Antimicrobial efficacy of photocatalytic TiO2 coatings prepared by arc ion plating

Photocatalytic titanium dioxide films have been extensively studied for possible antimicrobial application with however real-time substrate heating or post annealing required for currently available thin film deposition processes. This research involves an arc ion plating method to produce TiO2 films on medical grade AISI 304 stainless steel at low temperature. Photocatalytic performance of the deposited specimens is tested with methylene blue solution, and antimicrobial efficacy is evaluated through the use of JIS Z2801:2000 industrial standard for better understanding the relation between photocatalytic effect and antimicrobial efficacy. The result shows that columnar TiO2 film with an anatase phase structure can be prepared successfully within a proper coating parameter range. By increasing deposition time, the film initially consists of mainly rutile phase followed by anatase phase at later stage and reaches its ultimate photocatalytic efficiency while its antimicrobial activity (R) reaches a maximum value. On the other hand, oxygen partial pressure as the coating parameter favors the film crystallinity and anatase phase formation. As a result, its photocatalytic efficiency of the deposited film reaches maximum as well as antimicrobial activity of the deposited film when oxygen partial pressure is increased. Photocatalytic efficiency and antimicrobial activity of deposited TiO2 film are thus dominantly determined by the presence of anatase phase.