Microwave-assisted synthesis of TiO 2 nanoparticles: photocatalytic activity of powders and thin films

Abstract

A simple, rapid, and effective synthesis methodology for the preparation of high-performance TiO₂ nanoparticles and thin films by combining colloidal sol-gel and microwave-assisted hydrothermal synthesis was developed. The obtained results indicate that the heating with microwaves at 180 °C for 20 min was enough to synthesize crystalline TiO₂ nanoparticles, presenting anatase as a major phase with a crystal size of ~ 7 nm and a specific surface area of 220 m² g⁻¹. A secondary thermal treatment improved the crystallinity and induced the anatase-to-rutile transformation. The highest photocatalytic activity was found for the as-synthesized powder without any additional thermal treatment. Thin films were also prepared by dip-coating and its high photocatalytic activity showed a kinetic curve comparable to that of a thin film of commercial TiO₂ powder prepared under similar conditions.

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