Optimum design of reactive sputtering parameters on the mechanical property of C-doped TiO2 photocatalytic films: CO2 as carbon source

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