Theoretical analysis of band alignment and charge carriers migration in mixed-phase TiO2 systems

CABEZA, GABRIELA F.; MORGADE, CECILIA I. N.; CASTELLANI, NORBERTO J.

Journal of Computational Electronics

Springer

Lugar: Luxemburgo; Año: 2018 vol. 17 p. 1505 - 1514

1569-8025

Photocatalysts based on mixtures of rutile and anataseforms of titania usually show a better catalytic performance than eachindividual component. In order to understand this behavior several experimentaland theoretical approaches have been proposed in the past, looking for anadequate reference frame for aligning energy bands, and arriving sometimes toopposite results. In this work, the theoretical results obtained for the bandalignment applying a modified common anion rule for different possibilities of mixed phase (anatase-rutile) interaction are presented.According to our results, mixedphase systems involve the transfer of electrons from rutile to anatase andholes from anatase to rutile. This analysis would be applicable to real samplesof mixed phase of titania with large particle size. However, for heterogeneoussize particulate systems, it is not only necessary to consider the alignment ofbands of the bulk system, but also those of the corresponding surfaces. In keepingwith the analysis performed, the best mixed systems are those composed by largeparticles of both polymorphs or by small particles of anatase dissolved inrutile. Our results could explain the disagreement found in the literatureregarding the experimental works.