Photocatalytic activity of dye-sensitized and non-sensitized GO-TiO2 nanocomposites under simulated and direct sunlight

Abstract

Graphene oxide (GO), amine-modified graphene oxide (mGO), and N-TiO2 composites were synthesized by low-temperature hydrothermal method and characterized by using X-ray diffraction, X-ray photoelectron spectroscopy, FTIR, and BET analysis techniques. The films of synthesized TiO2, mGO:TiO2, N-TiO2, GO:TiO2, GO:N-TiO2, and commercially available P25 were prepared by doctor blade method. These films and their perylene-3,4,9,10-tetracarboxy tetrabutylester (PTE)-sensitized forms were employed as photocatalysts for the photodegradation of rhodamine-B (RhB) under Xe lamp and direct sunlight irradiations. Independent from the irradiation source, the photocatalytic order of the non-sensitized films were GO:N-TiO2 > GO:TiO2 > N-TiO2 > mGO:TiO2 > TiO2 > P25, but seven and 15 folds of increments were detected under direct sunlight irradiation. PTE-sensitized catalyst films exhibited more than two folds of increase in the photocatalytic rate constants compared to their non-sensitized counterparts under Xe lamp irradiation. Under direct sunlight irradiation no matter which photocatalyst was used, the photocatalytic activity of these films was enhanced seven folds. Reusability tests revealed no significant changes in the photocatalytic rate constants obtained with both the non-sensitized and sensitized films.