Abstract
In the present work, ternary composites were synthesized from commercial titanias (Evonik Aeroxide P25, Aldrich anatase—AA and Aldrich rutile—AR) and two noble metals (gold and platinum). This research focuses on the composition of the photocatalysts, especially on the noble metals. The ratio between the noble metals varies from 0.25 to 0.75% in each composite for each noble metal. Transmission electron microscopy (TEM), X-ray diffraction (XRD) and diffuse reflectance spectroscopy (DRS) measurements were carried out to investigate the structural and optical properties. From the TEM, it can be observed that the particle sizes of the noble metals were between 1 and 4 nm, while the (anatase and rutile) crystals of P25 were 20–40 nm. The XRD showed that the semiconductors’ composition remained unchanged during/after the deposition of noble metal nanoparticles. By the DRS measurements, using the Kubelka–Munk equation, it can be concluded that the deposition of the noble metal nanoparticles resulted the decrease of the bandgap energies of the titanias. The photocatalytic activity was investigated under the irradiation of UV light. Oxalic acid and salicylic acid were used as model pollutants. The hydrogen production capacity was investigated as well, where the sacrificial agent was oxalic acid, and UV irradiation was used.
Highlights
Materials at nanometer scale show different chemical and physical properties than their macroscopic forms, which are advantageous for many current research fields
The following materials were used without further purification: Evonik Aeroxide P25 (89 wt% anatase, 11 wt% rutile; 99.5% trace metal basis; 25–40 nm primary particle size and 25 m2/g specific surface area, Essen, Germany), Aldrich anatase (99.7% trace metal basis; 80 nm primary particle size and 9.7 m2/g specific surface area, Schnelldorf, Germany) and Aldrich Rutile (99.995% trace metals basis; 150–200 nm primary particle size and 2.9 m2/g specific surface area, Schnelldorf, Germany)—will be henceforward denoted as P25, AA and Aldrich rutile (AR), respectively
It must be mentioned that the noble metal nanoparticles were not detectible, as their concentration was lower than the detection limit of the instrument and some of the most intensive diffraction peaks (e.g., the one at 38 (2θ degrees) for Au, JCPDS card no. 01-1174) were covered by the triplet signal of anatase in the same region
Summary
Materials at nanometer scale show different chemical and physical properties than their macroscopic forms, which are advantageous for many current research fields. Among the nanoscaled semiconductor materials (Cu2O [9], WO3 [10], ZnO [11], BiOX [12], etc.) titania photocatalysts are the most studied ones [13]. The efficiency of these semiconductors can be enhanced by creating composites [14]. These nanostructures, containing semiconductors and metal nanoparticles, were synthesized and used so far. It was found that the composition of the composites had a major effect on the overall photocatalytic efficiency [15]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
