Using DFTB to Model Photocatalytic Anatase-Rutile TiO$_2$ Nanocrystalline Interfaces and their Band Alignment

TL;DR

This paper develops a new DFTB parameter set to accurately model quantum confinement in TiO2 nanocrystals, revealing how interface geometry influences band alignment and enhances photocatalytic efficiency.

Contribution

The study introduces a novel DFTB parameter set enabling detailed analysis of interface geometry effects on band alignment in TiO2 nanocrystals.

Findings

Interface structure significantly affects band alignment.

New DFTB parameters accurately model quantum confinement.

Enhanced understanding of photocatalytic mechanisms.

Abstract

Band alignment effects of anatase and rutile nanocrystals in TiO$_2$ powders lead to an electron hole separation, increasing the photo catalytic efficiency of these powders. While size effects and types of possible alignments have been extensively studied, the effect of interface geometries of bonded nanocrystal structures on the alignment is poorly understood. In order to allow conclusive studies of a vast variety of bonded systems in different orientations, we have developed a new density functional tight binding parameter set to properly describe quantum confinement in nanocrystals. Applying this set we found a quantitative influence of the interface structure on the band alignment.