Polyaniline-sensitized SiO2/TiO2 photocatalysts for the degradation of visible light

In this research, the surface modification has been studied as alternative to improve the photocatalytic properties of the materials. The principal novelty of the core/shell synthesis was the in situ oxidation of the monomer aniline in polyaniline over the TiO2 surface, it gives an increase in the electron transport to enhance the photocatalytic activity of the SiO2/TiO2 system. Thus, the step by step synthesis allow us to modify the superficial porosity of the SiO2 cores for the further formation of the titanium dioxide shell, the resulting surface of the material was modified with different amounts of a conductive polymer polyaniline. The results indicate a successfully coverage by the titanium dioxide in the anatase phase (XRD), the extent of the coverage was confirmed by the FESEM and HRTEM images, it is clear the effect of the methodology on the porosity of the cores, with the highest porosity the more successfully covering, this also indicates an increased specific area creating more available sites for the reactive species formation for the photodegradation. The energy band gap of covered core/ shell materials do not present significant modifications compared with pure anatase TiO2 indicating that the photoactivity of the materials occurs by the electron conduction by the pi-polaron transitions of polyaniline deposited on the surface of titanium dioxide. The photodegradation results indicate the possibility use of the materials for the of aromatic compounds decompositions under visible irradiation.

Automated summary

Surface modification was studied to improve the photocatalytic properties of materials. The core/shell synthesis involved in situ oxidation of aniline over the TiO2 surface, enhancing the photocatalytic activity. The step by step synthesis allowed for modification of superficial porosity and successful coverage by titanium dioxide in the anatase phase. The energy band gap of covered materials remained unchanged compared to pure anatase TiO2, indicating that photoactivity occurs through electron conduction by polyaniline.