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Titanium dioxide (TiO2) nanoparticles (NPs) are widely used in industry and commercial products. Thus, their potential risks to the environment and human health must be evaluated. Doping NPs with certain ions makes it possible to mix properties or generate new ones. Thus, in order to track TiO2 NPs in biological assays, doping with europium (Eu3+) ions was performed, which luminesce in red. Here, we synthesized TiO2 and Eu3+-doped TiO2 nanocrystals (NCs) in anatase phase to verify the toxicity at different concentrations in Drosophila melanogaster and track the distribution of these NCs in vivo. We verified that the incorporation of europium improved the biocompatibility in relation to the pure samples. The presence of Eu3+-doped TiO2 NCs in the gut, brain, and fat body of larvae and intestinal cells of adult animals was detected. Eu3+-doped TiO2 NCs caused significant larval and pupal mortality rates, in addition to leading to the formation of reactive species, especially at high concentrations. Therefore, our data demonstrated it was possible to trace the Eu3+-doped TiO2 NCs, but TiO2 and Eu3+-doped TiO2 NCs in anatase phase were toxic to fruit flies at the tested concentrations, and should be used with caution to minimize health risks.

The impact of a titania (TiO2) support film surface on the catalytic activity of gold nanoparticles (Au NP) was investigated. Using the reactive dc-magnetron sputtering technique, TiO2 films with an amorphous, anatase, and nitrogen-doped anatase crystal structure were produced for a subsequent role as a support material for Au NP. Raman spectra of these TiO2 films revealed that both vacuum and NH3 annealing treatments promoted amorphous to anatase phase transformation through the presence of a peak in the 513–519 cm−1 spectral regime. Furthermore, annealing under NH3 flux had an associated blue shift and broadening of the Raman active mode at 1430 cm−1, characteristic of an increase in the oxygen vacancies (VO). For a 3 to 15 s sputter deposition time, the Au NP over TiO2 support films were in the 6.7–17.1 nm size range. From X-ray photoelectron spectroscope (XPS) analysis, the absence of any shift in the Au 4f core level peak implied that there was no change in the electronic properties of Au NP. On the other hand, spontaneous hydroxyl (–OH) group adsorption to anatase TiO2 support was instantly detected, the magnitude of which was found to be enhanced upon increasing the Au NP loading. Nitrogen-doped anatase TiO2 supporting Au NP with ~21.8 nm exhibited a greater extent of molecular oxygen adsorption. The adsorption of both –OH and O2 species is believed to take place at the perimeter sites of the Au NP interfacing with the TiO2 film. XPS analyses and discussions about the tentative roles of O2 and –OH adsorbent species toward Au/TiO2 systems corroborate very well with interpretations of density functional theory simulations.

Pure and Cu doped anatase/rutile mixed TiO 2 nanomaterials were fabricated through sol-gel method. The obtained photocatalysts were characterized by XRD, SEM, TEM, XPS, PL and DRS, and the influences of Cu doping on the structure and photocatalytic property were studied. The results show that when the molar ratios of Cu/Ti are 1% and 2%, Cu doping promotes anatase → rutile phase transformation. When the molar ratio of Cu/Ti is 4%, the phase transformation is inhibited. Cu element coexists in the form of Cu + and Cu 2+ , and Cu doping facilitates the separation of photogenerated electrons and holes. TEM image shows that copper oxides are dispersed on TiO 2 particles surface, which significantly reduces the optical absorption of ultraviolet region. The photocatalytic experiment results show that the photocatalytic activity of Cu–TiO 2 is lower than pure TiO 2 , and the higher doping concentration, the lower photocatalytic activity.

This review provides a detailed exploration of titanium dioxide (TiO2) photocatalysts, emphasizing structural phases, heterophase junctions, and their impact on efficiency. Key points include diverse synthesis methods, with a focus on the sol-gel route and variants like low-temperature hydrothermal synthesis (LTHT). The review delves into the influence of acid-base donors on gelation, dissects crucial drying techniques for TiO2 aerogel or xerogel catalysts, and meticulously examines mechanisms underlying photocatalytic activity. It highlights the role of physicochemical properties in charge diffusion, carrier recombination, and the impact of scavengers in photo-oxidation/reduction. Additionally, TiO2 doping techniques and heterostructures and their potential for enhancing efficiency are briefly discussed, all within the context of environmental applications.

In this paper, a comparative study on the photocatalytic degradation of the Rhodamine B (RhB) dye as a model compound using N-Fe codoped TiO 2 nanorods under UV and visible-light (λ ≥420 nm) irradiations has been performed. TiO 2 photocatalysts were fabricated as aligned nanorod arrays by liquid-phase deposition process, annealed at different temperatures from 400 to 800 °C. The effects of annealing temperature on the phase structure, crystallinity, BET surface area, and resulting photocatalytic activity of N-Fe codoped TiO 2 nanorods were also investigated. The degradation studies confirmed that the nanorods annealed at 600 °C composed of both anatase (79%) and rutile phases (21%) and offered the highest activity and stability among the series of nanorods, as it degraded 94.8% and 87.2% RhB in 120 min irradiation under UV and visible-light, respectively. Above 600 °C, the photocatalytic performance of nanorods decreased owning to a phase change, decreased surface area and bandgap, and growth of TiO 2 crystallites induced by the annealing temperature. It is hoped that this work could provide precious information on the design of ID catalyst materials with more superior photodegradation properties especially under visible-light for the further industrial applications.

This research pursued the effect of various calcination temperatures (300–1000 °C) on developing structural phases and the optical, dielectric, and photodegradation characteristics of cobalt-doped titanium dioxide nanoparticles (TiO2 NPs). The prepared NPs were characterized using X-ray diffraction (XRD), scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX), Fourier transform infrared (FTIR) spectroscopy analysis, ultraviolet–visible light (UV–VIS) spectroscopy, and photodegradation of methylene blue in the presence of visible light. XRD analysis revealed the formation of a tetragonal anatase phase for the samples calcined at 300–600 °C, while the Co-doped samples calcined at 800 °C and 1000 °C displayed a tetragonal rutile phase. The optical band gap analysis indicated that doping in the host matrix produced lower band gap energy for all the prepared samples. Dielectric measurements showed that the rutile phase heated at 800 °C had a larger dielectric constant and dielectric loss than the un-doped TiO2 and the other cobalt-doped samples. Finally, the anatase Co-doped TiO2 exhibited a maximum MB degradation of 93 % in 90 min compared to un-doped TiO2, which only degraded 14 % and rutile-TiO2 NPs (62 % degradation). The underlying mechanism responsible for the diverse photodegradation performance displayed by the anatase and rutile phases of TiO2 NPs is discussed. Overall, these results demonstrate that cobalt doping and the crystalline phase of TiO2 NPs are vital parameters involved in optimizing the photocatalytic activity of TiO2.

Among all transition metal oxides, titanium dioxide (TiO2) is one of the most intensively investigated materials due to its large range of applications, both in the amorphous and crystalline forms. We have produced amorphous TiO2 thin films by means of room temperature ion-plasma assisted e-beam deposition, and we have heat-treated the samples to study the onset of crystallization. Herein, we have detailed the earliest stage and the evolution of crystallization, as a function of both the annealing temperature, in the range 250–1000 °C, and the TiO2 thickness, varying between 5 and 200 nm. We have explored the structural and morphological properties of the as grown and heat-treated samples with Atomic Force Microscopy, Scanning Electron Microscopy, X-ray Diffractometry, and Raman spectroscopy. We have observed an increasing crystallization onset temperature as the film thickness is reduced, as well as remarkable differences in the crystallization evolution, depending on the film thickness. Moreover, we have shown a strong cross-talking among the complementary techniques used displaying that also surface imaging can provide distinctive information on material crystallization. Finally, we have also explored the phonon lifetime as a function of the TiO2 thickness and annealing temperature, both ultimately affecting the degree of crystallinity.

Background Metal oxide nanoparticles (NPs) are becoming valuable due to their novel applications. The green synthesis of TiO 2 NPs is more popular as a flexible and eco-friendly method compared to traditional chemical synthesis methods. TiO 2 NPs are the most commonly used semiconductor in dye-sensitized solar cells (DSSCs). Results The biogenic TiO 2 NPs were produced extracellularly by the marine halophilic bacterium Halomonas sp. RAM2. Response surface methodology (RSM) was used to optimize the biosynthesis process, resulting in a starting TiO 2 concentration of 0.031 M and a pH of 5 for 92 min (⁓15 nm). TiO 2 NPs were well-characterized after the calcination process at different temperatures of 500, 600, 700 and 800 °C. Anatase TiO 2 NPs (calcined at 500 °C) with a smaller surface area and a wider bandgap were nominated for use in natural dye-sensitized solar cells (NDSSCs). The natural dye used as a photosensitizer is a mixture of three carotenoids extracted from the marine bacterium Kocuria sp. RAM1. NDSSCs were evaluated under standard illumination. After optimization of the counter electrode, NDSSC Bio(10) (10 layers) demonstrated the highest photoelectric conversion efficiency (η) of 0.44%, which was almost as good as NDSSC P25 (0.55%). Conclusion The obtained results confirmed the successful green synthesis of TiO 2 NPs and suggested a novel use in combination with bacterial carotenoids in DSSC fabrication, which represents an initial step for further efficiency enhancement studies.

The present paper reports the green synthesis of TiO 2 NPs to evaluate its photocatalytic activity. In this synthesis we use Aegle marmelos leaf extract as reducing and stabilizing agent. The TiO 2 nanoparticles were characterized by using various advance analytical tools. The FTIR analysis revels the presence of different functional group present on the surface of the fabricated nanoparticles. The result of SEM analysis indicated that the prepared nanoparticles were almost spherical in nature and particles are in agglomerated state with bunch size less than 150 nm. The X-ray analysis of our synthesized nanoparticles clearly indicated that the particles are exit in anatase phase. Photocatalytic degradation studies of our nanoparticles were also evaluated against the most common nitroimidazole derivative drug ornidazole (ODZ) and the result of this study provide a good alternative path to remove the ODZ contaminants from waste water. The photocatalytic degradation of selected drug follow pseudo-first order reaction. Graphic Abstract

We examine comparatively the performance of sputtered TiO2 rutile and anatase thin films as an electron transport layer (ETL) in MAPbI3‐based perovskite solar cells. Both anatase and rutile TiO2 ETLs are deposited (on fluorine‐doped tin oxide [FTO] substrates) by magnetron sputtering in the form of nanocrystalline thin films. We systematically investigate the role of crystallographic phase composition of TiO2 ETLs on the photovoltaic performance of perovskite solar cells. The champion power conversion efficiencies (PCEs) of 18.4% and 17.7% under reverse scan mode are obtained for perovskite solar cells based on TiO2 anatase and TiO2 rutile ETL, respectively. The results show that the magnetron sputtering deposited ETLs differ from each other only in their phase composition while the overall performance of the devices is not greatly affected by the crystallographic phase of the TiO2 ETLs. Our results point to an important fact that for a proper and reliable comparison between the performance of TiO2 anatase and rutile ETLs, it is crucial to investigate films of similar morphology and structure that are synthesize under similar conditions. Anatase and rutile TiO2 that are deposited by magnetron sputtering and use as electron transport layer (ETL) in perovskite solar cell behave relatively comparable and the overall performance of the cells is not considerably affected by the crystallographic phase of TiO2 ETLs.