Wettability and photocatalysis of CF4 plasma etched titania films of honeycomb structure

We prepared titania films by aerosol deposition (AD), in which titania powder is supersonically accelerated for deposition onto a substrate. These AD titania films exhibited hydrophilicity and photocatalysis under UV exposure. However, after surface modification by CF4 plasma-etching, the films showed higher hydrophilicity and lower photocatalytic effect. After sufficient modification, they exhibited superhydrophilicity, which was induced by the presence of fluorine. This type of surface modification is useful for promoting hydrophilicity under no UV light exposure.