Optimum design of reactive sputtering parameters on the mechanical and photocatalytic properties of C-doped TiO2 films

TiO2 is widely studied for its good photocatalysis activity. In this research, CO2 gas was used as carbon and oxygen source to prepare carbon-doped TiO2 (C-TiO2) films on stainless steel using reactive magnetron sputtering. In order to grasp the relationship between sputtering process, microstructure and mechanical and photocatalysis properties of C-TiO2 thin film, orthogonal experiment design combining related mechanical analysis and photo-degradation experiment was employed to find a set of optimal reactive sputtering parameters, including substrate temperature, sputtering power and CO2 gas flow rate. Nano-indentation and nano-scratch tests were employed to analyze the hardness, modules and adhesion strength of as-deposited C-TiO2 films, respectively. Taking hardness, modules and adhesion between the film and 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 result of photocatalysis experiment compared with a blank group proved that at the optimized reactive sputtering condition C-TiO2 films can achieve both good photocatalysis and mechanical property