Nanoparticles of very small size (below 10 nm) of TiO<sub>2</sub> material are nowadays the functional building blocks of many developing energy-related technological applications. Nano is clearly different from bulk or extended systems as regards surface area, molecular binding properties, charge separation efficiency, electron/hole transport, photochemical conversion properties, etc. In this work, we investigate the life path of energy (excitons) and charge (electrons and holes) carriers in anatase TiO<sub>2</sub> nanoparticles of different size (2-3 nm) and shape (faceted vs spherical), by means of a wide set of hybrid density functional theory calculations. The attention is focused on the exciton/charge carriers formation, separation, recombination, self-trapping processes, which are analyzed in terms of structural deformations, energy gain or cost, charge localization/delocalization and electronic transitions involved. The computational models are corroborated by an extensive comparison with available experimental data based on photoluminescence measurements, electron paramagnetic resonance and transient absorption spectroscopies. Peculiar differences are observed for spherical nanoparticles with respect to faceted ones because of the higher disorder and larger diversity of coordination sites present on the surface, due also to the presence of hydroxyl groups.

Photoexcited carriers recombination and trapping in spherical vs faceted TiO2 nanoparticles

253rd National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.