TiO2 Samples Research Articles

Pair distribution function analysis for oxide defect identification through feature extraction and supervised learning

Feature extraction and a neural network model are applied to predict defect types and concentrations in experimental anatase TiO2 samples. A dataset of TiO2 structures with vacancies and interstitials of oxygen and titanium is built, and the structures are relaxed using energy minimization. The features of the calculated pair distribution functions (PDFs) of these defected structures are extracted using linear methods (principal component analysis and non-negative matrix factorization) and non-linear methods (autoencoder and convolutional neural network). The extracted features are used as inputs to a neural network that maps feature weights to the concentration of each defect type. The performance of this machine learning pipeline is validated by predicting defect concentrations based on experimentally measured TiO2 PDFs and comparing the results to brute-force predictions. A physics-based initialization of the autoencoder has the highest accuracy in predicting defect concentrations. This model incorporates physical interpretability and predictability of material structures, enabling a more efficient characterization process with scattering data.

New insight into vanadium phosphorus oxides (VPO/TiO2) catalysts for NOx removal with NH3-SCR at low temperature: Relationship between non-VOx phases and SO2&H2O resistance

Enhancing SO2&H2O resistance has important environmental implications for the NH3-selective catalytic reduction (NH3-SCR) catalysts in NOx removal. Herein, vanadium phosphorus oxides (VPO) were synthesized as active phases for NH3-SCR catalysts. Non-VOx phases containing (VO)2P2O7 and δ-VOPO4 were generated by adjusting the P/V molar ratio and the atmosphere properties of the activation and calcination. The NOx conversion of the VPO-1.5/TiO2 sample did not decrease (about 90%) after 6 h exposure to 180 °C, 500 ppm SO2 and 6% H2O. The abundant acid content (especially increased content of the weak Brønsted acids) corresponding to the non-VOx phases significantly inhibited stable SO2 adsorption on the catalyst surface. In-situ DRIFTS results showed that SO2 + O2 pre-adsorption on the catalyst surface had no significant influence on the adsorbed NH3 species. Density functional theory calculation also proves that SO2 has low competitive adsorption activity with NH3 and NO in the non-VOx phases. Under more severe conditions, the non-VOx phases still minimized the influence of SO2&H2O poisoning on surface acidity by inhibiting the accumulation of ammonium bisulfate. This work proposes a mechanism for enhancing SO2&H2O resistance with non-VOx phases, which is essential for extending the application of VPO/TiO2 catalysts from alkane selective oxidation to NH3-SCR.

Synthesis and Structure of Carbon‐doped TiO2 by Carbothermal Treatment

AbstractCarbon modified titanium dioxide (TiO2) is a promising candidate for catalytic applications or fuel cells, where the modified oxide could replace currently used catalyst support materials. Carbothermally treated TiO2 was successfully prepared by annealing under acetylene/nitrogen gas flow in a rotary tube furnace. The carbon content in the TiO2 samples ranged from 5 to 14.5 wt.‐% as determined by thermogravimetric measurements. The powders showed suppression of the phase transition from anatase to rutile up to a treatment temperature of 825°C. Above 600°C rutile is the thermodynamically stable phase, therefore the suppression must be attributed to either carbon in the lattice or the reducing atmosphere in the furnace. Raman spectra revealed the characteristic G and D bands, indicating the formation of carbonaceous species in the samples. In addition, a shift of the anatase Eg(1) band was observed indicating a lattice disorder pointing toward carbon incorporation into the lattice. Diffuse reflectance spectra show sub band gap absorption together with a shift of the absorption edge. Depending on the extraction method of band gaps from spectra, the band gap values show a decrease or increase with increasing carbon content. Details of the evaluation and interpretation of the spectra are discussed.

Solvothermal Treatment of Visible‐Light‐Responsive TiO2 toward Enhanced Photocatalytic Degradation Activity of Tetracycline

AbstractPhotocatalytic degradation of organic pollutants driven by visible‐light is considered as a promising and effective water purification strategy. In this work, solvothermal treatment was carried out on visible‐light‐responsive TiO2 samples in isopropyl alcohol to improve the photocatalytic degradation performance. The effects of solvothermal treatment on the microstructure, band structure, optical properties, photoelectrochemical properties and photocatalytic activity of the obtained TiO2 samples were systematically investigated. The experimental results showed that the photocatalytic degradation performance of the treated TiO2 samples was significantly improved. The TiO2 sample treated for 24 h at 180 °C showed the optimal kinetic constant of photocatalytic degradation of tetracycline, which is 4.7 times that of pristine TiO2. This work provides some insight into the effect of solvothermal treatment on the photocatalytic properties of semiconductor photocatalysts.

A highly efficient and recyclable Pt/TiO2 thin film photocatalytic system for sustainable hydrogen production

Powder samples (P) of TiO2 and Pt/TiO2 were prepared using conventional methods. Then, thin films (TF) incorporating these powders onto SiO2 films were prepared via dip coating. The powder and thin film samples were characterized by Raman spectroscopy, FESEM, elemental mapping, ICP-OES, HRTEM, UV–vis DRS, and XPS. The samples were then tested in a water-splitting reaction to generate hydrogen, using a water/methanol mixture with a 1:1 volume ratio, and two purple lamps as the radiation sources. The results suggest that incorporating the powder photocatalyst into the thin film resulted in a significant improvement in photocatalytic performance. Furthermore, the thin film samples were more stable during three consecutive runs.

83 Development of a New Xrd Method to Evaluate Exposure to Respirable TiO2 in Workplace Air

Abstract ECHA classified TiO2 particles with an aerodynamic diameter ≤10 μm as carcinogen. Although the OELV for TiO2 is still related to inhalable particles in many jurisdictions, NIOSH recommended a REL of 2.4 mg/m3 for fine TiO2, and 0.3 mg/m3 for ultrafine TiO2. The latter implies the development of a more robust method for measuring TiO2 in workplace air. X-ray diffraction (XRD) is a powerful laboratory method for quantifying crystalline matter and is frequently used to measure respirable crystalline silica in workplaces. Rutile and anatase powders were obtained from a commercial vendor and a size fraction smaller than 10 µm was separated from these powders and used to prepare a calibration series in a calm-air dust chamber. The methodology for quantifying the rutile or anatase is performed as described in ISO 16258-1:2015 for measuring respirable crystalline silica. The limit of detection and quantification (LOD/LOQ) were for rutile 0.8/1.4 µg and anatase 0.6/1.1 µg, respectively. From these measurements, we conclude that direct on filter XRD is a powerful method for analyzing respirable TiO2 samples. Further validation of the XRD method was performed by comparing the results of 177 respirable personal samples collected on 25 mm MCE filters using Casella-HD cyclone samplers at nine TiO2 production plants with ICP-MS data gained from the same samples. Excellent correlations were obtained between the XRD and ICP-MS data for each sampling site but observed consistent site-dependent deviations explained by differences in crystallinity of the TiO2 phases and the presence of titanium-containing minerals other than rutile and anatase.

Enhanced TiO2 Photocatalytic 2 e– Oxygen Reduction Reaction via Interfacial Microenvironment Regulation and Mechanism Analysis

The photocatalytic oxygen reduction reaction (ORR) is a promising strategy that generates H2O2 with a lower energy input. Although great progress has been made in the development of photocatalysts, poor accessibility of O2 in photocatalysts interfacial microenvironment is the rate-limiting factor for the photocatalytic 2e– ORR and still little explored. Here, we design a simple method to regulate the hydrophobicity and O2 accessibility at a controllable crystal facet ratio of TiO2 photocatalyst by a facile stearic acid (SA) modification. The adsorption structure of SA bonding with TiO2 has been investigated in detail by Raman spectra, X-ray photoelectron spectroscopy, Fourier transform infrared spectra, and density functional theory calculations. It has been found that the stable ester bond is formed between SA molecules and the TiO2 surface, thus leading to the enhanced hydrophobicity with the increase of SA loading. The highest photocatalytic H2O2 production rate from 2e− ORR on SA-modified TiO2 can reach up to 3160 μM h–1 g–1, which is 1.69 times that of the corresponding pure TiO2 sample. From the results of electrochemical impedance spectroscopy and molecular dynamics simulation, the increase of the O2 concentration in the interfacial microenvironment benefiting from the SA modification is responsible for the enhancement of 2e– ORR activity rather than the increase of hydrophobicity.

Food-grade titanium dioxide translocates across the buccal mucosa in pigs and induces genotoxicity in an in vitro model of human oral epithelium

The whitening and opacifying agent titanium dioxide (TiO2) is used worldwide in various foodstuffs, toothpastes and pharmaceutical tablets. Its use as a food additive (E171 in EU) has raised concerns for human health. Although the buccal mucosa is the first area exposed, oral transmucosal passage of TiO2 particles has not been documented. Here we analyzed E171 particle translocation in vivo through the pig buccal mucosa and in vitro on human buccal TR146 cells, and the effects on proliferating and differentiated TR146 cells. In the buccal floor of pigs, isolated TiO2 particles and small aggregates were observed 30 min after sublingual deposition, and were recovered in the submandibular lymph nodes at 4 h. In TR146 cells, kinetic analyses showed high absorption capacities of TiO2 particles. The cytotoxicity, genotoxicity and oxidative stress were investigated in TR146 cells exposed to E171 in comparison with two TiO2 size standards of 115 and 21 nm in diameter. All TiO2 samples were reported cytotoxic in proliferating cells but not following differentiation. Genotoxicity and slight oxidative stress were reported for the E171 and 115 nm TiO2 particles. These data highlight the buccal mucosa as an absorption route for the systemic passage of food-grade TiO2 particles. The greater toxicity on proliferating cells suggest potential impairement of oral epithelium renewal. In conclusion, this study emphasizes that buccal exposure should be considered during toxicokinetic studies and for risk assessment of TiO2 in human when used as food additive, including in toothpastes and pharmaceutical formulations.

Effect of Temperature Sintering on Grain Growth and Optical Properties of TiO2 Nanoparticles

Titanium dioxide (TiO2) nanoparticles were prepared by the sol–gel method and the structural, morphological, and optical properties were investigated at different sintering temperatures of 500, 600, 700, 800, and 900°C. A tetragonal structure of anatase, mixed (anatase–rutile), and rutile phases are observed in the X-ray diffraction (XRD) analysis. Pure anatase phase formation occurred at 500°C, whereas anatase-to-rutile phase transformation began at 600°C, and reaching complete conversion to rutile at 800°C. The average crystallite size increased from 23 to 34 nm for anatase and 38 to 62 nm for the rutile when sintering temperature increased from 500 to 900°C. The scanning electron microscope (SEM) result presented the increase of grain size (25–100 nm) with increasing the sintering temperature. The Fourier transform infrared (FTIR) spectra demonstrated the presence of TiO2 vibrational bonds in all samples. The optical bandgaps of the sintered TiO2 nanoparticles decreased with rising sintering temperature. Photoluminescence spectra exhibited three characteristic peaks centered at 380, 450, and 550 nm. The emission intensity increased with increasing the sintering temperature. The Mie analysis was also studied to calculate scattering cross-section, forward scattering, and asymmetry for different grain sizes. The results showed that by increasing the nanoparticle diameters, the peaks of all spectra are redshifted for larger grain sizes and cross-section peaks shift to high values. In this study, the sintering temperature is observed to have a strong influence on crystalline phase transformation, microstructure, and optical properties of TiO2 nanoparticles. The TiO2 sample sintered at 900°C shows the best result to be used as luminescent material due to the low optical bandgap energy.

The sensitivity enhancement of TiO2-based VOCs sensor decorated by gold at room temperature

Detection of hazardous toxic gases for air pollution monitoring and medical diagnosis has attracted the attention of researchers in order to realize sufficiently sensitive gas sensors. In this paper, we fabricated and characterized a Titanium dioxide (TiO2)-based gas sensor enhanced using the gold nanoparticles. Thermal oxidation and sputter deposition methods were used to synthesize fabricated gas sensor. X-ray diffraction analysis was used to determine the anatase structure of TiO2 samples. It was found that the presence of gold nanoparticles on the surface of TiO2 enhances the sensitivity response of gas sensors by up to about 40%. The fabricated gas sensor showed a sensitivity of 1.1, 1.07 and 1.03 to 50 ppm of acetone, methanol and ethanol vapors at room temperature, respectively. Additionally, the gold nanoparticles reduce 50 s of response time (about 50% reduction) in the presence of 50 ppm ethanol vapor; and we demonstrated that the recovery time of the gold decorated TiO2 sensor is less than 40 s. Moreover, we explain that the improved performance depends on the adsorption-desorption mechanism, and the chemical sensitization and electronic sensitization of gold nanoparticles.

Visible light sensitive Au–TiO2 nanocomposites formed by effective attachment of Au with TiO2 nanoparticles using liquid-phase pulsed-laser ablation

Liquid-phase pulsed-laser ablation was utilized to grow visible-light-sensitive Au–TiO2 nanocomposites. We performed the nanosecond pulsed-laser ablation of a Ti target in aqueous solution of HAuCl4 of different concentrations varying from 0 mM to 0.24 mM. Structural characterization studies using transmission electron microscopy (TEM) and X ray diffraction (XRD) analyses confirmed formation of the nanoparticles of TiO2 and Au–TiO2 in respective solutions. In Au–TiO2 samples, nanocomposites formation by efficient attachment between Au and TiO2 nanoparticles was confirmed by absorption and X-ray photoelectron spectroscopy (XPS) analyses. Optical absorption analysis revealed that with the attachment of Au, there is a red shift in the onset of the absorption band of TiO2 from the ultraviolet to visible range. This red shift is found to increase from 3.5 to 2.7 eV with respect to the increase in the amount of Au present in Au–TiO2 nanocomposites. While detailed XPS analysis suggested that when the amount of Au attached with TiO2 increased, the number density of oxygen vacancy or Ti3+ states increased. Therefore the attachment of Au nanoparticles and oxygen vacancy or Ti3+ states generations in TiO2 were found to be responsible for the large red shift in the onset of the TiO2 absorption band. Consequently our study showed that single step liquid phase laser ablation method and its subsequent nonequilibrium growth conditions are useful in synthesizing Au and TiO2 nanoparticles simultaneously and also in providing efficient attachment between Au and TiO2 which is responsible for visible range sensitization of Au-TiO2 nanocomposites .

A New Combination Method of N-doped TiO2 Nanoparticles Synthesis for Heavy Metal Ions Cr(VI) Photoreduction Applications

Through a combination of biosynthetic and hydrothermal methods, N-doped TiO2 photocatalyst has been successfully synthesized using various concentrations of ammonia as a nitrogen source, namely 10% w/w (NTO10), 20% w/w (NTO20), 35% w/w (NTO35), and 50% w/w (NTO50). The synthesis of TiO2 was conducted using Aloe vera (L) Burm F. rind extract as a natural capping agent via the biosynthetic method, followed by a nitrogen doping process via the hydrothermal method. The X-ray Diffraction (XRD) analysis revealed that all phases were anatase. According to the results of the UV-Vis Diffuse Reflectance Spectroscopy (UV-Vis DRS) analysis using the Tauc-Plot method, all N-doped TiO2 samples showed a decrease in the energy gap compared to the TO sample. This indicates that the doping of TiO2 using nitrogen has been successfully doped into TiO2. The photocatalytic activity of N-doped TiO2 was evaluated for the photoreduction of the Cr(VI) model pollutant using a 24-watt LED lamp as a visible light source for 120 minutes. The results indicate that the NTO35 is the best-prepared N-doped TiO2, which showed a reduced rate for the Cr (VI) model pollutant of 50.88%, or two times greater than that of undoped TiO2.

UV Induced Photocatalytic Degradation of Caffeine Using TiO2–H-Beta Zeolite Composite

An anatase phase of the TiO2-H-beta (THB) zeolite composite photocatalyst is used for the photocatalytic degradation of caffeine, a persistent organic pollutant (POP). It is synthesized by a simple two-step sol-gel method. Phase formation, morphology, bandgap, and photocatalytic properties were analyzed using powder X-ray diffraction, scanning electron microscopy, and UV-Vis diffuse reflectance spectroscopy, respectively. The THB and the anatase TiO2 samples were then tested for the photocatalytic activity of the degradation of caffeine. Photocatalytic studies reveal that the as-prepared THB composite showed excellent activity for the degradation of 10 ppm caffeine solution. The chemical oxygen demand (COD) analysis found caffeine to have degraded with an efficiency of 96%. Scavenging experiments indicated that the hydroxide radical played an important role in the degradation of caffeine. The results highlight the role of the H-beta zeolite as an effective support to TiO2 and improved the photocatalytic activity. The study demonstrates that the THB composite could be effectively applied for the photocatalytic degradation of other POPs largely present in active pharmaceutical ingredients.

Green fabrication of titanium dioxide nanoparticles and their applications in photocatalytic dye degradation and microbial activities

The green method of metal oxide synthesis is an alternative to the more time consuming and difficult to consume traditional procedures, as the invention achieves a significant yield with minimal effort. Using this method proposed titanium dioxide (TiO2) nanoparticles (NPs) were made and used to make using different plant extracts and the characterization were analysed using X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), transmission electron microscopy (TEM), and UV−visible spectroscopy. TiO2 NPs were formed in the anatase phase, according to the XRD investigation, and the TEM confirmed their size of 15–28 nm and spherical morphology. According to scanning electron microscopic investigations, the typical particle size distribution of the individual particles was identified as being in the range of 21 nm. UV–visible spectroscopy proved the optical defects of the TiO2 NPs (2.89 eV, 2.98 eV, and 3.17 eV). FTIR was used to confirm the bio-functionality of flavonoids, M-O interactions, and surface interfaces. By using X-ray spectroscopy, it was shown that the TiO2 samples had an improved nanostructure and a 3:1 ratio of O:Ti components. In this particular study, attention was paid to both the photocatalytic and antimicrobial properties of TiO2 NPs. Producing TiO2 NPs requires efforts to reduce their toxicity in an environmentally responsible manner. When the dye methylene blue (MB), which is a significant water pollutant generated by the textile industry, was exposed to the TiO2 NPs, a high photodegradation efficiency was demonstrated, with photodegradation showing a degradation rate of 87%. According to the results, the Diameter Inhibition Zone (DIZ) possesses the highest level of inhibition against disease-causing microbes. As a consequence of these findings, an environmentally friendly and long-term viable option for water purification has been identified.

Catalytic Performance and Reaction Mechanisms of Ethyl Acetate Oxidation over the Au–Pd/TiO2 Catalysts

The development of efficient and stable catalysts is of great importance for the elimination of volatile organic pollutants (VOCs). In this work, AuPdx nanoparticles (NPs) were loaded on TiO2 through the electrostatic adsorption approach to generate the yAuPdx/TiO2 (i.e., 0.35AuPd0.46/TiO2, 0.34AuPd2.09/TiO2, and 0.37AuPd2.72/TiO2; x and y are Pd/Au molar ratio and AuPdx loading, respectively; x = 0.46–2.72; and y = 0.34–0.37 wt%) catalysts, and their catalytic activities for the oxidation of ethyl acetate were determined. The results showed that the 0.37AuPd2.72/TiO2 sample exhibited the best activity (T50% = 217 °C and T90% = 239 °C at SV = 40,000 mL/(g h), Ea = 37 kJ/mol, specific reaction rate at 220 °C = 113.8 µmol/(gPd s), and turnover frequency (TOFNoble metal) at 220 °C = 109.7 × 10−3 s−1). The high catalytic performance of the 0.37AuPd2.72/TiO2 sample was attributed to the good dispersion of AuPd2.72 NPs, the strong redox ability, the large ethyl acetate adsorption capacity, and the strong interaction between AuPdx and TiO2. Acetaldehyde, ethanol, and acetic acid are the main intermediates in the oxidation of ethyl acetate, and the loading of AuPdx NPs effectively reduces the formation of the toxic by-product acetaldehyde. The oxidation of ethyl acetate over the 0.34AuPd2.09/TiO2 sample might occur via the pathway of ethyl acetate → ethanol → acetic acid → acetate → CO2 and H2O. We believe that the obtained results may provide a useful idea for the design of bimetallic catalysts under industrial conditions and for understanding the VOCs oxidation mechanisms.

Ni enhanced reactivity of Fe/TiO2 for selective catalytic reduction of NO with CO and the mechanism investigation

The effect of surface synergetic oxygen vacancy constructed by bimetallic metal on CO selective catalytic reduction of NOx (CO-SCR) was investigated by loading Fe and Ni on TiO2. Herein, a series of NixFe1−x/TiO2 was prepared by the wet impregnation method. The microstructures, elemental states, and reactivity of the prepared samples were characterized by XRD, HRTEM, EPR, H2-TPD, CO-TPD, NO-TPD, and XPS. The results show that the synergistic effect between Ni and Fe effectively optimized the dispersion of Fe and constructed abundant Ni-O-Fe bonds. Furthermore, the excellent CO trapping capacity led to an increased number of cNi-□-Fe structures (SSOV), which effectively promotes NO activation at low temperatures. The in situ DRIFT spectra illustrated that N2O intermediate species rapidly transformed into N2-based species at 250 ℃, and the catalyst modified with Ni presented excellent NO conversion and N2 selectivity. The Ni0.2Fe0.8/TiO2 sample demonstrated almost 100% NO conversion, 93% N2 selectivity, and considerable stability with a gas hourly space velocity of 33,000 h-1 at 250 ℃. This work provides a novel way for the design and preparation of a bimetallic NO reduction catalyst to promote the further study of efficient CO-SCR catalysts.

Effect of Au nanoparticles in persistent photoconductivity and dielectric relaxations of anatase TiO2

In this research, the TiO2 samples decorated with and without Au NPs were synthesized by the simplest solvothermal method. The structural and morphological analysis of the samples were examined by XRD and TEM. Moreover, the dielectric properties highlight the frequency and temperature dependence of dielectric parameters using impedance spectroscopy. The obtained results present a critical dielectric constant of TiO2 decorated with and without Au NPs about 1800, and 3000, respectively, at room temperature. Moreover, the frequency dependent plot of modulus displays a non-Debye relaxation type. Furthermore, I–V characteristics indicate the existence of a persistent photoconductivity (PPC) at room temperature for the Au@TiO2 device. The origin of PPC is credited to the electrons trapped/de-trapped by interface states. The fabricated devices show high sensitivity to 375 nm UV illumination at 7.6 mW. These important dielectric and optoelectronics properties of the as-prepared samples make them fascinating materials for use in UV photodetector.

Voltammetric determination of arbutin using carbon paste electrode modified with low crystalline home-prepared rutile TiO2 nanoparticles

Carbon paste electrodes (CPE) were modified with commercial (Degussa P25, BDH, Merck, Hombikat) and home-prepared rutile TiO2 (HPRT) nanoparticles for the electrochemical determination of arbutin (AR) by differential pulse voltammetry technique. The optimization experiments were performed in Britton-Robinson buffer at pH 2–7 using modified CPEs. 15%-HPRT(25 °C)/CPE and 15%-HPRT(400 °C)/CPE showed the highest current values among all electrodes at optimum pH, accumulation potential, and duration time values (pH 2, 0.70V and 45 s); consequently, the electrodes were characterized by SEM-EDX, while TiO2 samples by BET and XRD techniques. Electrochemical surface areas of the electrodes were also determined. HPRT(25 °C) and HPRT(400 °C) samples have the lowest crystallinity which is the reason for their high performance. The linear working range of 15%-HPRT(25 °C)/CPE and 15%-HPRT(400 °C)/CPE electrodes was 0.5–120 μM. The detection limit for these electrodes was 32 and 40 nM, and the quantification limit was 107 and 135 nM, respectively. Interference studies, repeatability, reproducibility and the stability of the electrodes were examined, and a reaction mechanism for AR oxidation was proposed and promising results were obtained. The AR determination in a real sample, in the anti-blemish skin serum, was also performed successfully.

Bio-inspired V-TiO2 architectures with regulable surface ultrastructure for visible-light photocatalytic selective oxidation of cyclohexane

Photocatalytic selective oxidation of cyclohexane is more energy saving and sustainable when compared with traditional thermal catalysis, but highly effective visible-light photocatalyst for this reaction remains challenging. Herein, vanadium-doped TiO2 was prepared by using a solvent-thermal-assisted biotemplating method, while glycerol was used to regulate the surface ultrastructure of the catalyst. It is found that the use of the biotemplate, regulation of the surface ultrastructure of the catalyst by glycerol, as well as vanadium doping are all beneficial to improve the performance of the photocatalyst. Resultantly, the biotemplated TiO2 doped with 2 % vanadium, which has a needle-like surface ultrastructure (2 %V-CTiO2(g)) achieves the best performance for cyclohexane conversion (0.98 %), which is 7.0, 8.9 and 49 times higher than TiO2 sample without vanadium doping, surface ultrastructure adjustment and biotemplating, respectively. Characterizations and DFT calculations confirm that biotemplating and the use of glycerol endow the sample with unique morphology, oxygen vacancies and high surface area. Doping of vanadium not only changes the band structure of TiO2 but also introduces the interconversion of V4+ and V5+ into the photocatalytic process. This work offers a new approach to the green conversion of cyclohexane.

Ecotoxicological Properties of Titanium Dioxide Nanomorphologies in Daphnia magna.

In this work, the structural, vibrational, morphological, and colloidal properties of commercial 15.1 nm TiO2 nanoparticles (NPs) and nanowires (NWs, 5.6 thickness, 74.6 nm length) were studied with the purpose of determining their ecotoxicological properties. This was achieved by evaluating acute ecotoxicity experiments carried out in the environmental bioindicator Daphnia magna, where their 24-h lethal concentration (LC50) and morphological changes were evaluated using a TiO2 suspension (pH = 7) with point of zero charge at 6.5 for TiO2 NPs (hydrodynamic diameter of 130 nm) and 5.3 for TiO2 NWs (hydrodynamic diameter of 118 nm). Their LC50 values were 157 and 166 mg L-1 for TiO2 NWs and TiO2 NPs, respectively. The reproduction rate of D. magna after fifteen days of exposure to TiO2 nanomorphologies was delayed (0 pups for TiO2 NWs and 45 neonates for TiO2 NPs) in comparison with the negative control (104 pups). From the morphological experiments, we may conclude that the harmful effects of TiO2 NWs are more severe than those of 100% anatase TiO2 NPs, likely associated with brookite (36.5 wt. %) and protonic trititanate (63.5 wt. %) presented in TiO2 NWs according to Rietveld quantitative phase analysis. Specifically, significant change in the heart morphological parameter was observed. In addition, the structural and morphological properties of TiO2 nanomorphologies were investigated using X-ray diffraction and electron microscopy techniques to confirm the physicochemical properties after the ecotoxicological experiments. The results reveal that no alteration in the chemical structure, size (16.5 nm for TiO2 NPs and 6.6 thickness and 79.2 nm length for NWs), and composition occurred. Hence, both TiO2 samples can be stored and reused for future environmental purposes, e.g., water nanoremediation.