Low density phases of TiO2 by cluster self-assembly

Abstract

Abstract The interest in titanium dioxide (TiO $$_2$$ 2 ) phases is growing due to the number of applications in cosmetics, food industry and photocatalysis, an increase that is driven by its exceptional properties when engineered at the nanoscale like in the form of nanoparticles. Our goal is to discover unknown low-density phases of TiO $$_2$$ 2 , with potential for applications in various fields. We then use well-known TiO $$_2$$ 2 clusters as fundamental building blocks to be self-assembled into unique structures to study their distinct characteristics. Density functional calculations are employed to relax the structures and identify the most stable TiO $$_2$$ 2 structures within an energy range of 0.1 eV per atom from the rutile and anatase phases, which are confirmed, validating our methodology. Going beyond conventional phases, we found two-dimensional TiO $$_2$$ 2 structures, previously explored in separate studies, and showing typical structures of transition metal dichalcogenide layers, that forge a bridge between different TiO $$_2$$ 2 structures. It is noteworthy that our investigation uncovered an entirely novel class of TiO $$_2$$ 2 structures featuring hexagonal cages like beehive channels, opening novel phases with huge potential. These discovered low-density phases are interesting, particularly the hexagonal cage structures with remarkable large gaps, because they introduce other dimensions for uncharted applications in the ever-growing TiO $$_2$$ 2 landscape.