Copper NPs Decorated Titania: a Novel Synthesis by High Energy US

Objectives TiO2 is one of the most used semiconductors as photocatalytic material because of its well-known good properties. Nevertheless there is also a need of improvement, especially to increase its activity under visible light1. Among the several modification methods that were developed in order to accelerate the photoconversion and enable the absorption of visible light, the surface deposition of either metal or metal oxide nano-particles (NPs) can be useful because metals onto the TiO2 surface can enhance the electron transfer and/or the charge separation and improve the formation of free hydroxyl radicals; it was shown that also metal oxide particles can have a positive effect because they support charges carriers separation and prevent their recombination2. The use of copper ions as dopants has recently attracted much attention because these species including Cu2O and CuO can serve as electron mediator extending the absorption to the long wavelength region3; Sonochemistry is a novel and interesting way to obtain surface decoration of TiO2 materials with metal nanoparticles4. As very few studies on the photocatalytic performance of Cu nanoparticles (Cu NPs) have been reported so far, different samples of Cu-decorated-TiO2, were tested in this work regarding their photodegradation of VOC’s in gas phase only under visible light only. Methodology and outcomes Samples with different loadings of Copper were prepared with the sonochemical method. The precursor materials were CuCl2*2H2O for copper and micrometric TiO2 (1077 by Kronos); for each synthesis the US power was set at 50 Wcm-2 at a constant bath temperature of 62°C. Each sample was characterized by FT-IR analysis, TEM, XRD, and XPS; moreover, the UV-VIS absorption spectra were calculated with the band gap evaluation. The samples show an increasing of the absorption in the visible wavelengths, proportional to the copper amount; the band gap values are very interesting because it is shown that the TiO2 surface decoration using ultrasounds moves the band gap to lower value. These results are consistent with the photocatalytic tests, in which an increased activity under visible light is reported.