Semiempirical computational study of oxygen vacancies in a decahedral anatase nanoparticle

Abstract

Formation of oxygen vacancies (VO) is an important step of many catalytic reactions following the Mars van Krevelen mechanism. High rate of oxidation is associated with low energy of VO formation while high selectivity requires an optimal energy of VO formation. In the present computational study, enthalpy of VO formation (ΔHOVF) is studied in a decahedral anatase nanoparticle (TiO2)121(H2O)6 using PM6 method. ΔHOVF shows large variations for oxygen atoms in different locations on facets, edges and vertices. VO are much more stable in the (101) facet compared to the (001) facet, while internal VO are more stable for (101) but equally stable for (001) facet compared to surface vacancies on average. Comparison with literature DFT methods results reveals good consistency and high computational efficiency of the PM6 method for vacancies formation energy. Pm6 also correctly predicts admixture states of the Ti3+ within the band gap, but absolute values of electronic band gap and position of admixture states is overestimated and needs scaling factors.

Recent Advancements in the Understanding of the Surface Chemistry in TiO2 Photocatalysis

“…Le and Schweigert investigated the interfaces between two decahedral anatase nanoparticles of (TiO 2 ) 70 (H 2 O) 2 connected together via their (001) facets or via (101) facets [21]. They found that the deep trap states could be localized at the interfaces between two nanoparticles due to local structure deformations.…”