Photocatalytic behaviour of nanocarbon-TiO2 composites and immobilization into hollow fibres

Abstract

Nanocarbon–TiO2 composites were prepared by the liquid phase deposition method using TiO2 and three different nanocarbon materials: carbon nanotubes, fullerenes and graphene oxide. The photocatalytic efficiency of these composites was studied for the degradation of diphenhydramine pharmaceutical and methyl orange azo-dye compounds. The results suggest different synergistic effects between the carbon phase and the TiO2 particles depending on the nature and content of the nanocarbon material employed. Among all the materials tested, the titania composite containing 4 wt.% of graphene oxide exhibited the highest photocatalytic activity under both near-UV/Vis and visible light irradiation, outperforming the synthesized bare TiO2 and the benchmark Evonik P25 TiO2 photocatalyst. The high efficiency of the composite containing graphene oxide was attributed to the optimal assembly between the TiO2 nanoparticles and graphene oxide sheets, making the material to act simultaneously as electron acceptor and donor, thus suppressing charge recombination. Aiming at technological applications, this photocatalyst was immobilized into hollow fibres, showing significant catalytic activity and stability in continuous operation.