Semiempirical computational study of oxygen vacancies in a decahedral anatase nanoparticle

• Published in: International journal of quantum chemistry 2019-03, Vol.119 (5), p.n/a
• Main Authors: Vorontsov, Alexander V., Smirniotis, Panagiotis G.
• Format: Article
• Language: English
• Subjects: Admixtures; Anatase; Apexes; Catalysis; Chemistry; Computing time; Energy gap; Enthalpy; Free energy; Graph theory; Heat of formation; heterogeneous catalysis; molecular modeling; Nanoparticles; Oxidation; Oxygen atoms; photocatalysis; Physical chemistry; quantum dots; Quantum physics; Scaling factors; Selectivity; semiempirical calculations; Titanium dioxide; Vacancies
• ISSN: 0020-7608; 1097-461X
• DOI: 10.1002/qua.25806

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. The formation of oxygen vacancies is an important step of many catalytic reactions following the Mars van Krevelen mechanism. First‐principles calculations are employed to investigate symmetry‐unique oxygen vacancies for a decahedral anatase nanoparticle. Enthalpy of formation, atomic structure, unpaired electrons location and the corresponding admixture states can be theoretically estimated. Most stable vacancies can serve as models for studies on mechanisms of catalytic reactions. Symmetry unique oxygen vacancies were investigated for a decahedral anatase nanoparticle. Enthalpy of formation, atomic structure, unpaired electrons location and the corresponding admixture states are reported. Most stable vacancies can serve as models for studies on mechanisms of catalytic reactions.