PREPARATION OF NANOSTRUCTURED TIO2 IN THE GREEN UP PROJECT

GREEN UP aims to develop a new generation of photon upconversion hybrid nanomaterials, utilizing triplet-triplet annihilation for solar photocatalysis and nanostructured TiO2 as the support/receiver material. Mechanical processing of powders represents a convenient route to the solvent-free preparation of nanostructured TiO2, provided that transformation kinetics is suitably characterized, and mechanical activation is properly controlled. This is the subject of the present contribution. We investigate the transformation kinetics of TiO2 powders that undergo mechanical processing by ball milling under various experimental conditions. To this aim, we use different ball mills and systematically change processing and experimental variables. Phase transformations are studied by X-ray diffraction. In agreement with literature, we observe the gradual transformation of starting anatase in an intermediate phase, first, and then, in rutile. Grain size reduction of anatase is faster than its transformation. The intermediate and final TiO2 phases form invariably exhibit nanocrystallinity. We show that the transformation rates correlate with several processing and experimental variables. This study was carried out within the «GREEN UP: GREENER NANOMATERIALS FOR UPCONVERSION IN PHOTOCATALYTIC APPLICATIONS» project – funded by the Ministero dell’Università e della Ricerca – within the PRIN 2022 program (D.D.104 -02/02/2022) funded by the European Union - Next Generation EU. This manuscript reflects only the authors’ views and opinions, and the Ministry cannot be considered responsible for them.