Morphology-Dependent Correlation Between Photoluminescence and Photocatalytic Activity of Anatase– Titania Photocatalyst

Abstract

Nanocrystalline particles and nanotubes of anatase–titania photocatalyst have been processed via sol–gel and hydrothermal methods, and subsequently surface-modified by depositing silver/ silver oxide via ultraviolet-reduction technique. The samples have been characterized using different analytical techniques for determining their morphology, structure, specific surface-area, moisture-adsorption, photoabsorption, and photoluminescence. The photocatalytic activity, under the ultraviolet-radiation exposure, has been measured in an aqueous solution using the methylene blue as a model catalytic dye-agent and is compared with the photoluminescence intensity variations in air under different processing conditions for the two different morphologies of anatase–titania photocatalyst. It has been demonstrated that the conventional correlation between the photoluminescence and photocatalytic activity is highly morphology-dependent and is not obeyed by the nanotubes of anatase–titania. This has been primarily attributed to the change in the mechanism of photo-induced electron trapping in air and aqueous media, which controls the variation in the PL intensity and photocatalytic activity, as typically observed here for the pure and silver-deposited nanotubes of anatase–titania.