Fabrication and cavity-size-dependent photocatalytic property of TiO2 hollow nanoparticles with tunable cavity size

[Display omitted] •The tunable cavity size of TiO2 hollow nanoparticles was enlarged from 1−3 nm to 7−9 nm.•The TiO2 hollow nanoparticles exhibit unique cavity-size-dependent properties on UV absorption and photocatalytic activity.•For anatase and rutile mixture phases and pure anatase phase, the rules of the cavity size dependent properties are different. TiO2 hollow nanoparticles with tunable cavity size were prepared via a microwave-assisted hydrolysis reaction between TiCl4 and different amounts of HF aqueous solution, followed by calcination at 400 °C for 2 h. The obtained TiO2 hollow nanoparticles with tunable cavity size were characterized with TEM, SEM, XRD, Raman, BET, UV–vis absorption spectra, and photocurrent measurement. It was found that the tunable cavity size of TiO2 hollow nanoparticles was apparently enlarged from 1 to 3 nm to 7–9 nm by increasing the content of HF, and that HF also plays a crucial role in the crystallization of TiO2. The TiO2 hollow nanoparticles exhibit the unique cavity-size-dependent properties of UV absorption and photocatalytic activity for acetone degradation. This study offers a novel approach to fabricating TiO2 hollow nanoparticles with tunable cavity size, and the unique cavity-size-dependent photocatalytic property has potential for wide popularization and application prospects.