Bottom up anatase monodisperse nanoparticles grown on sepiolite showing high thermal stability and optimal optical properties for self-cleaning applications

Powder samples of anatase monodisperse nanoparticles (np's) have been in-situ synthesized from sepiolite microparticles doped with TiIV. The role of this clay is double, by one hand, it acts as a chemical reactor, and on the other hand, it becomes a solid substrate for particles, which pin them up avoiding Ostwald ripening process on heating. In this work we show the high thermal stability of these metastable anatase particles up to 850C, around 200C above the anatase/rutile transformation for ordinary powder particles. Relevant information about the band-gap structure has been obtained both, by optical diffuse reflectance and emission spectroscopy, which revealed the nature of photon absorption and recombination around the band-gap which determine the utility of this materials as a self-cleaning agent for solid materials. [Display omitted] •Synthesis of functionalized anatase nanoparticles in microporous sepiolite.•Sepiolite thermally stabilized anatase up to 900 °C b.•Optical characterization of band transition in anatase nanoparticles by excitation spectroscopy.•Correlation between excitation spectroscopy and optimal energy irradiation for photocatalysis.•UV driven self-cleaning.