Optimum Design of Reactive Sputtering Parameters on the Mechanical Property of C-Doped TiO₂ Photocatalytic Films: CO₂ as Carbon Source

Abstract

In this research, CO2 gas was used as carbon and oxygen source to prepare carbon-doped TiO2 (C-TiO2) films on stainless steel by reactive magnetron sputtering. In order to grasp the relationship between sputtering process, microstructure and mechanical and photocatalysis properties of C-TiO2 thin film, a orthogonal experiment design validated by following mechanical analysis and photo-degradation experiments was employed to determine the optimal reactive sputtering parameters, including substrate temperature, sputtering power and CO2 gas flow rate. nanoindentation and nanoscratch tests were employed to analyze the hardness, modules and adhesion strength of as-deposited C-TiO2 films, respectively. Taking the hardness, modules and adhesion between the film and the substrate as a reference of integrated mechanical properties, range analysis of as-prepared C:Ti-O films were done to search the optimal combination of sputtering parameters. The photocatalytic activities of as-prepared C-TiO2 films using methyl orange (MO) as colored dye indicator were also evaluated by measuring absorbance and calculating the MO’s decolorization rate under different UV light irradiation time. The results of photocatalysis experiment compared with a blank group proved that C-TiO2 films sputtered at the optimized reactive sputtering parameters can achieve both superior photocatalysis and mechanical properties.

Effect of the incorporation of carbon in the structure of TiO2 anodized with HCl on the mechanical and tribological properties

“…It can be noted in Table 2 that the carbon-incorporated TiO 2 samples presented hardness values above that of the titanium sheet and the unincorporated sample. These results are not related in a reciprocal way with the amount of carbon found by EDS, but it has been observed that in other works that the set of carbon and TiO 2 deposited by sputtering is presented in the same way in variability in the values of both hardness as Young's modulus [22]. Annealing the anodized TiO 2 at temperatures close to 500 °C results in a decrease in hardness and elastic modulus due to a change in crystallinity [23,24], but it is thanks to the carbon that the oxide capacity was optimized.…”

Structure and phase composition study of thin TiO2:C films deposited by r.f. magnetron sputtering

“…Thin films of TiO2 are deposited very often by magnetron sputtering (radiofrequency (rf) or direct current (dc)) [7] due to the high reproducibility of the deposited films quality. Two main ways for introducing the carbon dopant are used: from a gas mixture of CO (or CO2) combined with Ar in different ratios [8,9], which results in low levels of C doping (0.1 -1 at % carbon); or by co-sputtering of a target of TiO2 and carbon plates placed on the target [10], as it is expected that the use of the latter path will result in a larger doping values of carbon, i.e. shifting of the absorption edge to the visible region.…”