Tm-doped TiO₂ and Tm₂Ti₂O₇ pyrochlore nanoparticles: enhancing the photocatalytic activity of rutile with a pyrochlore phase

Abstract

SummaryTm-doped TiO2 nanoparticles were synthesized using a water-controlled hydrolysis reaction. Analysis was performed in order to determine the influence of the dopant concentration and annealing temperature on the phase, crystallinity, and electronic and optical properties of the resulting material. Various characterization techniques were utilized such as X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy and UV–vis spectroscopy. For the samples annealed at 773 and 973 K, anatase phase TiO2 was obtained, predominantly internally doped with Tm3+. ICP–AES showed that a doping concentration of up to 5.8 atom % was obtained without reducing the crystallinity of the samples. The presence of Tm3+ was confirmed by X-ray photoelectron spectroscopy and UV–vis spectroscopy: the incorporation of Tm3+ was confirmed by the generation of new absorption bands that could be assigned to Tm3+ transitions. Furthermore, when the samples were annealed at 1173 K, a pyrochlore phase (Tm2Ti2O7) mixed with TiO2 was obtained with a predominant rutile phase. The photodegradation of methylene blue showed that this pyrochlore phase enhanced the photocatalytic activity of the rutile phase.

Synthesis of W‐doped TiO2 by low‐temperature hydrolysis: Effects of annealing temperature and doping content on the surface microstructure and photocatalytic activity

“…These results show clearly that the photocatalytic activity does not depend only on the band gap but the annealing temperature and doping content can play an important role in enhancing the photocatalytic activity. [42,43] Similar results were reported by De los Santos et al [51] This synergistic effect of photocatalytic characteristics was also highlighted by Oseghe et al, [24] for MCPA photocatalytic degradation under W-doped Titania. The new phase W y Ti 1-y O 2 appeared during the preparation of the sample 5W-900 enhancing the photocatalyst activity under visible light.…”

“…Finally, the reactive species, including •OH, •OOH, and 1 O 2 all possess sufcient energy for oxidation of MB (Equation (5)) 5 2.6 2.7 2.8 2.9 3.0 3.1 3.2 3.3 3.4 On the other hand, the adsorption of hydroxyl groups and/or superoxide species onto the surface of the photocatalyst allows them to react with photogenerated holes, which reduces the recombination of the electron-hole pairs and enhances the charge transfer by creation of a new energy level. [42,43] Similar results were reported by De los Santos et al [51] This synergistic effect of photocatalytic characteristics was also highlighted by Oseghe et al, [24] for MCPA photocatalytic degradation under W-doped Titania.…”

Easy Synthesis Method of MoS2/TiO2 Nanostructure with Great Performance of Catalytic Activity Under Visible Light

“…The results from DRX and Raman spectroscopy show that the samples annealed at 700°C had greater crystallinity than those annealed at 500°C. Good crystallinity is very important in photocatalytic activity because it results in better movement of the charge carriers [75]. Further, the recombination between TiO 2 with MoS 2 was favorable thermodynamically, and due to the presence of Mo ions, successful separation of photoexcited electron-hole pairs prolonged the lifetime of photoexcited pairs.…”

Tetrathiafulvalene Scaffold-Based Sensitizer on Hierarchical Porous TiO2: Efficient Light-Harvesting Material for Hydrogen Production

“…Moreover, higher phase crystallinity enhanced the photocatalytic activity. 45 The porous nature of the prepared samples HPT-20-400, HPT-20-500, and HPT-20-800 was analyzed by Brunauer− Emmett−Teller (BET) theory. From the results (Figure 4 and Table S1), we observed that the specific surface area measured by adsorption−desorption isotherms was affected with the increase in the activation temperature of the catalyst.…”