Enhanced Photocurrent Response of Titania-Nanotube Heterojunction Devices Capped with Titanium Disilicide

Abstract

The coating of titania nanotubes to enhance their photocurrent response is presented. Electrochemically anodized titania nanotubes were capped by coating a 25 nm layer of titanium disilicide using the radio frequency (RF) magnetron sputtering technique. The optical properties of titania nanotubes were unchanged as a result of coating, but the titanium disilicide acted as an enhanced charge-transfer barrier, which reduced the electron–hole recombination on the surface of the titania nanotubes. A considerable increase in the photocurrent density was observed for the coated titania nanotubes resulting from the enhanced charge-transfer process. As both the electrochemical anodization and RF magnetron sputtering technique are highly scalable, the composite device could be useful in designing cheaper photoanodes for energy applications, as well as environmental applications such as water purification.