DFT study of anatase-derived TiO₂nanosheets/graphene hybrid materials (Phys. Status Solidi B 8/2014)

Abstract

The search for novel materials with photocatalytic applicability is one of the most debated and investigated topics in materials science. In this context, interfaced hybrid systems are considered systems of particular interest. Y. Masuda et al. (pp. 1471–1479) have studied layered systems formed by graphene and TiO2 nanosheets (NSs). A full characterization of “dry” (physisorbed) and "wet" (chemisorbed) models able to mimic the synthetic routes is here performed. For the latter systems, that formally represent graphene oxide (GO)-titania hybrids, the relationship between oxygen amount and electronic/optical properties is investigated. In both physisorbed and chemisorbed models charge transfer between graphene and TiO2 NS is observed, but the chemical bond between graphene and TiO2 NS clearly increases the electronic coupling between the two layered components. The GO/TiO2 chemisorbed system is characterized by a higher photoresponsivity in the visible region due to the raise of the new valence band maximum state that lies in the pristine bandgap of TiO2 NS. Same effect is not observed for physisorbed systems which do not show, at variance, increased photoresponsivity in the visible region.