Black Hydroxylated Titanium Dioxide Prepared via Ultrasonication with Enhanced Photocatalytic Activity.
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ABSTRACT:
SUBMITTER: Fan C
PROVIDER: S-EPMC4488957 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Further applications of photocatalysis were limited by the high recombination probability of photo-induced electron-hole pairs in traditional titanium dioxide nanoparticles (TiO2 NPs). Herein, we modified them with rare earth metal via a facile sol-gel method, using tetrabutyl titanate as a precursor and terbium (III) nitrate hexahydrate as terbium (Tb) source. The resulting samples with different Tb doping amounts (from 0 to 2%) have been characterized by X-ray diffraction, UV-visible diffuse reflectance spectroscopy, X-ray photo-electron spectroscopy and a scanning electron microscope. The photocatalytic performance of Tb-doped TiO2 was evaluated by the degradation of methylene blue. The effects of Tb doping amount and initial pH value of solution were investigated in detail. The composite with Tb doping amount of 1.0 wt% showed the highest photocatalytic performance. It exhibited approximately three times enhancement in photocatalytic activity with a reaction rate constant of 0.2314 h-1 when compared with that of commercial P25 (0.0827 h-1). In addition, it presented low toxicity on zebrafishes with 96 h-LC50 of 23.2 mg l-1, and has been proved to be reusable for at least four cycles without significant loss of photocatalytic activity. A probable photocatalytic mechanism of Tb-doped TiO2 was proposed according to the active species trapping experiments. The high photocatalytic performance, excellent reusability and low toxicity of Tb-doped TiO2 indicated that it is a promising candidate material in the future treatment of dye wastewater.
| S-EPMC6837207 | biostudies-literature
Project description:We report the detailed microstructural, morphological, optical and photocatalytic studies of graphene (G) and manganese (Mn) co-doped titanium dioxide nanowires (TiO2(G-Mn) NWs) prepared through facile combined electrospinning-hydrothermal processes. The as-prepared samples were thoroughly characterized using X-ray diffraction (XRD), transmission electron microscopy, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and diffuse reflectance spectroscopy (DRS). XRD studies reveal the formation of mixed anatase-rutile phases or rutile phase depending on the dopant (Mn) precursor concentrations in the electrospinning dope and calcination temperature. The evaluation of lattice parameters revealed that the incorporation of Mn species and carbon atoms in to the lattice of anatase or rutile TiO2 could occur through substituting the sites of oxygen atoms. XPS results confirm the existence of Mn2+/Mn3+ within the TiO2 NW. Raman spectroscopy provides the evidence for structural modification because of the graphene inclusion in TiO2 NW. The optical band gap of G-Mn including TiO2 is much lower than pristine TiO2 as confirmed through UV-vis DRS. The photocatalytic activities were evaluated by nitric oxide (NOx) degradation tests under visible light irradiation. Superior catalytic activity was witnessed for rutile G-Mn-co-doped TiO2 NW over their anatase counterparts. The enhanced photocatalytic property was discussed based on the synergistic effects of doped G and Mn atoms and explained by plausible mechanisms.
| S-EPMC7153601 | biostudies-literature
Project description:Titanium oxide is widely applied as a photocatalyst. However, its low efficiency and narrow light absorption range are two main disadvantages that severely impede its practical application. In this work, black TiOx films with different chemical compositions were fabricated by tuning target voltage and controlling O2 flow during reactive DC magnetron sputtering. The optimized TiOx films with mixed phases (TiO, Ti2O3, Ti3O5, and TiO2) exhibited fantastic photothermal and photocatalytic activity by combining high light-absorptive Ti2O3 and Ti3O5 phases with the photocatalytic TiO2 phase. The sample prepared with oxygen flow at 5.6 ± 0.2 sccm and target voltage near 400 V exhibited excellent optical absorbance of 89.29% under visible light, which could improve surface temperature to 114 °C under sunlight. This film could degrade Rhodamine-B up to 74% after 150 min of UV irradiation. In a word, this work provides a guideline for fabricating black TiOx films with photothermal-assisted photocatalytic activity by reactive DC magnetron sputtering, which could avoid the usage of hydrogen and is convenient for quantity preparation.
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Project description:Visible-ultraviolet upconversion carbon quantum dots (CQDs) are synthesized with a hydrothermal method using l-glutamic acid (l-Glu) and m-phenylenediamine (MPD) and then combined with commercial nano-TiO2 to prepare CQDs/TiO2 composites. The fluorescence spectra prove that the prepared CQDs can convert approximately 600 nm visible light into 350 nm ultraviolet light. In photocatalysis experiments, CT-1, a CQDs/TiO2 composite with 1:1 molar ratio of l-Glu to TiO2, has the best degradation efficiency for methyl orange (MO). Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) experiments confirm that CT-1 is composed of quasi-spherical nano-TiO2 and CQDs with a crystal plane of graphitic carbon. CT-1 can degrade 70.56% of MO (40 ppm) within 6 h under the irradiation of a 600 nm light source, which is close to its degradation rate of 78.75% under 365 nm ultraviolet light. The apparent rate constant of CT-1 degradation equation is 12.7 times that of TiO2. Free radical scavenging experiments and electron spin resonance (ESR) tests show that the degradation ability should be attributed to the existence of h+ and •OH under visible light. Therefore, we provide a simple and low-cost solution with heavy-metal-free products to improve the photocatalytic performance of TiO2.
| S-EPMC7893638 | biostudies-literature
Project description:To alleviate the heavy burden on landfilling, construction and demolition wastes (C&DWs) are recycled and reused as aggregates in cementitious materials. However, the inherent characteristics of recycled fine aggregates (RFA), such as the high crushing index and high-water absorption, magnify the reusing difficulty. Nevertheless, attributing to the high porosity and high level of calcium hydroxides existing in the old mortar, RFA is featured with a high specific surface area and a high alkalinity. These features are useful to augment the total photo-degradation of SO2 by nano-TiO2 (NT) intermixed mortar, leading RFA to be an excellent potential carrier to load nano-TiO2 and prepare the composite photocatalyst. Hence, this study proposed to load NT onto the surface of RFAs and river sands (RSs) (the control) by the soaking method, preparing composite photocatalysts denoted as NT@RFA and NT@RS, respectively. The prepared composite photocatalysts were then utilized as sands in photocatalytic mortar to evaluate for SO2 degradation. Experiments identified a 50% higher amount of NT was loaded onto the surface of FRA relative to the control. This higher loading amount plus higher alkalinity ultimately translated into a higher photocatalytic activity. In addition, the mortar containing NT@RFA exhibited 46.3% higher physiochemical absorption and 23.9% higher photocatalytic activity than that containing NT@RS. In addition, the durability, embodied by the reuse and anti-abrasive properties, of NT@RFA exceeded that of NT@RS. The overall findings reveal that the NT@RFA not only garners beneficial effect from the high porosity but also generates positive effect from the high alkalinity. Though a number of studies deal with building materials with NT, this study is the first to load NT onto RFA and prepare composite photocatalysts which were then used as fine aggregates in building materials. Consequently, this study proves the potential high-added-value reusability of RFA in green construction materials and provides a low-cost, high-efficiency approach to degrade atmospheric SO2.
| S-EPMC6915600 | biostudies-literature
Project description:Development of conversion of biomass derivatives in combination with utilization of solar energy by photocatalysts is a promising alternative strategy for biorefineries. The photocatalytic reaction could convert glucose to a mixture of value-added chemicals under UV irradiation. Modifications of titanium dioxide (TiO2) nanoparticles by metal or metalloid (i.e., B and Ag) and nonmetal (i.e., N) dopants were carried out. The effects of co-doping (i.e., B/N and Ag/N) on physicochemical characteristics of the modified photocatalysts, photocatalytic glucose conversion, and the yields of the target chemical products (i.e., gluconic acid, xylitol, arabinose, and formic acid) were studied. The doping of the photocatalysts by different single dopants could improve the performance in terms of productivity and was further enhanced by the synergism from co-doping. The improvement in catalytic performances of the photocatalysts corresponded with the alterations in physicochemical characteristics of the catalysts resulting from the dopants.
| S-EPMC7439370 | biostudies-literature
Project description:Rationale: Maternal immune responses can promote allergy development in offspring. Pilot data show that neonates of mother mice exposed during pregnancy to air pollution particles have increased allergic susceptibility. Objective: We investigated whether inflammatory response to titanium dioxide (TiO2) particles earlier considered immunologically ‘inert’ is enhanced during pregnancy. Methods: Pregnant BALB/c mice (or non-pregnant controls) received particle suspensions intranasally at day 14 of pregnancy. Lung inflammatory responses were evaluated 19 and 48 h after exposure. Results: Pregnant mice showed robust and persistent acute inflammatory responses after exposure to TiO2, while non-pregnant females had the expected minimal responses. Genomic profiling identified genes differentially expressed in pregnant lungs exposed to TiO2. Neonates of mothers exposed to TiO2 (but not PBS) developed increased susceptibility to allergens. Conclusion: Pregnancy enhances lung inflammatory responses to otherwise relatively innocuous inert particles. Keywords: Particles exposure, pregnancy vs normal
2007-06-30 | GSE7475 | GEO
Project description:Nitrate is often removed from groundwater by ion exchange (IX) before its use as drinking water. Accumulation of nitrate in IX brine reduces the efficiency of IX regeneration and the useful life of the regeneration brine. For the first time, we present a strategy to photocatalytically reduce nitrate in IX brine, thereby extending the use of the brine. Titanium dioxide (Evonik P90), acting as photocatalyst, reduced nitrate effectively in both synthetic brines and sulfate-removed IX brine when formic acid (FA) was used as the hole scavenger (i.e., electron donor) and the initial FA to nitrate molar ratio (IFNR) was 5.6. Increasing the NaCl level in the synthetic brine slowed the nitrate reduction rate without affecting by-product selectivity of ammonium and gaseous N species (e.g., N(2), N(2)O). In a non-modified IX brine, nitrate removal was greatly inhibited owing to the presence of sulfate, which competed with nitrate for active surface sites on P90 and induced aggregation of P90 nanoparticles. After removing sulfate through barium sulfate precipitation, nitrate was effectively reduced; approximately 3.6 × 10(24) photons were required to reduce each mole of nitrate to 83% N Gases and 17% NH(4)(+). To make optimum use of FA and control the residual FA level in treated brine, the IFNR was varied. High IFNRs (e.g., 4, 5.6) were found to be more efficient for nitrate reduction but left higher residual FA in brine. IX column tests were performed to investigate the impact of residual FA for brine reuse. The residual FA in the brine did not significantly affect the nitrate removal capacity of IX resins, and formate contamination of treated water could be eliminated by rinsing with one bed volume of fresh brine.
| S-EPMC4741382 | biostudies-literature
Project description:The recent discovery of "black" TiO2 nanoparticles with visible and infrared absorption has triggered an explosion of interest in the application of TiO2 in a diverse set of solar energy systems; however, what a black TiO2 nanoparticle really is remains a mystery. Here we elucidate more properties and try to understand the inner workings of black TiO2 nanoparticles with hydrogenated disorders in a surface layer surrounding a crystalline core. Contrary to traditional findings, Ti(3+) here is not responsible for the visible and infrared absorption of black TiO2, while there is evidence of mid-gap states above the valence band maximum due to the hydrogenated, engineered disorders. The hydrogen atoms, on the other hand, can undergo fast diffusion and exchange. The enhanced hydrogen mobility may be explained by the presence of the hydrogenated, disordered surface layer. This unique structure thus may give TiO2, one of the most-studied oxide materials, a renewed potential.
| S-EPMC3607837 | biostudies-other
Project description:Over the past few decades, two-dimensional (2D) and layered materials have emerged as new fields. Due to the zero-band-gap nature of graphene and the low photocatalytic performance of MoS2, more advanced semiconducting 2D materials have been prompted. As a result, semiconductor black phosphorus (BP) is a derived cutting-edge post-graphene contender for nanoelectrical application, because of its direct-band-gap nature. For the first time, we report on robust BP@TiO2 hybrid photocatalysts offering enhanced photocatalytic performance under light irradiation in environmental and biomedical fields, with negligible affected on temperature and pH conditions, as compared with MoS2@TiO2 prepared by the identical synthesis method. Remarkably, in contrast to pure few layered BP, which, due to its intrinsic sensitivity to oxygen and humidity was readily dissolved after just several uses, the BP@TiO2 hybrid photocatalysts showed a ~92% photocatalytic activity after 15 runs. Thus, metal-oxide-stabilized BP photocatalysts can be practically applied as a promising alternative to graphene and MoS2.
| S-EPMC4346807 | biostudies-other