Theoretical Analysis of Photo- and Electrochemical Properties of Anatase Nano-Particles

Abstract

Oxide nanoparticles, like TiO2 nanoparticles are often applied in electrodes and photocatalytic systems. We studied the electronic states around the bandgap in anatase-type TiO2 nanoparticles of different shapes with (101) and (001) facets using Density Functional based Tight Binding (DFTB) method. Previous calculation has already shown that most orbitals of the valence and conduction bands forms delocalized band-like orbitals, however there are a significant number localized states at the lower at edge of conduction band, too.The energy and position of these unoccupied localized orbitals can be controlled by the shape of the nanoparticle and these orbitals can play important contribution to both electrochemical and photochemical properties. TD-DFTB calculations showed that the optical spectrum around the band gap is dominated by few transition with large oscillator strength (see Figure), while most of the transitions give only a weak contribution. Figure 1