Anatase Phase Research Articles

Polymorphs of Titanium Dioxide: An Assessment of the Variants of Projector Augmented Wave Potential of Titanium on Their Geometric and Dielectric Properties.

Titanium dioxide (TiO2) is one of the important functional materials owing to its diverse applications in many fields of chemistry, physics, nanoscience, and technology. Hundreds of studies on its physicochemical properties, including its various phases, have been reported experimentally and theoretically, but the controversial nature of relative dielectric permittivity of TiO2 is yet to be understood. Toward this end, this study was undertaken to rationalize the effects of three commonly used projector augmented wave (PAW) potentials on the lattice geometries, phonon vibrations, and dielectric constants of rutile (R-)TiO2 and four of its other phases (anatase, brookite, pyrite, and fluorite). Density functional theory calculations within the PBE and PBEsol levels, as well as their reinforced versions PBE+U and PBEsol+U (U = 3.0 eV), were performed. It was found that PBEsol in combination with the standard PAW potential centered on Ti is adequate to reproduce the experimental lattice parameters, optical phonon modes, and the ionic and electronic contributions of the relative dielectric permittivity of R-TiO2 and four other phases. The origin of failure of the two soft potentials, namely, Ti_pv and Ti_sv, in predicting the correct nature of low-frequency optical phonon modes and ion-clamped dielectric constant of R-TiO2 is discussed. It is shown that the hybrid functionals (HSEsol and HSE06) slightly improve the accuracy of the above characteristics at the cost of a significant increase in computation time. Finally, we have highlighted the influence of external hydrostatic pressure on the R-TiO2 lattice, leading to the manifestation of ferroelectric modes that play a role in the determination of large and strongly pressure-dependent dielectric constant.

Pb(II) Uptake from Polluted Irrigation Water Using Anatase TiO2 Nanoadsorbent.

The adsorption characteristics of titanium dioxide nanoparticles (nano-TiO2) for the removal of Pb(II) from irrigation water were investigated in this work. To accomplish this, several adsorption factors, such as contact time and pH, were tested to assess adsorption efficiencies and mechanisms. Before and after the adsorption experiments, commercial nano-TiO2 was studied using X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM), energy dispersive spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). The outcomes showed that anatase nano-TiO2 was remarkably efficient in cleaning Pb(II) from water, with a removal efficiency of more than 99% after only one hour of contact time at a pH of 6.5. Adsorption isotherms and kinetic adsorption data matched the Langmuir and Sips models quite well, showing that the adsorption process occurred at homogenous sites on the surface of nano-TiO2 by forming a Pb(II) adsorbate monolayer. The XRD and TEM analysis of nano-TiO2 following the adsorption procedure revealed a non-affected single phase (anatase) with crystallite sizes of 9.9 nm and particle sizes of 22.46 nm, respectively. According to the XPS data and analyzed adsorption data, Pb ions accumulated on the surface of nano-TiO2 through a three-step mechanism involving ion exchange and hydrogen bonding mechanisms. Overall, the findings indicate that nano-TiO2 has the potential to be used as an effective and long-lasting mesoporous adsorbent in the treatment and cleaning of Pb(II) from water bodies.

Enhanced shelf-life of peach fruit in alginate based edible coating loaded with TiO2 nanoparticles

This study was conducted to determine the effects of nanoparticle based edible coatings on post-harvest quality of peach fruits during 7 days storage at ambient temperature. The edible coatings consisted of sodium alginate (SA) supplemented with green synthesized titanium dioxide (TiO2) nanoparticles and mousami peel extract (MPE). TiO2 nanoparticles with diameters ranging from 5 nm to 20 nm were synthesized with Citrus limetta (mousami) peel extract. The structural analysis of TiO2 nanoparticles were studied by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Transmission electron microscopy (TEM). The optical properties were studied by UV-VIS spectroscopy which confirmed the anatase phase of TiO2 nanoparticles. Different nanoemulsion coatings of SA, SA-TiO2 nanoparticles (SA-NT) and SA-NT-MPE were developed to study various post-harvest quality attributes of peaches. Coating treatment significantly reduced percent weight loss, retained antioxidant activity and ascorbic acid content than control samples. The coating had a significant (p<0.05) impact on polyphenol oxidase activity, titratable acidity and firmness of peach samples during storage. Similarly, coated peach samples retained color index and slowed down the yeast and mold count during the storage period. At the end of the storage period, coated samples with coating solutions containing TiO2 nanoparticles and MPE exhibited the lowest yeast and mold counts (4.17 ± 0.12 log10 cfu g−1) whereas uncoated peach samples showed the highest yeast and mold counts (7.15 ± 0.09 log10 cfu g−1). Therefore, this study demonstrated the ability of nanoemulsion as coating agent in maintaining the quality and extending the self-life of peach fruit for up to 7 days at ambient temperature.

Nb/TiO2 oxides: A study of synthesis and electron transport mechanism as an ETL in a solar device

Efficient solar devices to energy conversion are the key to a sustainable future. TiO2 dye solar cells are systems that present limited energy conversion efficiency due to recombination reactions. An alternative to reduce the back-electron recombination is the insertion of new oxides in electron transport material, such as Nb. However, what are the changes in electron lifetime and collection time caused by Nb insertion in TiO2 photoanodes? This work aims to analyze TiO2 dye solar devices with different Nb proportions synthesized by an easy and low-cost particle preparation methodology, Pechini. The techniques performed were X-ray Diffraction (XRD), Scanning Electronic Microscopy (SEM), and X-ray fluorescence to particle characterization. To the electrochemical analysis of the cells, j-V curves, Electrochemical Impedance Spectroscopy (EIS), charge extraction, Intensity Modulated Photovoltage Spectroscopy (IMVS), and Intensity-Modulated Photocurrent Spectroscopy (IMPS) were performed. The results showed a mix of anatase and rutile phase to TiO2 with Nb insertion and at the 5% of Nb proportion has been able to generate a cell with better electrochemical parameters (PCE = 5.43 %; j = 6.34 mA cm−2). The creation of energy substates below the conduction band has been able to increase the collection time (0.1748 s) and electron lifetime (0.15514 s) when compared to the cell with bare TiO2, suppressing the back-electron recombination but also difficulting the collection reaction.

The enhancement of TiO2 nanotubes performance towards methanol oxidation after surface functionalization with exfoliated graphene and nickel oxide

Platinum-free electrocatalysts for methanol oxidation are developed. The catalysts are composed of highly ordered porous titanium dioxide nanotubes (TNTs) decorated with sole NiO (TNi) or functionalized with NiO/graphene (TNiG). XRD proves the formation of the anatase phase in a composite with NiO and graphene. Raman spectra reveal the anatase peaks besides the D and G bands of graphene. SEM images show an ultrafine structure of TNTs with an average diameter of 50 nm and tube lengths lie in the range of 580 - 640 nm with a wall thickness of 6 nm covered with a uniformly dispersed spherical Ni species. The XPS spectra verify the existence of Ni (OH)2 and NiOOH alongside metallic Ni on the TNT surface. The methanol oxidation test demonstrates a high current density for TNiG that is 73.6 mA/cm2 compared to 36.7 mA/cm2 for TNi at a scan rate of 5 mV/s attaining comparable values to noble metal/TNT composites. The high performance is attributed to the high surface coverage of the TNiG catalyst which is one order of magnitude higher than the TNi catalyst. Surface modification of TNT with Ni and G is found to facilitate the adsorption of methanol and alters the electronic properties, thereby promoting the methanol electro-oxidation activity.

Photocatalytic performance of Nd–TiO2 coatings: effect of voltage and frequency

Neodymium (Nd)–titanium dioxide (TiO2) micro-arc oxidation (MAO) coatings were formed in a phosphate-based electrolyte with the addition of neodymium (III) oxide (Nd2O3) using suitable voltages and frequencies. Scanning electron microscopy results revealed that the coatings varied with different voltages and frequencies. Furthermore, composition analysis showed the neodymium–titanium dioxide coatings were mainly composed of anatase and rutile phases. Meanwhile, the anatase content increased and then decreased. In addition, X-ray photoelectron spectroscopy results indicated that the titanium (Ti) 2p spin–orbit components of the neodymium–titanium dioxide coatings shifted toward a higher binding energy, suggesting that some of the neodymium (Nd3+) ions combined with the titanium dioxide lattice, leading to dislocation. Furthermore, photocatalytic experiment results showed that the photocatalytic activity of neodymium–titanium dioxide coatings can be greatly enhanced with a moderate amount of neodymium ions. However, an excessive amount of neodymium ions does not improve the photocatalytic activity further.

Kinetic and Adsorption Mechanism of Methylene Blue by Nanocomposite TiO2/Diatomite and Its Components

Studies on the kinetics of adsorption of methylene blue dye (MB) from an aqueous solution on a DDT photocatalyst (nanoscale titanium dioxide in the anatase phase deposited on diatomite) and its components – diatomite D and anatase TiO2 are presented. The effect of the initial concentration and pH of the MB solution on the adsorption process rate is investigated. The kinetic adsorption data were processed using two simplified kinetic models – of the pseudo-first and pseudo-second order. A model of the kinetics of intraparticle diffusion was used to study the adsorption mechanism. It was found that the kinetics of adsorption of methylene blue on the surface of D, TiO2 and DDT is best described by a pseudo-second order model. It is shown that the adsorption of methylene blue on D and DDT is a multi-stage process with adsorption on the outer surface and inside the particles, and th

Optical, and electrical conductivity properties of ZnO and TiO2 nanoparticles scattered in PEO-PVA for electrical devices

Polyvinyl alcohol (PVA)/Polyethylene oxide (PEO) has been blended and doped with zinc oxide and titanium oxide nanoparticles. Different concentration of the prepared ZnO and TiO2 NPs make a change in PVA/PEO- ZnO/TiO2 NPs nanocomposites films improve the characterization of PVA/PEO. XRD scans show two broad peaks at about 18.8° and 21.95° for PVA/PEO blend. XRD scans show of PVA/PEO- ZnO/TiO2 NPs nanocomposites films obtain the hexagonal structure of ZnO and the anatase phase of TiO2 NPs. The addition of dopants in the PVA/PEO blend results in a reduce in degree of crystallinity compared to the pure blend. This is evident from the decrease in the crystallinity index (Xc value) from 37.25 to 22.31. This reduction in crystallinity can have implications for the material's opticla, thermal, and electrical properties, and should be considered when evaluating its suitability for specific applications. FT-IR results show changes in intensity of bands that could be assigned to the strong interaction between PVA/PEO and ZnO/TiO2 nanoparticles. The Egopt values reduced by raising laser ablation time due to unstructured defects that enhanced the density of localized states in the band gap, dropping from 4.72 eV to 3.0 eV for direct transitions and from 3.05 eV to 2.35 eV for indirect transitions. It undergoes complete decomposition at a higher temperature, resulting in a mass percentage of 45 ± 0.3 wt%. In comparison, the pure polymer blend sample has a lower mass percentage of 33 ± 0.03 wt% during the same temperature range. The fabricated system of PVA/PEO- ZnO/TiO2 NPs nanocomposites films showing improved in AC conductivity and dielectric characteristics and could be suggested in electrical applications.

Inexpensive hydrophobic and infrared reflective coatings on the cotton and silk fabrics using sol-gel dip coating technique

Several important practical applications, such as covid-19 front line worker garments and on-demand military apparel, require anti-water (hydrophobic) absorption and highly luminous clothing. Industrial and rapid production of these fabrics is highly expensive and under extensive research. In this work, we report an economical titania based superhydrophobic cotton and silk fabrics by wet chemical sol–gel dip coating technique. The structural characteristics of the textiles were studied using XRD, which revealed an anatase phase of titania. Wetting study on titania coated cotton and silk materials demonstrated contact angles of 146O and 136O, respectively. Additionally, in the ultraviolet and infrared wavelengths, diffused reflectance spectroscopy supported 84% and 92% reflectivity, respectively. As a result, the coated fabric proved to be an outstanding hydrophobic and reflective material that may be recommended for numerous maintenance-free apparel applications.

One Step Synthesis of TiO2-Activated Carbon Composite Using Hydrothermal Method with Mass Variation of Activated Carbon

One effort to increase the photocatalytic activity of TiO2 is to immobilize it on the surface of the sorbent material. This study aims to produce TiO2-Activated Carbon (TiO2-AC) composites which have higher photocatalytic activity than TiO2, using a simple method. The synthesis of TiO2-AC composites was carried out using the hydrothermal method. The synthesis process was initiated by mixing TTIP, ethanol, H2O, and activated carbon with various masses (5 g, 10 g, 15 g, and 20 g). The mixture was then put into a hydrothermal autoclave and heated at 180°C for 12 hours. The material is then washed until the pH is neutral, and then dried. The TiO2-AC composite powder was then calcined at 500°C for 3 hours. Based on the photocatalytic test of the TiO2-AC composite on the degradation of methylene blue compounds, it was shown that composite with a mass variation of 10 g activated carbon (TiO2-AC/10) had the highest photocatalytic activity. FTIR characterization of the sample TiO2-AC/10 showed a shift in the peak wave number of the hydroxyl and carbon groups. Meanwhile, the results of morphological analysis using SEM showed that TiO2 particles had adhered to the AC surface, which was also confirmed by EDX data in the presence of Ti and O elements in the synthesized material. The results of the crystallinity analysis showed that the 100% synthesized TiO2 was the anatase phase with a crystalline size of 1.80−14.14 nm. This study open up opportunities for the development of TiO2-based composite materials for large-scale environmental remediation applications.

Photocatalytic Glycerol Conversion and Rhodamine B Degradation: Influence of TiO2 Properties by Transformation of Anatase and Rutile Phases

Photocatalytic Glycerol Conversion and Rhodamine B Degradation: Influence of TiO2 Properties by Transformation of Anatase and Rutile Phases

Corrosion behavior of self-organized TiO2 nanotubular arrays grown on Ti6Al4V for biomedical applications

The electrochemical interactions between a biomaterial and a human fluid are important to understand when developing surfaces on titanium biomedical composites to improve bone regeneration, healing times, and longevity. Electrochemical corrosion is a major problem in implant-tissue interaction in that environment. The purpose of this research is to use different electrochemical methods such as open circuit potential (OCP), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) to examine the effect of self-organized TiO2 nanotubular surfaces on the corrosion resistance of Ti6Al4V surface. The electrochemical behavior of polished Ti6Al4V (control), and anodized samples at a constant voltage of 30V and various time-periods of anodization, such as 3hr, 4hr, and 5hrs respectively is the main focus of our study. All the anodized samples were annealed at 500 °C for 3hr with preheating rate of 5 °C per minute. The resistance of the nanotubular structure is improved after annealing because the anatase phase is stabilised, and the fluoride ions are removed. The electrochemical behavior of the nanotubular surfaces were investigated by using the simulated body fluid (SBF, 7.4 pH) solution. Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), X-ray Diffraction (XRD), Atomic Force Microscopy (AFM), and a Drop Shape Analyzer were all used to investigate the nanotubular morphology, chemical compositions, and structure. According to the findings, the anodic oxidation process results in a nanotubular structure that improves the surface area and influences the surface's chemical composition. Surfaces with self-organized TiO2 nanotubular structures had greater corrosion resistance than polished Ti6Al4V because the passive film had a larger surface area and a more dispersed amorphous crystal structure. Finally, the physical condition of the post-electrochemical treated sample was evaluated by the SEM images and compositional analysis by the EDS and XRD. The PDP curves showed the corrosion rate of the samples polished Ti6Al4V, TiO2 30V 3hr, TiO2 30V 4hr, and TiO2 30V 5hrs are 0.39, 0.35, 0.09, and 0.24 mm per year respectively. Similarly, the efficiencies of the anodized samples TiO2 30V 3hr, 4hr, and 5hrs are 9.96, 76.44, and 38.30% respectively. When comparing all of the anodized samples, the overall corrosion resistance is improved by 2 times.

TiO2–SiO2–Ag electrospun fibers for oxytetracycline detection by SERS

The presence of antibiotic residues such as oxytetracycline (OTC) in wastewater effluents has generated the need to monitor trace concentrations due to the development of bacterial resistance. Surface Enhanced Raman Spectroscopy (SERS) is a promising technique in detection and identification a low concentrations (ng/L) with no sample preparation. A fibrillar support Titania-Silica doped with silver particles was developed in the SERS technique focused on the detection of OTC. The ceramic fibers TiO2SiO2 obtained presented phases of Rutile, Anatase and Amorphous Silica with diameters of 335 ± 76 nm. The fibers were doped with Ag by electrodeposition, showed Ag nanoparticles with sizes from 30 nm to the formation of dendritic structures with sizes greater than 1 μm, depending on the time and voltage applied during synthesis. The support doped with Ag for 30 s at 19 V presented the highest amplification factor (AF) in SERS of 44 for the band at 1278 cm−1.

Facile synthesis of thermally stable anatase titania with a high-surface area and tailored pore sizes

Both affordability and stability are important for commercial-scale production and industrial applications of TiO2. In addition, the ability to tailor nanostructure and physicochemical properties can provide advantages for future applications. Herein a facile sol‒gel process was investigated by using titanyl sulfate as an inexpensive feedstock reacting with water in the media of acetic acid and isopropanol. An anatase phase was readily produced at 65 °C, followed by drying at 80 °C. The anatase was stable up to 800 °C due to the residual sulfate and nitrogen, where sulfate and ammonium slowly decomposed when heating beyond 400 °C. The monolithic TiO2 xerogels were composed of agglomerated TiO2 spherical particles with diameters of ca. 50 or 100 nm. The TiO2 spherical particles were built by anatase crystallites with a diameter of ca. 5 nm. As a result, the TiO2 exhibited both bimodal mesopores and macropores: Large mesopores (10‒30 nm) were present due to the void spaces between the TiO2 spherical particles, while the smaller mesopores (ca. 3 nm) were due to the void spaces between the anatase crystallites within each TiO2 particle. There were also larger macropores (a few micrometers), which were caused by gas bubbles generated during the sol‒gel reactions. From a mass transfer viewpoint, these large pores within TiO2 xerogels could have advantages in their potential applications for catalysis and/or filtration processes.Graphical A thermal stable anatase TiO2 with large mesopores synthesized via sol‒gel reactions from TiOSO4.

Chitosan nanoparticles loaded with mesosulfuron methyl and mesosulfuron methyl + florasulam + MCPA isooctyl to manage weeds of wheat (Triticum aestivum L.)

Abstract Nanoherbicides are articulated by empowering the potential of nanotechnology for the efficacious delivery of chemical or biological herbicides with the aid of nanomaterial‐based herbicide combinations. Therefore, the goal of this work was to investigate the chitosan nanoparticles loaded with mesosulfuron methyl and mesosulfuron methyl + florasulam + (2-methyl-4-chlorophenoxyacetic acid) MCPA isooctyl herbicides as a possible environmentally benign substitute to manage weeds in wheat. Due to intriguing characteristics including biocompatibility, low allergenicity, biodegradability, and nontoxicity, chitosan biopolymers as sustainable chitin derivatives have received intense scrutiny in the biomedical business. The manufactured nanoparticles were characterized by using ultraviolet absorbance, scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). The average particle size as revealed by SEM was 40–70 nm in a cluster form with the porous structure. The maximum absorption peaks of both nanoparticles of mesosulfuron methyl and mesosulfuron methyl + florasulam + MCPA isooctyl were 330 and 360 nm. The FT-IR analysis showed an intensive peak at 2θ value of 30.55° for mesosulfuron methyl and 32.79° for mesosulfuron methyl + florasula + MCPA isooctyl, which correspond to the 78 and 198 planes of the anatase phase, respectively. The nanoparticles were sprayed at the third to fourth leaf stages of the targeted weeds. Seven different doses were applied. A total of 100% mortality and visual injury were caused by the chitosan-based nanoparticles of both herbicides at the recommended dose of standard herbicide. The 5-fold lower dose showed the minimum chlorophyll content (5.75%), plant height (2.35 cm), fresh biomass (1.08 g), and dry biomass (0.33 g) of a weed mixture. For the same traits, the herbicide nanoparticles at 10-fold lower dose of commercial herbicides exhibited a similar effect as the recommended dose. Nanoherbicides could recuperate the conventional herbicide effectiveness by enhancing the stability and reducing the toxicity.

Titania nanoparticles for photocatalytic degradation of ethanol under simulated solar light.

TiO2 nanoparticles were synthesized by laser pyrolysis from TiCl4 vapor in air in the presence of ethylene as sensitizer at different working pressures (250-850 mbar) with and without further calcination at 450 °C. The obtained powders were analyzed by energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, X-ray diffractometry, and transmission electron microscopy. Also, specific surface area and photoluminescence with optical absorbance were evaluated. By varying the synthesis parameters (especially the working pressure), different TiO2 nanopowders were obtained, whose photodegradation properties were tested compared to a commercial Degussa P25 sample. Two series of samples were obtained. Series "a" includes thermally treated TiO2 nanoparticles (to remove impurities) that have different proportions of the anatase phase (41.12-90.74%) mixed with rutile and small crystallite sizes of 11-22 nm. Series "b" series represents nanoparticles with high purity, which did not require thermal treatment after synthesis (ca. 1 atom % of impurities). These nanoparticles show an increased anatase phase content (77.33-87.42%) and crystallite sizes of 23-45 nm. The TEM images showed that in both series small crystallites form spheroidal nanoparticles with dimensions of 40-80 nm, whose number increases with increasing the working pressure. The photocatalytic properties have been investigated regarding the photodegradation of ethanol vapors in Ar with 0.3% O2 using P25 powder as reference under simulated solar light. During the irradiation H2 gas production has been detected for the samples from series "b", whereas the CO2 evolution was observed for all samples from series "a".

Photocatalytic and photovoltaic applications of green synthesized titanium oxide (TiO2) nanoparticles by Calotropis gigantea extract

Titanium di oxide (TiO2) nanoparticles were prepared by green synthesis method using leaves, seeds, and flower solvent extract of Calotropis gigantean medicinal plant. The X-ray diffraction (XRD) analysis of the prepared TiO2 nanoparticles shows tetragonal structure of anatase phase TiO2. The quantum confinement of the TiO2 particles by the inclusion of active biomolecules was confirmed by optical studies. The polycrystalline nature of the prepared nanoparticles was confirmed by XRD and SAED analysis. The particle size reduction and increase of band gap energy are noted with Calotropis gigantean leaf assisted TiO2, while it increases with flower and seed assisted TiO2. The prepared nanoparticles exhibit the size dependent photocatalytic activity and solar cell fabrication. Calotropis gigantean leaf assisted TiO2 NPs had the highest photocatalytic activity, completely degrading methylene blue in 60 min with an 96 % of degradation, due to a low recombination rate of photo-generated electrons and holes. The prepared Calotropis gigantean plant assisted TiO2 nanoparticles boosted the concentration of OH• and O2• radicals in the solution, which is beneficial for enhancing the photodegradation rate of organic compounds. Plant derivative based TiO2 nanoparticles are the best candidates due to simplicity and cost-effectiveness leading to economical and operational advantages in the large-scale synthesis of nanoparticles.

Preparation of TiO2/activated carbon nanomaterials with enhanced photocatalytic activity in paracetamol degradation

Despite the advances in the photocatalytic degradation method to treat wastewater, obtaining efficient, stable, and cost-effective materials for this application is still challenging. The present study employed a simple and effective sol-gel method to prepare a photocatalyst consisting of titanium dioxide (TiO2) and activated carbon (AC). Four types of catalysts were obtained with different proportions of TiO2:AC, which were named TiO2/AC-05, TiO2/AC-10, TiO2/AC-30, and TiO2/AC-70. The surface area and the pore volume of TiO2 were significantly increased after incorporating AC, from 5% to 70%. X-ray diffraction and Raman spectroscopy showed that TiO2 is present in the anatase phase, with a particle size distribution centered at 11 nm, obtained by transmission electron microscopy (TEM). Moreover, TEM and X-ray photoelectron spectroscopy (XPS) analysis confirmed the interaction of both materials, resulting in a TiO2/AC nanocomposite combination. All four combination types were evaluated as the photocatalyst for Paracetamol degradation to investigate which material has the best photocatalytic performance. TiO2/AC-30 showed the highest efficient activity and achieved about 95% of the Paracetamol photodegradation. Therefore, the TiO2/AC-30 nanocomposite can be reused because it showed activity after five cycles of Paracetamol photodegradation. This study indicates that TiO2/AC-30 can be a good candidate for water purification containing emergent contaminants.

Facile tailoring of photoluminescence properties of surface-modified TiO2 nanocrystals

Surface modification of metal oxide nanomaterials is one of the promising techniques for tailoring its optoelectronic properties. In this paper, a novel method has been reported for controlling the optical band gap, generation of trapping states and inhibiting the charge carrier’s recombination rate in TiO2 nanocrystals (NCs). It has been achieved through the surface modification of TiO2 NCs using organic ligands such as formamide (FA) and polyethylene glycol (PEG). Investigations reveal that the luminescence properties have also been tuned exhibiting efficient visible light-harvesting photocatalytic activity. All these have been attributed to the interaction between ligands (PEG) and TiO2 forming deep electronic states associated to C-C and C-O bonds which facilitate blue and green wavelength emissions. On the other hand, FA plays an important role as capping ligand and nitriding agent generating shallow and deep trapping states endowed with visible emission at higher wavelength. Furthermore, nitrogen doped functionalized TiO2 NCs (N-TiO2) using urea are prepared solvothermally at temperature as low as 150 °C and pressure higher than 1 atm. Under that conditions, well defined N-TiO2 anatase phase NCs show a band gap of 2.3 eV and exhibit slow electron hole recombination which have been discussed with an emphasis in view of surface modification.

Variation in Metal-Support Interaction with TiO2 Loading and Synthesis Conditions for Pt-Ti/SBA-15 Active Catalysts in Methane Combustion.

The control of catalytic performance using synthesis conditions is one of the main goals of catalytic research. Two series of Pt-Ti/SBA-15 catalysts with different TiO2 percentages (n = 1, 5, 10, 30 wt.%) were obtained from tetrabutylorthotitanate (TBOT) and peroxotitanate (PT), as titania precursors and Pt impregnation. The obtained catalysts were characterized using X-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy (TEM), N2 sorption, Raman, X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), hydrogen temperature-programmed reduction (H2-TPR) and H2-chemisorption measurements. Raman spectroscopy showed framework titanium species in low TiO2 loading samples. The anatase phase was evidenced for samples with higher titania loading, obtained from TBOT, and a mixture of rutile and anatase for those synthesized by PT. The rutile phase prevails in rich TiO2 catalysts obtained from PT. Variable concentrations of Pt0 as a result of the stronger interaction of PtO with anatase and the weaker interaction with rutile were depicted using XPS. TiO2 loading and precursors influenced the concentration of Pt species, while the effect on Pt nanoparticles' size and uniform distribution on support was insignificant. The Pt/PtO ratio and their concentration on the surface were the result of strong metal-support interaction, and this influenced catalytic performance in the complete oxidation of methane at a low temperature. The highest conversion was obtained for sample prepared from PT with 30% TiO2.