of 20 nm, while the film deposited in high-energy process had the rutile form with crystallites in size of 5 nm. The analysis of surface topography with the aid of optical profiler showed that all prepared films were homogenous and their roughness was lower than 1 nm. The wettability studies revealed hydrophilic nature of both films. The values of water contact angle obtained for anatase and rutile films were equal to 40°and 49°, respectively. Both types of the thin films were photocatalitycally active, but rutile exhibited higher decomposition rate as compared to anatase. During the photocatalytic reaction in the presence of TiO 2 -rutile film after 12 hours of UV-Vis irradiation 30 % of phenol was decomposed, whereas in case of TiO 2 -anatase it was only 10 %. Moreover, the influence of as-deposited coatings on the growth of selected microbes (Staphylococcus aureus, Escherichia coli, Candida albicans) was examined. It was found that the structural properties of TiO 2 had an effect on biological activity of these films.

Nanogap-Rich TiO2 Film for 2000-Fold Field Enhancement with High Reproducibility

“… and are the electric and magnetic components, respectively, which are expressed as where and are the Riccati–Bessel functions, and are their first differentiations, and x = 2π n m R /λ and m = ( n + i k )/ n m , where n is the real part of the refractive index of a particle, R is the radius of the particle, k is the imaginary part of the refractive index of the TiO 2 particle, λ is the excitation wavelength, and n m is the refractive index of the medium around the particle (methanol). For these calculations, the refractive index of TiO 2 (rutile) at an excitation wavelength of 632.8 nm was used, with n = 2.65 as the real part and κ = 0.0074 as the imaginary part . The refractive index for the surrounding medium (methanol) was determined to be n = 1.33.…”

The Role of HiPIMS Pulse Length in Reactive Deposition of Transparent Conductive Oxide Nb:TiO2 Films

“…The transmittance in the infrared range (around 800 nm) drops from ≈ 90% (non-coated sample) to ≈ 65% (Nb:TiO 2 coated samples). The transmittance of Nb:TiO 2 coated samples is also about 20% lower than glass coated with non-doped TiO 2 films (anatase phase), when compared with values from the literature 18 . Hence, Nb:TiO 2 films are also a potential candidate for heat-filtering applications.…”

Transparent and Self‐Cleaning Surfaces Based on Nanocomposite Sol‐Gel Coatings

“…This is due to the absorption of TiO 2 on the glass surface which has a bandgap energy of 3.2 eV. [11,34] Comparing the two sets of UV-VIS spectra in Figure 5, it can be seen that Rw4.6@500 absorbs more UV light than other coatings. This property also confirmed by photocatalytic degradation results (Section photocatalytic study), meaning that Rw4.6@500 has higher photocatalytic activity in comparison with Rw4.6@400 and Rw4.6@300.…”