Ni Underlayer Effect for the Structure Development and Visible Light Photocatalytic Efficiency of Carbon-Doped TiO2 Film

Photocatalytic treatment of contaminated aqueous solutions makes use of the specific interaction between photocatalysts and ultra-violet or visible light irradiation. This method belongs to the wider class of Advanced Oxidation Processes that generates reactive oxygen species (peroxides, superoxide, hydroxyl radical, singlet oxygen, etc.) and uses them for the non-selective oxidation of various organic and inorganic compounds. In THE current study magnetron sputtering technique was used to deposit carbon-doped TiO2 films which are known to have significant photocatalytic activity in the visible light spectra and can be used for the neutralisation of contaminated solutions. Structural properties of the as-deposited films were analysed by XRD, XPS and AFM techniques, whereas their visible light photocatalytic activity was estimated by analysing Rhodamine B solution bleaching kinetics. When carbon-doped TiO2 photocatalysts were formed on borosilicate glass XRD analysis showed that they consisted of mixed phase (rutile-anatase) TiO2 where both phases contributed by similar parts. However, when the same deposition procedure was used to deposit carbon-doped TiO2 films on glass covered by Ni layer, formation of metastable anatase phase was enhanced. Estimation of visible light photocatalytic activity of the films revealed that Ni underlayer had positive effect for the efficiency of Rhodamine B solution bleaching and it could be beneficial for the practical wastewater treatment systems. It was suggested that observed improvement was mainly achieved due to the structural changes of TiO2 crystal phase, but other mechanisms like prevention of impurity diffusion from the glass substrate to the carbon-doped TiO2 film, or positive Ni doping effect could not be excluded completely.