Search

Photocatalytic hydrogen production is of great significance for the transformation of energy system. To improve the hydrogen production performance, nano-photocatalysts including pure TiO 2 and NiO-TiO 2 were prepared by sol-gel method in this paper. To unravel reaction intermediates and pathways, the adsorption experiments and photocatalytic reaction of ethanol over the photocatalysts were carried out in combination with in situ DRIFTS technique, and the main products in the photocatalytic process were detected through gas chromatography. The results showed that 2NiO-TiO 2 as the optimum photocatalyst can yield the maximum H 2 rate at 20.10 mmol g−1 h−1. For the adsorption of ethanol on TiO 2 and 2NiO-TiO 2 , the molecular form of ethanol is more dominant than the dissociated form, and CH 3 CH 2 OTi is more easily generated on 2NiO-TiO 2 than pure TiO 2. The hydrogen production pathway changes by doping with NiO, reducing the production of acetic acid and aldehydes and producing the important intermediate CH 2 CHOTi. [Display omitted] • The H 2 production using anatase doping different amount of NiO was compared. • 2 % NiO-TiO 2 exhibited the optimum activity of hydrogen production and stability. • The selectivity (organic products) of ethanol photocatalysis was investigated. • The mode of adsorption and surface species was ensured by in situ DRIFTS. [ABSTRACT FROM AUTHOR]

The inclusion of particles in a polymeric substrate to achieve certain properties is a well-known practice. In the case of textile substrates, this practice may deeply affect the structure of the produced yarns, as even a filament with no textile applications can be obtained. In this manuscript, titanium dioxide (TiO2) particles were incorporated into polyester (PET) chips and the influence of these fillers on the properties of yarn and fabric, and the ultraviolet protection factor (UPF) was assessed. For this purpose, rutile and anatase crystalline forms of TiO2, as well as the size of the particles, were evaluated. Moreover, parameters such as mechanical properties, orientation of the macromolecules and thermal behavior were analyzed to ensure that the textile grade is maintained throughout the production process. The results showed that the inclusion of micro- and nanoparticles of TiO2 decreases the molecular weight and tenacity of PET. Also, although orientation and crystallinity varied during the textile process, the resulting heatset fabrics did not present important differences in those parameters. Finally, the attainment of textile-grade PET-TiO2 fabrics with UPF indexes of 50+ with both rutile and anatase and micro- and nano-sized TiO2 forms was demonstrated. [ABSTRACT FROM AUTHOR]

TiO2 is the most important and remarkable material in photocatalytic applications. In the present work, pure and doped TiO2 nanoparticles were fabricated by the sol‐gel synthesis route. The impact of the metal and nonmetal dopants on the performance of the photocatalysts was examined systematically. X‐ray diffraction (XRD) analysis affirmed the existence of anatase and rutile phases in the fabricated nanoparticles. The diffuse reflectance spectroscopy (DRS) analysis confirmed that all doped TiO2 nanoparticles have a lower bandgap than undoped TiO2, and (N, Cu, Ag)‐doped TiO2 nanoparticles having the lowest bandgap (2.38 eV), demonstrating that metal‐metal‐nonmetal multidoping improves TiO2′s sensitivity towards visible light. In comparison to pure and other doped TiO2 nanoparticles, methylene blue (MB) photodegrades at a faster rate (rate constant of 0.04878 min−1) with the highest photocatalytic activity (99.61 % MB degradation) on the surface of (N, Cu, Ag)‐doped TiO2. The photocatalytic activities of TiO2 nanoparticles have been improved by multidoping in the following sequence: TiO2

Most studies have theoretically and experimentally investigated the effects of single‐element C/N/S doping on the magnetic and photocatalytic properties of three‐dimensional TiO2. However, only a few comparative studies are available on the magnetic and photocatalytic properties of two‐dimensional anatase TiO2 doped with C, N, or S. Based on the density functional theory framework, generalized gradient approximation + U method of the first principles is used to investigate the effects of doping three nonmetallic elements (C/N/S) on the magnetic and photocatalytic properties of bilayer anatase TiO2. The bilayer Ti24O47N (001) is found to have the lowest formation energy, the largest cohesion energy, is relatively stable, and exhibits magnetic property with a magnetic moment of −1.0 μB. The holes and electrons of Ti24O47N (001) system have longest carrier lifetime. The ratio of their average effective masses is 1.28, and the carrier separation in this system is good. The system is most favorable for the preparation of H2 and O2 from water decomposition. Within the 420–790 nm wavelength range, the Ti24O47N (001) system shows the strongest absorption spectrum intensity, the most prominent redshift, and the best activity. Thus, the bilayer Ti24O47N (001) system is an optimal photocatalyst. [ABSTRACT FROM AUTHOR]

The use of pulsed dc‐sputtering sources for reactive magnetron sputtering with oxygen offers a possibility to suppress the negative effects of target poisoning (such as arcing). This results in a wide process range for the selection of a desired operating point. The control of target poisoning plays a major role in maintaining constant coating properties and affects the stoichiometry of the reactive coating, as well as the coating rate and the economic impact of the coating process. In a hysteresis, the target poisoning during the reactive sputtering of titanium under oxygen addition proceeds nonlinearly. Without the use of a suitable target poisoning control technique, the sputtering process can abruptly change to an unstable state. As a result, variations of stoichiometry can occur during the deposition process. A proven method for maintaining a stable reactive sputtering process is the control of oxygen flow with the input variable target voltage. By determining the typical oxygen hysteresis at constant target power and constant argon flow, an operating point for the control loop is derived. The desired target voltage then serves as the input variable for the control loop of the target poisoning. The controlling technique for target poisoning is a basic requirement for the production of the photolytic active anatase phase of titanium dioxide (TiO2) using reactive magnetron sputtering. The photocatalytic equipment of surfaces with a titanium dioxide coating in the anatase phase can be realized with the reactive pulsed dc magnetron sputter ion plating process (DC‐MSIP). The pulsed DC‐MSIP process facilitates coating a variety of surfaces at temperatures below 200°C in an environmentally friendly manner. [ABSTRACT FROM AUTHOR]

Various surface modification strategies are being developed to endow dental titanium implant surfaces with micro- and nano-structures to improve their biocompatibility, and first of all their osseointegration. These modifications have the potential to address clinical concerns by stimulating different biological processes. This study aims to evaluate the biological responses of ananatase-modified blasted/etched titanium (SLA-anatase) surfaces compared to blasted/acid etched (SLA) and machined titanium surfaces. Using unipolar pulsed direct current (DC) sputtering, a nanocrystalline anatase layer was fabricated. In vitro experiments have shown that SLA-anatase discs can effectively promote osteoblast adhesion and proliferation, which are regarded as important features of a successful dental implant with bone contact. Furthermore, anatase surface modification has been shown to partially enhance osteoblast mineralization in vitro, while not significantly affecting bacterial colonization. Consequently, the recently created anatase coating holds significant potential as a promising candidate for future advancements in dental implant surface modification for improving the initial stages of osseointegration. [ABSTRACT FROM AUTHOR]

Copyright of Refractories / Naihuo Cailiao is the property of Naihuo Cailia (Refractories) Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Solar hydrogen production at a high efficiency holds the significant importance in the age of energy crisis, while the micro‐environment manipulation of active sites on photocatalysts plays a profound role in enhancing the catalytic performance. In this work, a series of well‐defined single‐site Ni‐grafted TiO2 photocatalysts with unique and specific coordination environments, 2,2′‐bipyridine‐Ni−O−TiO2 (T−Ni Bpy) and 2‐Phenylpyridine‐Ni−O−TiO2 (T−Ni Phpy), were constructed with the methods of surface organometallic chemistry combined with surface ligand exchange for visible‐light‐induced photocatalytic hydrogen evolution reaction (HER). A prominent rate of 33.82 μmol ⋅ g−1 ⋅ h−1 and a turnover frequency of 0.451 h−1 for Ni are achieved over the optimal catalyst T−Ni Bpy for HER, 260‐fold higher than those of Ni−O−TiO2. Fewer electrons trapped oxygen vacancies and a larger portion of long‐lived photogenerated electrons (>3 ns, ~52.9 %), which were demonstrated by the electron paramagnetic resonance and femtosecond transient IR absorption, correspond to the photocatalytic HER activity over the T−Ni Bpy. The number of long‐lived free electrons injected from the Ni photoabsorber to the conduction band of TiO2 is one of the determining factors for achieving the excellent HER activity. [ABSTRACT FROM AUTHOR]

The spin-coating process was used to create the TiO2 layer successfully. The TiO2 film was created by dissolving TiO2 nanopowder in terpineol and ethylcellulose, and then spin coating it onto the corning glass. The films' shape, phase, and optical properties were then determined using SEM, XRD, and UV-Vis. Photocatalytic measurements of TiO2 films were performed using a UV lamp to irradiate a 12 mg/l methylene blue solution for 5 hours. According to the results, all TiO2 films feature an anatase phase with crystallite size values ranging from 5.55 nm to 6.94 nm and an absorbance region near the UV range. The best photocatalytic activity was found in a film containing TiO2 particles that had been stirred for 5 hours with the value of constant rate of discoloration dye 0.0032/min. [ABSTRACT FROM AUTHOR]

Currently, textile and food industries produce a significant volume of sewages containing azo dyes and other organic pollutants. These effluents are serious environmental threats, so new methods for their treatment and the degradation of azo dyes are attracting much attention. Composite materials based on TiO2 modified by noble metals and nanoceria show high activity in the photodegradation of organic contaminates and are proposed for hydrogen synthesis as well. To optimize the treatment of contaminants, different processes can combine including the strategies of adsorption, photoluminescence, photocatalysis, etc. The synthesized TiO2-based nanomaterials (sols, powders) will be exploited for bioremediation due to their small size and surface plasmon resonance from noble metals. Binary nanocomposites based on TiO2 were obtained by the chemical co-precipitation method from solutions of titanium tetraisopropoxide (TTIP) and inorganic salts of cerium, silver, and palladium. It has been stated that TiO2 is represented by anatase with primary particle size (CSR) from 8.5 to 16.8 nm, depending on the nature and concentration of the dopant. It is shown that Ag is reduced on the surface of anatase particles and blocks their growth, while Pd and Ce penetrate the titanium dioxide matrix in the form of small clusters with the deformation of the anatase crystal lattice. Nanocomposite particles formed loose and fragile aggregates, which spontaneously dispersed in solutions of dyes with the formation of colloid-stable sols, required the use of a centrifugal field for their sedimentation. Nanoparticles of TiO2&Pd were electronegative and others were electropositive according to the values 4.1÷9.6 of ZPC (zero point of charge). It was shown that the particles of all composites sorbed Methylene Blue (MB) without photocatalytic activity under the visible light to any dye. Moreover, anionic dyes such as OrangeG (Or-G) and Methyl Orange (MO) were excellently discolorated in the presence of TiO2&Pd system; cationic dyes of MB and Rhodamine B (RhB) discolorated too with the TiO2, TiO2&CeO2, and TiO2&Ag systems under UV light action. As such, photocatalysis tests showed that Orange-G’s and MO’s discoloration was higher for TiO2&Pd (2 wt. %) and TiO2 systems with the correlation coefficient R² 0.999. [ABSTRACT FROM AUTHOR]

Thin films of Nd-doped TiO2 were fabricated using sol–gel dip-coating. X-ray powder diffractometer, Fourier transform infrared (FTIR) spectroscopy, UV–Vis–NIR spectrophotometer, and LCR meter were used for characterization. The formation of the anatase phase was confirmed by XRD spectra and FTIR spectra. The crystallite size was evaluated by using the Scherer formula that was found to fluctuate between 6.86 and 9.66 nm; it increased from 1 to 4 wt% and then decreased for 5 wt% which is explained in terms of nucleation. The blue shift was observed in transmission spectra with increasing dopant concentration. Antimicrobial testing was carried out against one fungal strain, Aspergillus fumigatus, and four different bacteria S. Aureus, Pseudomonas Aeruginosa, Klebsiella Pneumoniae, and E. coli. 2 and 4 wt% Nd-doped TiO2 showed the highest antibacterial and photocatalytic activity, respectively. The AC conductivity was found to be enhanced by Nd doping. Magnetic analysis reveals that trivalent doping of (Nd3+) ions in the host Ti–O lattice enhanced the ferromagnetic behavior. [ABSTRACT FROM AUTHOR]

In this work, a complete beneficiation technical route combining physical and chemical methods, namely a roasting-flotation-leaching scheme, is proposed to produce a qualified grade Ti-concentrate from altered Vanadium titanomagnetite (VTM) ore. Based on the character of the ore sample, it is recommended to recover the Ti-bearing minerals, ilmenite and anatase, as composite mineral. Pretreatment experiments indicate that the oxidation roasting (800 °C) and acid washing methods increase the flotation indexes significantly. Flotation condition tests show that the optimal conditions are a grinding fineness of −0.045 mm 83%, sulfuric acid dosage of 2000 g/t, water glass dosage of 1500 g/t, oxalic acid dosage of 200 g/t, and EM328 dosage of 1500 g/t. An open flotation circuit test obtains a flotation concentrate with a TiO2 grade and recovery of 38.30% and 25.99%, respectively. A leaching exploration test shows that the TiO2 grade of the flotation concentrate can be improved to 53.90%. XRD analyses reveal that the ilmenite in the VTM ore is converted into anatase and rutile during the roasting process at 600–800 °C, but pseudobrookite begins to form at 900 °C. Compared to the flotation concentrate, it is confirmed that the content of Ti-bearing minerals is increased significantly in the leaching residue. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

We investigated the polaron-assisted nonadiabatic dynamics in protonated TiO2, as well as the polaron-H2O coupling and its effects on the relaxation of photogenerated electrons. We observed that different polaron hopping regimes result in varied nonadiabatic couplings and relaxations of excited electrons from the conduction band minimum to the gap states of protonated TiO2, with a weak dependence on the actual trapping site of the polaron. Surface-adsorbed H2O molecules can attract polarons toward the adsorbed Ti sites, with the coupling between H2O and the polaron being inversely proportional to their distance. Our findings suggest that the lifetime of the photogenerated charge carriers can be extended by reducing the polaron-H2O distances, with expected benefits to the efficiency of the reduced TiO2 samples for photocatalytic applications.

Titanium slag is a by-product of iron extraction from Ilmenite ore. Titanium slag has a high TiO₂ content, so it is a suitable material for preparing TiO₂. This study investigated the influence of the slag particle size on the ability to synthesise TiO₂ by the hydrothermal alkalisation method. Three groups of titanium slag powder with average particle sizes from 18 μm to 108 μm were alkalised with a 10M NaOH solution to separate TiO₂ by the hydrothermal method. The mixing ratio by mass between the slag and the 10M NaOH solution is 1:1.5. The hydrothermal reaction was carried out at 180 °C for 7 hours. The products were analysed for their mineral, chemical, and microstructural properties using X-ray diffraction, X-ray fluorescence, scanning electron microscopy with energy-dispersive detector. The results show that the particle size significantly influences the efficiency of the TiO₂ chemical extraction from the titanium slag. The formed TiO₂ is of high purity, and the main mineral composition is anatase. The anatase polymorph of TiO₂ has the potential application as a photocatalyst and an antibacterial material.

Abstract This study aimed to prepare antifouling and highly mechanical strengthening membranes for brackish and underground water desalination. It was designed from cellulose acetate (CA) loaded anatase. Anatase was prepared from tetra-iso-propylorthotitanate and carboxymethyl cellulose. Different concentrations of anatase (0.2, 0.3, 0.5, 0.6, 0.7, and 0.8)% were loaded onto CA during the inversion phase preparation of the membranes. The prepared membranes were characterized using Fourier Transform Infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM & EDX), mechanical properties, swelling ratio, porosity determination, and ion release. The analysis confirmed the formation of anatase on the surface and inside the macro-voids of the membrane. Furthermore, anatase loading improved the CA membrane’s mechanical properties and decreased its swelling and porosity rate. Also, CA-loaded anatase membranes displayed a significant antibacterial potential against Gram-positive and Gram-negative bacteria. The results showed that the salt rejection of the CA/anatase films as-prepared varies considerably with the addition of nanomaterial, rising from 46%:92% with the prepared membranes under the 10-bar operation condition and 5 g/L NaCl input concentration. It can be concluded that the prepared CA-loaded anatase membranes have high mechanical properties that are safe, economical, available, and can stop membrane biofouling.

[Display omitted] A novel photocatalyst based on Mn-doped carbon-containing TiO 2 layered metastructure has been successfully prepared. For the first time, the exact distance between layers in highly oriented anatase arrays produced with the assistance of PEG 400 was determined. The synthesis of a series of single-phase Ti 1− x Mn x O 2 samples with a layer-ordered anatase structure and a doping degree from 0.0 to 2.0% was first carried out by annealing crystalline NH 4 TiOF 3 together with a Mn- containing precursor in an air atmosphere at 450 °C for 2 h. [ABSTRACT FROM AUTHOR]

[Display omitted] Real-time in situ X-ray analysis was used to shed light on the topotactic transformation of NH 4 TiOF 3 into nanostructured TiO 2 mesocrystals. Specifically, for the system formed in the presence of the PEG-2000 templating polymer, XRD analysis showed that the overall transformation occurs through four separate transitions, consistent with previous reports. The applicability of synchrotron wide-angle X-ray scattering (WAXS) to real-time in situ analysis has enabled precise temperature mapping of these four transitions and the identification of stability boundaries for the first time. [ABSTRACT FROM AUTHOR]

This research aims to evaluate the efficacy of Mouromtseff’s numbers in assessing the thermal transfer performance of titanium oxide (TiO2) nanosized dispersions in convective heat transfer through a pipe. New experimental coefficients of convective heat transfer, thermophysical and rheological characterisation are carried out for TiO2-based nanodispersions in an aqueous propylene glycol 30 vol% mixture at various nanoadditive mass loadings (from 0.25 to 2.0 wt%). Different Mouromtseff’s number formulations, including the Dittus–Boelter and Simons expressions, were obtained from experimental data of thermophysical properties, enabling concise analyses on the prospective improvement of heat transfer in cooling and heating systems. The morphology, particle size, and crystallinity of the anatase TiO2 nanopowder were confirmed, and the stability of the nanofluids with various surfactants was evaluated, with PSS at a 1:4 mass ratio being optimal. Slight increments in thermal conductivity (up to 1.5%) and density (up to 1.3%) with nanoparticle loading were observed, while isobaric heat capacity presents a decreasing trend (less than 13%). Dynamic viscosity increases with higher nanoadditive concentrations, 8.8% for the 2.0 wt% A-TiO2/PG:W 30:70 + PSS 1:4 nanofluid. The employed Dittus–Boelter and Simons expressions correctly predict a worsening of the convective heat transfer, but the percentages diverge slightly from experimental data.

Titania nanoparticles (NPs) find wide application in photocatalysis, photovoltaics, gas sensing, lithium batteries, etc. One of the most important synthetic challenges is maintaining control over the polymorph composition of the prepared nanomaterial. In the present work, TiO2 NPs corresponding to anatase, rutile, or an anatase/rutile/brookite mixture were obtained at 80 °C by an inverse microemulsion method in a ternary system of water/cetyltrimethylammonium bromide/1-hexanol in a weight ratio of 17:28:55. The only synthesis variables were the preparation of the aqueous component and the nature of the Ti precursor (Ti(IV) ethoxide, isopropoxide, butoxide, or chloride). The materials were characterized with X-ray diffraction, scanning/transmission electron microscopy, N2 adsorption–desorption isotherms, FTIR and Raman vibrational spectroscopies, and diffuse reflectance spectroscopy. The synthesis products differed significantly not only in phase composition, but also in crystallinity, textural properties, and adsorption properties towards water. All TiO2 NPs were active in the photocatalytic decomposition of rhodamine B, a model dye pollutant of wastewater streams. The mixed-phase anatase/rutile/brookite nanopowders obtained from alkoxy precursors showed the best photocatalytic performance, comparable to or better than the P25 reference. The exceptionally high photoactivity was attributed to the advantageous electronic effects known to accompany multiphase titania composition, namely high specific surface area and strong surface hydration. Among the single-phase materials, anatase samples showed better photoactivity than rutile ones, and this effect was associated, primarily, with the much higher specific surface area of anatase photocatalysts.

Thin films of pristine titanium dioxide (TiO2) and doped with different concentrations (0–8) at.% of nickel (Ni) were synthesized onto transparent glass substrates using the spray pyrolysis deposition technique. Field emission scanning electron microscopy revealed the porous and agglomerated surface morphology of the films. X-ray diffractometer demonstrated the anatase crystal structure with a nominal increment of (101) peak. The shifting of peak position revealed the expansion of the unit cell volume from 134.64 to 137.54 (Å)3 whereas crystallite size increased from 34 to 63 nm. Using the Fizeau fringes technique, the thickness of the films was determined between 165 and 190 nm. UV–Vis measurements were employed to examine the optical characteristics of the films. The red shift was observed for 2 at.% Ni content (3.38 eV) while the blue shift was observed for (4–8) at.% Ni content. The wavelength-dependent refractive index and dielectric constant showed anomalous dispersion in the absorption band, representing the transparency of the films. The 4-point probe measurement showed a decreasing trend of resistivity with increasing temperature, whereas the resistivity increased with Ni content. Activation energy indicated a higher amount of adsorbed oxygen in the films due to the high amount of Ni content.

TiO2 is one of the most important metal oxides which are widely applied in various fields, and the modifications of synthesis process and in-depth characterization are growing up day by day. Nano Anatase and Rutile phases of TiO2 were synthesized from titanium iso-butoxide following an easy approach where no toxic chemicals were utilized. Nano-TiO2 (Rutile phase) was synthesized from the thermal conversion of the nano-Anatase phase (which was obtained at room temperature) at 700 °C temperature for 2 h. Anatase and Rutile phases were confirmed by the X-ray diffraction (XRD) data and matched with the standard database. Different crystallographic parameters such as lattice parameters, and preference growth were calculated from the XRD data. Different methods were utilized to estimate the crystallite size of the Anatase and Rutile phase of TiO2 by using the Scherrer equation, Williamson-Hall plot, Monshi-Scherrer Model, Size-strain plot method, Halder- Wagner Model, and Sahadat-Scherrer Model. All the models presented crystallite size in the accepted region, and linear regression coefficients were also taken into consideration. In addition to the crystallite size, various intrinsic parameters such as stress, strain and energy density were also computed from the mentioned models based on XRD.

Recently, TiO2(B) has been extensively used in catalytic and energy fields owing to its exceptional crystal structure. But being a metastable state, TiO2(B) is transformed easily into other stable crystalline forms like anatase or rutile phase, and the low crystallinity limits the application of the material in catalysis. A combination of TiO2(B) with anatase, which is benefitted by a homojunction, is proven to be blessed with high activity. Herein, hydrogen production via photocatalytic water-splitting is presented using Cu modified biphasic titania nanotubes achieved by a facile hydrothermal procedure. The systems are well characterized using SEM, TEM, XRD analysis, N2 adsorption study, FTIR, DR-UV, Raman, Photoluminescence, and X-ray photoelectron spectral analysis. The homo-junction developed in titania due to anatase –TiO2 (B), as well as the heterojunction created by the co-catalyst, tune the photocatalytic activity of TiO2 nanotubes positively, as evident from the enhanced hydrogen production over the system.

The photocatalytic selective reduction of 3‐nitrophenol to 3‐aminophenol was studied in the presence of titanium dioxide in the form of various anatase and rutile compositions. The reaction progress is altered by various parameters, which can be classified as intrinsic (depending on the chemical, structural, and electronic features) and extrinsic (depending on the reaction and conditions). The goal of the studies was to understand the influence of intrinsic factors and to compare the performance of anatase and rutile materials. The (photo)electrochemical analysis revealed unequivocally the differences in interfacial electron transfer, charge recombination, reduction driving force, and methanol photooxidation efficiency for titania polymorphs. It appeared that all mentioned processes were phase‐dependent, and they contributed unequally to overall photocatalytic activity. In particular, methanol oxidation was the most efficient at the rutile phase, which overcame the critical limitation of the oxidation pathway and facilitated the reduction of 3‐nitrophenol. On the other hand, the dark electron transfer efficiency was highest at the anatase phase, despite the lower driving force in this case. The presented thorough and systematic analysis of the discussed photocatalytic system (the photocatalyst and the reaction) should allow the rational design of efficient and selective photocatalysts. [ABSTRACT FROM AUTHOR]

TiO2/graphene oxide (GO) nanocomposites with high contact interface were prepared with glycol 400 (PEG400) served as dispersant. This nanocomposite exhibits improved photocatalytic efficiency in contrast with the nanocomposite prepared without PEG400. In this work, the photocatalytic performance was investigated by observing the degradation rate of Rhodamine B (RhB). And it is found that the mass ratios of GO in nanocomposites plays an important role. When the mass ratio of GO reached 45%, the photocatalytic performance of the nanocomposites reached the highest, which is ∼72%. Moreover, the photocatalytic mechanism was studied through theoretical calculations, which can be summarized as follows: (1) the presence of GO decreases the band gap of TiO2 nanoparticles. (2) GO inhibits the the recombination of photogenerated electron–hole pair. (3) GO improves the adsorption capacity of TiO2 nanoparticles for RhB. This work promoted the application of TiO2/GO nanocomposites in wastewater treatment. [ABSTRACT FROM AUTHOR]

The photoelectrochemical properties of titanium dioxide (TiO2) nanoparticles are directly related to the presence of certain facets. The synthesis of such particles is challenged using volatile and sensitive precursors utilizing shape capping agents. In this study, an easier two‐step synthesis technique for the preparation of well‐specified morphology TiO2 nanocrystals from TiO2 powder is demonstrated. The facet‐dependent Fermi level and flat band potential of the prepared particles are calculated and their photoelectrochemical properties are investigated by Cu2+ and Pb2+ photo/electrodeposition. From Cu2+ electrodeposition, it is shown that the presence of {100} and {001} facets in cubic morphology facilitates the electrodeposition with progressive nucleation mechanisms, while the presence of {101} facet in octahedral geometry follows instantaneous nucleation mechanisms. The activity of electroreduction is also related to the flat‐band potential which shows the highest activity in Pb2+ electrodeposition for octahedron nanostructure due to the alignment of the reduction potential to the edge of the flat band. Photodeposition of Cu2+ and Pb2+ ions shows identical trends to electrodeposition indicating the facets influence in ion adsorption and structure of the bandgap of morphological TiO2. The findings emphasize the importance of facet‐dependent surface adsorption and bandgap structure designing faceted TiO2 nanoparticles for tailored applications. [ABSTRACT FROM AUTHOR]

The thermal conductivity of epoxy nanocomposites filled with self-assembled hybrid nanoparticles composed of multilayered graphene nanoplatelets and anatase nanoparticles was described using an analytical model based on the effective medium approximation with a reasonable amount of input data. The proposed effective thickness approach allowed for the simplification of the thermal conductivity simulations in hybrid graphene@anatase TiO2 nanosheets by including the phenomenological thermal boundary resistance. The sensitivity of the modeled thermal conductivity to the geometrical and material parameters of filling particles and the host polymer matrix, filler's mass concentration, self-assembling degree, and Kapitza thermal boundary resistances at emerging interfaces was numerically evaluated. A fair agreement of the calculated and measured room-temperature thermal conductivity was obtained. [ABSTRACT FROM AUTHOR]

A number of semiconducting and bioactive nanocomposite systems based on TiO2 are designed for environmental protection. The presented structures based on titanium dioxide, formed in binary and ternary systems in the presence of gold, silver, cerium and iron with a different degree of crystallinity, were obtained by sol–gel method using titanium tetraisopropoxide (TTIP) as a precursor species. X-ray diffraction data confirmed a homogeneous composition of powders formed in binary systems (anatase modified with clusters of Au, Ag, and CeO2) and a heterogeneous composition of ternary systems with CSR in the range of 9–20 nm. As such, the XRD of the powders indicated the formation of heterogeneous structures: anatase—cerium dioxide—silver and anatase/brookite—hematite—gold or brookite—gold. Noble metals (Au, Ag) can be used to fill surface traps by donating electrons into 3d states of coordinated Ti ions. It was shown that the ternary composite TiO2-CeO2-Ag (2 wt.%) has improved photocatalytic properties due to the inclusion of CeO2 in the crystal lattice of anatase, which is confirmed by an increase in the degree of tetragonality of the lattice from 2.50 to 2.53, and prevention of oxidation of silver clusters on the surface of anatase under the influence of UV irradiation (98.4%). The photocatalytic efficiency was assessed through the removal and degradation of malachite green. More than 95% of dye solution was decolorized after 5 min of contact with all composites compared to pure TiO2 phase. Thus, the obtained structures are promising materials for creating photoactive catalysts to neutralize malachite green solutions. [ABSTRACT FROM AUTHOR]

The surface of TiO2 nanoparticles was modified with silica prepared by acid hydrolysis of tetraethoxysilane followed by polycondensation. A comparative characterization of the initial and modified nanoparticles by TEM, XRD, specific surface area and ζ-potential measurements as well as the estimation of the surface acid-base properties via dynamic pH measurements revealed that the applied surface modification provided almost no changes in the phase composition, crystallite size range (~16 nm) and mesostructure of the initial anatase nanoparticles, but resulted in a more than twofold increase in the specific surface area and change of the surface functionality from a prominent Lewis acidity toward a relatively weak Broensted acidity. The resulting TiO2@SiO2 "core-shell" particles are shown to exhibit a significant enhancement of singlet oxygen generation compared with the initial TiO2. In conjunction with increased specific surface and modification of the surface centers, this effect promoted a drastic growth of photocatalytic activity indicated by an almost 90% degradation of methylene blue dye upon UV irradiation. Highlights: The surface modification of TiO2 NPs with SiO2 did not cause any phase composition changes. SiO2 shell formation led to a significant decrease in the size NPs and their agglomerates. The formation of SiO2 shell resulted in a more than double increase in the NPs specific surface area. The ТiO2@SiO2 composite nanoparticles are characterized by a higher surface-fractal dimension. SiO2 shells improve the stability of the aqueous suspensions of TiO2 NPs. [ABSTRACT FROM AUTHOR]

In this study, the reaction pathways for the thermal decomposition of formic acid on the anatase TiO2 (101) surface were systematically investigated. The investigation was carried out using a single‐component artificial force induced reaction method that combines density functional theory calculations. In order to uncover the overall mechanism at low surface coverage, we explored reaction path networks for three different conditions of the anatase TiO2 (101) surfaces: clean, protonated, and oxygen‐deficient surfaces. Previous temperature‐programmed desorption (TPD) experiments had shown that H2O desorption starts at a low temperature of about 300 K, while CO and formaldehyde desorption starts at high temperatures of about 500 K. The present reaction path networks are consistent with the overall trend observed in the TPD experiments. Using the reaction pathways extracted from these networks, the overall dissociation mechanism has been discussed. [ABSTRACT FROM AUTHOR]

Titanium dioxide (TiO2) nanoparticles have been extensively studied for catalyzing the photo-degradation of organic pollutants, the photocatalyst being nonselective to the substrate. We, however, found that TiO2 nanoparticles prepared via the sol-gel and hydrothermal synthetic routes each possess a definite specificity to the charge of the substrate for photodegradation. The nanoparticles were characterized by SEM, FTIR, XRD, TGA, and UV-visible spectra, and the photocatalytic degradation under UV-B (285 nm) irradiation of two model compounds, anionic methyl Orange (MO) and cationic methylene blue (MB) was monitored by a UV-visible spectrophotometer. Untreated sol-gel TiO2 nanoparticles (Tsg) preferentially degraded MO over MB (90% versus 40% in two hours), while after calcination at 400 °C for two hours (Tsgc) they showed reversed specificity (50% MO versus 90% MB in one hour). The as-prepared hydrothermal TiO2 nanoparticles (Tht) behaved in the opposite sense of Tsg (41% MO versus 91% MB degraded in one and a half hours); calcination at 400 °C (Thtc) did not reverse the trend but enhanced the efficiency of degradation. The study indicates that TiO2 nanoparticles can be made to degrade a specific class of organic pollutants from an effluent facilitating the recycling of a specific class of pollutants for cost-effective effluent management. [ABSTRACT FROM AUTHOR]

The use of phase change materials (PCMs) for thermal storage, thermal management, and thermal insulation has been widespread for many years. Thermal storage systems (TES) based on PCMs can be improved and optimized by adding nanoparticles (NPs) to them. Throughout this study, PCM nanocomposites (NCs) based on paraffin wax (PW) loaded by anatase titania (TiO2) NPs were fabricated and characterized to examine their thermal performance as phase change materials. The as-synthesized TiO2 NPs were obtained by hydrolysis technique and showed a well-defined spherical shape with a diameter in the nanoscale range and a crystallite size ~ 22.75 nm. Throughout the used concentrations of TiO2 NPs, 0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, and 0.5%, the morphological feature for the PW/TiO2 NCs revealed a good dispersion of NPs in PW. The non-isothermal differential scanning calorimetry (DSC) measurements at a constant heating rate of 10 °C min−1 were used in order to get the melting point (Tm), latent heat of fusion (LH), and latent heat rate (LHR) as a function of TiO2 NP concentrations for the investigated PW/TiO2 NCs. Both LH and LHR values for PW/TiO2 NCs are higher than those obtained for a pure PW sample. The significant enhancement in LH and LHR values for PW/TiO2 NCs was found to be 21.2% and 134.3% in comparison with the pure PW sample, respectively. The thermal stability of the investigated PW/TiO2 NCs was examined using thermal gravimetric (TG) scans. It is found that the thermal stability varies with TiO2 NP concentrations with a non-monotonic trend. At concentrations up to 0.25 mass%, the thermal stability improved. For concentrations over 0.25 mass%, the degradation process became rapid. [ABSTRACT FROM AUTHOR]

We investigated the polaron-assisted nonadiabatic dynamics in protonated TiO2, as well as the polaron-H2O coupling and its effects on the relaxation of photogenerated electrons. We observed that different polaron hopping regimes result in varied nonadiabatic couplings and relaxations of excited electrons from the conduction band minimum to the gap states of protonated TiO2, with a weak dependence on the actual trapping site of the polaron. Surface-adsorbed H2O molecules can attract polarons toward the adsorbed Ti sites, with the coupling between H2O and the polaron being inversely proportional to their distance. Our findings suggest that the lifetime of the photogenerated charge carriers can be extended by reducing the polaron-H2O distances, with expected benefits to the efficiency of the reduced TiO2 samples for photocatalytic applications. [ABSTRACT FROM AUTHOR]

The annealing of amorphous TiOx films obtained by electron-beam evaporation under atmospheric conditions at temperatures from 300 to 400°C is found to lead to the formation of an anatase crystalline phase. According to Raman spectroscopy data, the increase in the fraction of the crystalline phase stops at an annealing temperature above 350°C. According to the results of X-ray diffraction analysis, the average crystallite diameter is about 23 nm. Electron-microscopy studies show that, upon annealing, the surface layer (15 nm thick) crystallizes in the films, and TiO2 nanocrystals with sizes from 4 to 10 nm are formed in the bulk. As the depth increases, the number of nanocrystals decreases. [ABSTRACT FROM AUTHOR]

This research describes the influence of two types of particles, namely rutile and anatase microparticles (average d < 5 µm), on the morphology, structure, and anticorrosive properties of PEO coatings on titanium produced in an alkaline solution based on NaOH and sodium metasilicates. The paper reports the experimental results relating to the study of the influence of the electrical regime and working frequency of the anodizing treatment on the interaction between the particles, the substrate, and the oxide to determine the optimal conditions that favour the incorporation of the particles and the production of a thick oxide. PEO coatings are characterized by using a scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) analysis, and X-ray diffraction (XRD) testing. The electrochemical behaviour is evaluated by free corrosion potential monitoring and electrochemical impedance spectroscopy analysis (EIS) performed in a sulphuric acid solution. The particles are successfully incorporated into the coating under any electrical condition and at any frequency. However, only treatments carried out at 1000 Hz allow the production of coatings that combine a large thickness (up to 50 µm) and improved anticorrosion behaviour. In contrast, oxide layers produced at 20 Hz and in DC show a quite damaged structure, affecting their anticorrosion behaviour and resulting in lower corrosion potential and impedance values. [ABSTRACT FROM AUTHOR]

In this experimental work, homogeneous nanotube layers were successfully formed by anodization on titanium wires with diameters lower than 200 µm employing an aqueous anodizing solution composed of carboxymethylcellulose and sodium fluoride. Homogeneous nanotube layers were formed only when the titanium wires were electropolished. After heat treatment at 350 and 600°C, the nanotubes were transformed from amorphous phase into anatase phase or a mix between anatase and rutile phases. After both heat treatments, the nanotube coatings remained uniform; namely, no apparent cracks, critical defects, or coating delamination were seen. To the best of our knowledge, a homogeneous nanotube coating composed of anatase or a mix between anatase and rutile phases on titanium wires with diameters lower than 200 µm has not been reported. These coatings may be potentially useful in a variety of fields, including biomedicine, sensing, and catalysis. [ABSTRACT FROM AUTHOR]

This study aimed to prepare antifouling and highly mechanical strengthening membranes for brackish and underground water desalination. It was designed from cellulose acetate (CA) loaded anatase. Anatase was prepared from tetra-iso-propylorthotitanate and carboxymethyl cellulose. Different concentrations of anatase (0.2, 0.3, 0.5, 0.6, 0.7, and 0.8)% were loaded onto CA during the inversion phase preparation of the membranes. The prepared membranes were characterized using Fourier Transform Infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM & EDX), mechanical properties, swelling ratio, porosity determination, and ion release. The analysis confirmed the formation of anatase on the surface and inside the macro-voids of the membrane. Furthermore, anatase loading improved the CA membrane's mechanical properties and decreased its swelling and porosity rate. Also, CA-loaded anatase membranes displayed a significant antibacterial potential against Gram-positive and Gram-negative bacteria. The results showed that the salt rejection of the CA/anatase films as-prepared varies considerably with the addition of nanomaterial, rising from 46%:92% with the prepared membranes under the 10-bar operation condition and 5 g/L NaCl input concentration. It can be concluded that the prepared CA-loaded anatase membranes have high mechanical properties that are safe, economical, available, and can stop membrane biofouling. [ABSTRACT FROM AUTHOR]

In this study, a titanium oxide-nitride coating was applied to 12Cr18Ni10Ti stainless biomedical steel through reactive magnetron sputtering deposition. The microstructure and chemical bond evolution during film sputtering was tested using different flow rates of oxygen and argon, namely N 2 /O 2 ratios of 1, 1.5, and 2. The obtained samples were analysed by IR spectroscopy, SEM, XPS, and XRD. In addition, the nanoindentation procedure measured the hardness and elastic modulus of each coating. Oxynitride coatings exhibit nanocrystalline structures, where the nitride and oxide phases are in the unbound state. A nitrogen-rich sample demonstrated the crystalline structure of (110)-oriented rutile with 124 nm large clusters. However, with increased oxygen gas flow, the mixed rutile-anatase (111)-oriented phase became more pronounced with fragmented grains 25–27 nm in diameter. The nanoindentation test shows that titanium oxide hardness and deformation resistance depend on its microstructure and orientation. Cell culture experiments show that a coating deposited at regime N 2 /O 2 = 1 allows efficient cell proliferation on pristine steel and other oxynitride samples. The findings of this work benefit understanding the mechanisms of oxynitride barriers in coronary stent modification. [Display omitted] [ABSTRACT FROM AUTHOR]

Goethitic bauxite is a widely used raw material in the alumina industry. It is an essential prerequisite to clarify the effect of Ti- and Si-containing minerals on goethite transformation in the Bayer digestion process, which could efficiently utilize the Fe- and Al-containing minerals present in goethitic bauxite. In this work, the interactions between anatase or kaolinite with goethite during various Bayer digestion processes were investigated using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The results showed that anatase and kaolinite hindered the transformation of goethite. Anatase exerted more significant effects than kaolinite due to the dense sodium titanate layer on the goethite surface after reacting with the sodium aluminate solution. Adding the reductant hydrazine hydrate could eliminate the retarding effect by inducing the transformation of goethite into magnetite. In this process, titanium was embedded into the magnetite lattice to form Ti-containing magnetite. Furthermore, the weakening of the interaction between magnetite and sodium aluminosilicate hydrate reduced the influence of kaolinite. As a validation of the above results, the reductive Bayer method resulted in the transformation of goethite into goethitic bauxite with 98.87% relative alumina digestion rate. The obtained red mud with 72.99wt% Fe2O3 could be further utilized in the steel industry. This work provides a clear understanding of the transformative effects of Ti- and Si-containing minerals on iron mineral transformation and aids the comprehensive use of iron and aluminum in goethitic bauxite subjected to the reductive Bayer method. [ABSTRACT FROM AUTHOR]

TiO2-Al2O3 supports with different incorporation methods of titania were synthesized via three methods: impregnation (TA-I), co-precipitation (TA-CP), and co-precipitation–hydrothermal treatment (TA-HT). And the NiMoP catalysts prepared on the corresponding supports were evaluated for hydrodesulfurization (HDS) reactions. The results demonstrated that the Ti atoms in TA-I are attached to alumina through hydroxyl groups, while the Ti atoms in TA-CP and TA-HT can be dispersed in the alumina skeleton. Variations in the incorporation modes of TiO2 affect the support properties, consequently influencing the nature of the active metal on the supports. The Ti atoms dispersed in the Al2O3 skeleton allow an increase in the basic hydroxyl groups. Meanwhile, TiO2 in TA-CP and TA-HT can absorb hydrogen molecules and be partially reduced. Furthermore, metal species supported on the TA-CP and TA-HT are more easily reduced and better dispersed. For the NiMoP catalysts prepared with TA-CP and TA-HT, the Ti element promotes the sulfidation degree of Mo, besides shortening the average (Ni)MoS2 slab. The catalysts prepared with TA-CP exhibited superior activity for 4,6-DMDBT hydrodesulfurization. This can be ascribed not only to the relatively high sulfidation degree of Mo and proportion of the NiMoS active phase but also to the well-dispersed (Ni)MoS2 slabs. Moreover, the Ti4+ ions dispersed in the Al2O3 skeleton can be partially reduced to act as electron donors, enhancing the metallic character of the S layers in MoS2, which facilitates the improvement of the hydrogenation desulfurization activity.

Abstract The photoelectrochemical properties of titanium dioxide (TiO2) nanoparticles are directly related to the presence of certain facets. The synthesis of such particles is challenged using volatile and sensitive precursors utilizing shape capping agents. In this study, an easier two‐step synthesis technique for the preparation of well‐specified morphology TiO2 nanocrystals from TiO2 powder is demonstrated. The facet‐dependent Fermi level and flat band potential of the prepared particles are calculated and their photoelectrochemical properties are investigated by Cu2+ and Pb2+ photo/electrodeposition. From Cu2+ electrodeposition, it is shown that the presence of {100} and {001} facets in cubic morphology facilitates the electrodeposition with progressive nucleation mechanisms, while the presence of {101} facet in octahedral geometry follows instantaneous nucleation mechanisms. The activity of electroreduction is also related to the flat‐band potential which shows the highest activity in Pb2+ electrodeposition for octahedron nanostructure due to the alignment of the reduction potential to the edge of the flat band. Photodeposition of Cu2+ and Pb2+ ions shows identical trends to electrodeposition indicating the facets influence in ion adsorption and structure of the bandgap of morphological TiO2. The findings emphasize the importance of facet‐dependent surface adsorption and bandgap structure designing faceted TiO2 nanoparticles for tailored applications.

Microbial fuel cells (MFC) have considerable potential in the field of energy production and pollutant treatment. However, a low power generation performance remains a significant bottleneck for MFCs. Biochar and anatase are anticipated to emerge as novel cathode catalytic materials due to their distinctive physicochemical properties and functional group architectures. In this study, biochar was utilized as a support for an anatase cathode to investigate the enhancement of the MFC power generation performance and its environmental impact. The results of the SEM and XPS experiments showed that the biochar-supported anatase composites were successfully prepared. Using the new cathode catalyst, the maximum current density and power density of the MFC reached 164 mA/m2 and 10.34 W/m2, respectively, which increased by 133% and 265% compared to a graphite cathode (70.51 mA/m2 and 2.83 W/m2). The degradation efficiency of Cr (VI) was 3.1 times higher in the biochar-supported anatase MFC than in the graphite cathode. The concentration and pH gradient experiments revealed that the degradation efficiency of Cr (VI) was 97.05% at an initial concentration of 10 mg/L, whereas a pH value of two resulted in a degradation efficiency of 94.275%. The biochar-supported anatase composites avoided anatase agglomeration and provided more active sites, thus accelerating the cathode electron transfer. In this study, natural anatase and biochar were ingeniously combined to fabricate a green and efficient electrode catalyst, offering a novel approach for the preparation of high-performance positive catalysts as well as a sustainable, economical, and environmentally friendly method for Cr (VI) removal in aqueous solutions. [ABSTRACT FROM AUTHOR]