In
the present research gold and platinum nanoparticles were deposited
simultaneously on three different commercial titania photocatalysts
(Evonik Aeroxide P25, Aldrich rutile, and Aldrich anatase). For the
synthesis of the composites two noble metal reduction methods (in
situ and impregnation) and three noble metal deposition routes (i.e.,
by changing their deposition order, Au/Pt, Pt/Au, and Au–Pt
simultaneously) were used. The photocatalytic performances of the
nanocomposites were evaluated under UV irradiation, through degradation
of oxalic acid and photocatalytic hydrogen production. The best performing
photocatalyst was obtained by sequential noble metal deposition (first
Au followed by Pt) on Evonik Aeroxide P25. The morphological and structural
properties were studied/investigated by using DRS, TEM, HRTEM, EDX,
and XRD. The gold and platinum nanoparticles formed clusters in most
of the cases. Furthermore, the ecotoxicity of the composites was investigated
using Lemna minor growth inhibition tests using static
“lake” approach completed by DLS and ROS indirect measurements.
The toxic effect of the composites which showed the highest photocatalytic
activity did not differ from that of their commercial counterparts,
showing that these nanoparticles were eco-friendly. This result shows
the great capacity of these materials to be used in the next future
in photocatalytic applications.
In the present work, copper nanoparticles were deposited onto the surface of two different commercial titanias (Evonik Aeroxide P25 and Aldrich anatase). During the synthesis, the concentration of copper was systematically varied (0.5%, 1.0%, 1.5%, 5.0%, and 10 wt.%) to optimize the composite-composition. The photocatalytic activity was evaluated under UV-light, using methyl orange and Rhodamine B as model and ketoprofen as real pollutant. For the hydrogen production capacity, oxalic acid was used as the sacrificial agent. The morpho-structural properties were investigated by using XRD (X-ray diffraction), TEM (Transmission Electron Microscopy) DRS (Diffuse Reflectance Spectroscopy), XPS (X-ray Photoelectron Spectroscopy), and SEM-EDX methods (Scanning Electron Microscopy-Energy Dispersive X-ray Analysis). Increasing the copper concentration enhanced the photocatalytic activity for methyl orange degradation in the case of Aldrich anatase-based composites. When the P25-based composites were considered, there was no correlation between the Cu concentration and the activity; but, independently of the base photocatalyst, the composites containing 10% Cu were the best performing materials. Contrarily, for the ketoprofen degradation, increasing the copper concentration deteriorated the photoactivity. For both Aldrich anatase and P25, the best photocatalytic activity was shown by the composites containing 0.5% Cu. For the degradation of Rhodamine B solution, 1.5% of copper nanoparticles was the most suitable. When the hydrogen production capacity was evaluated, the P25-based composites showed higher performance (produced more hydrogen) than the Aldrich anatase-based ones. It was found that Cu was present in four different forms, including belloite (Cu(OH)Cl), metallic Cu, and presumably amorphous Cu(I)- and Cu(II)-based compounds, which were easily convertible among themselves during the photocatalytic processes.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.