Multifunctional TiO2/FexOy/Ag based nanocrystalline heterostructures for photocatalytic degradation of a recalcitrant pollutant

The photocatalytic degradation of pollutants is a key technological application for nanomaterials. Our work aims at developing a multifunctional nanocrystalline heterostructure based on TiO2nanorods, FexOyand Ag nanoparticles (NPs), TiO2NRs/FexOy/Ag, integrating in one nanostructure a visible light photoactive moiety (TiO2NRs/Ag) and a magnetic domain (FexOy), in order to address the photoactivity under visible light and the possibility of recovery and reuse the photocatalyst. The synthesis was carried by preparing first the TiO2NRs/FexOybased heterostructure and then growing Ag NPs with control on size. The resulting multidomain structures were characterized by FTIR and absorption spectroscopy, TEM and SEM microscopy, EDS and XRD analysis. The influence of the Ag NP domain and of its size on the photoactivity of the TiO2NRs/FexOy/Ag nanostructures under visible light were investigated in the photocatalytic degradation of the Nalidixic Acid, an antibiotic used as a model compound representative of recalcitrant pollutants. In the presence of the Ag domain a significant increase of the photoactivity with respect to TiO2NRs/FexOyheterostructures and to the commercially available TiO2P25 was observed. Such an enhanced photocatalytic efficiency was found dependent on the size of the Ag domain and explained taking into account the plasmonic properties and the different possible photoactivation mechanisms.