Photocatalytic Characteristics of TiO₂ Films Deposited by Oxygen Plasma-Assisted Reactive Evaporation Method

Abstract

Titanium dioxide (TiO2) films were deposited by the oxygen plasma-assisted reactive evaporation (OPARE) method. TiO2 films with an anatase structure were formed when activated oxygen plasma was supplied to the substrate during deposition, whereas the films with a rutile structure were formed when nonactivated oxygen gas was supplied. These results were explained by the promotion of the oxidization of titanium atoms by the supply of activated oxygen plasma, because the anatase film is obtained under conditions where sufficient oxidization of titanium atoms is achieved, and the rutile film is formed under the conditions where insufficient oxidization occurs. These results indicate that oxygen plasma assist is an effective method for promoting oxidization and reducing the amount of oxygen gas used in this method. Both films deposited with or without plasma assist at temperatures greater than 250 °C exhibited ultra-hydrophilicity. These films also showed definition methylene-blue (MB) decomposition photocatalytic performance indexes in the range from 7.8–11.9 µmol·l-1·min-1. The described results indicate that the TiO2 films obtained by this method exhibit adequate performance for photocatalytic applications.