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Alumina–titania (Al2O3/TiO2) composites are well-known for their physical and microstructural properties, which allow several engineering applications. However, these properties change when different sintering temperatures are used, due to the existence of two antagonistic phenomena (grain coarsening versus densification) that occurs during sintering process. The aim of this study was to evaluate the microstructural and physical properties of the alumina–titania composites and to understand these two antagonistic phenomena when different partial sintering temperatures are used. The composites were prepared from alumina and titania powders by uniaxial pressing and sintered at different temperatures (1100–1400 °C). The structural analysis showed that in addition to expected phases (α-Al2O3 and rutile), the alumina–titania composite sintered at 1100 °C presents anatase phase, while those obtained at 1300 and 1400 °C present tialite phase. The morphology analysis revealed a random distribution of grains with irregularly shaped pores. According to the Archimedes-based immersion test, all composites have a relative bulk density ranging 60.43–73.59%, showing that none of them reached the final sintering stage. Statistical analysis revealed that the average grain size of the matrix ranges from 3.62 to 5.24 μm. Moreover, the statistical analysis also showed that the grain coarsening predominates over densification for the composites sintered from 1100 to 1150 °C. The densification predominates over grain coarsening for the composites sintered from 1150 to 1200 °C, and from 1250 to 1400 °C. The two phenomena coexist only for the composites sintered from 1200 to 1250 °C.

In this study, we prepared chitosan (Cs_P) nanofibers (NFs) membrane by electrospinning. The Cs_P NFs membrane was then chemically functionalized (CsF) by a novel stepwise chemical process. The CsF NFs membrane was electrospray with TiO2 nanoparticles (NPs) to prepare the CsF_Coa NFs membrane. A second NFs membrane with embedded TiO2 NPs (Cs_Co) was also prepared by electrospinning. The TiO2 NPs, Cs_P, CsF s, CsF_Coa NFs, and Cs_Co NFs membranes were analyzed by standard spectroscopic, microscopic, X-ray, and thermal methods. Fourier transform infrared (FTIR) analysis confirmed the incorporation of the new functional group into the Cs structure. X-ray photoelectron spectroscopy (XPS) data confirmed the FTIR results and the fabrication of the CsF NFs membrane. Scanning electron microscope (SEM) micrographs showed a smooth morphology for the Cs_P NFs membrane and a denser morphology for the CsF NFs membrane (NFs swelled with functionalization). The SEM micrographs also showed a dense cloud of TiO2 NPs on the surface of the Cs_Coa NFs membrane. Transmission electron microscope (TEM) showed that the particle size of TiO2 NPs varied between 20 and 35 nm and tended to be spherical. The X-ray diffraction (XRD) pattern confirmed the existence of the anatase phase of the TiO2 NPs. The presence of TiO2 in the Cs_Coa and Cs_Co NFs membranes was also confirmed by energy-dispersive x-ray spectroscopy (EDX). Surface profilometry confirmed an increase in the surface roughness of the CsF and Cs_Coa NFs membranes. Brunauer–Emmett–Teller (BET) analysis revealed that the isotherms and hystereses for all NFs membranes were of the IV and H3 types, respectively, corresponding to mesopores and slit pores. The higher photocatalytic activity of the Cs_Coa NFs membrane (89%) compared to the Cs_Co NFs membrane (40%) was attributed to a balance between the short band gap, high surface roughness, and lower surface area.

Anatase TiO2 nanotubes array (ATONA) has attracted tremendous attention owing to its promising applications in solar cells, water splitting and organic pollutants photocatalytic degradation. However, the activity of ATONAs was greatly suppressed by the grain boundaries existed in the tube walls, which acted as carrier scattering and recombination centers. Herein, we report a novel strategy to prepare array of single crystalline anatase TiO2 nanotubes (SC-ATONAs) with significant enhancement of the photocatalytic activity and UV photo response performance compared to the polycrystalline counterparts. The growth of SC-ATONAs was achieved by establishing a crystallization temperature gradient along the tube wall, which ensured the crystallization started from the nucleation of a single nucleus at the bottom of amorphous TiO2 nanotubes prepared by Ti anodization. These findings pave the way to prepare single-crystalline nanotubes with superior performance for other materials.

A visible light responding TiO2 photocatalyst was prepared by the hydrolysis of TiCl4 with ammonia. Its structures were characterized to anatase with doping of oxynitride by XRD and XPS followed by drying and heat treatment at 400 °C for 2 h (TiON400). The primary particle size observed by TEM was ~10 nm, and the BET surface area was 320 m2/g. Photocatalytic degradation of trichloroethylene (TCE) over TiON400 under blue light emitting diode (BLED) and violet light emitting diode (VLED) irradiation was tested using a Fourier transform infrared (FTIR) spectrometer. The collected FTIR spectra verified the decrease in TCE concentration and the formation of intermediates such as dichloroacetyl chloride (DCAC) and COCl2 during the photocatalysis of TCE. It is concluded that in-situ FTIR analysis can be a useful and reliable tool to evaluate the photocatalytic performance of materials. A new ISO standard for photocatalysis testing method with FTIR analysis under ultraviolet, visible, or violet irradiation is possible to propose.

TiO2 samples with different crystal sizes and compositions were synthesized using a sol-gel method at different calcination temperatures (350–900 °C). The activity and stability of TiO2 samples were determined by the gasification of formaldehyde in supercritical water (SCW) and by treatment in SCW. Increasing calcination temperature and SCW gasification (SCWG)/SCW treatment decreased the surface area of anatase TiO2 samples due to growing crystallite size via agglomeration and sintering. Among anatase TiO2 samples, the TiO2 calcinated at 450 °C was found as the most suitable material under SCW conditions. However, the surface area of rutile TiO2 slightly increased from 17.2 m2 g−1 to 19.8 m2 g−1 with the weakly crumbling of particles during SCWG. The highest hydrogen formation (63%) from formaldehyde in the SCW was obtained in the presence of anatase TiO2 calcined at 350 °C and rutile TiO2 calcined at 800 °C. CO2 formation in the presence of anatase TiO2 is higher than rutile TiO2 because of the presence of active lattice oxygen species (O−, O2−) based on O2-TPD., This study was supported by the Scientific and Technological Research Council of Turkey (TUBITAK), Turkey (Grant No.213M398).

Pure TiO2 anatase semiconductor materials with three different morphologies (nanoparticles, nanotubes and nanofibers) were used to disperse with PtOx (2.0 wt.% nominal loading) nanoparticles. Structural, electronic and morphological characteristics of the calcined materials were studied by using XRD, Raman, DR UV–vis, XPS spectroscopy, transmission electron microscopy and N2 physisorption techniques. The band gap energy values were obtained from the Tauc plots and band gap energy values were decreased after deposition of PtOx over TiO2 nanomaterials. PtOx-TiO2 anatase nanotubes (2.0 Pt–Ti-A-NT) sample possessed unique physico-chemical properties such as high Pt dispersion, high surface area, pore volume and pore diameter in the range of 10–40 nm with unimodal distribution. The photocatalytic performances of all synthesized samples were tested for hydrogen production via reforming of aqueous methanol under visible light irradiation. To optimize the reaction conditions, several parameters such as methanol concentration, mass of the catalyst, pH of solution and reaction temperature were studied. Among the synthesized samples, 2.0PtOx-TiO2 anatase nanotubes sample exhibited highest photo activity for hydrogen generation. The observed results indicated the significant role of the morphology of TiO2 anatase semiconductor; decrease of the band gap energy, increasing electron storage and delayed electron–hole recombination due to high interaction between PtOx and TiO2 nanotubes. The highest performance for 2.0 PtOx-TiO2 anatase nanotubes sample at a promising hydrogen quantity of 1489 μmolg−1 was observed at 50 °C after 3 h.

Influence of nitrogen precursors urea, semicarbazide and N,N’-dimethyl urea on the photocatalytic activity of the N-doped TiO2 were studied by a simple decomposition method. The nano N-TiO2 catalysts were synthesized via two different modified approaches by calcination at 500 oC. The synthesized samples were characterized by IR, UV-DRS, Raman, TG-DTA, XRD, EDX, XPS, SEM, TEM and BET analysis. Of the synthesized six samples of N-TiO2 five samples showed better photocatalytic activity towards direct sunlight photo-degradation of methylene blue (MB) and rhodamine B (RhB) than Degussa P25. The catalysts obtained using semicarbazide samples F3 and F4 having large surface area of 76 and 85.8 m2/g displayed maximum photocatalytic activity. The sample F4 was 1.5 times more active than Degussa P25 for the decolourisation of MB and 1.9 times more active for the decolourisation of RhB. The presence of nitrogen, large surface area and coupling of rutile-anatase phases were found to be the main responsible factors for the enhanced photocatalytic activity. The exclusive formation of the anatase phase in the case of urea precursor is attributed to the slow evaporation of urea due to the formation of melamine derived products. The calcination temperature is the deciding factor responsible for the photocatalytic activity of the N-TiO2 samples prepared from precursors which can potentially form the melamine and its oligomerized products on the surface of TiO2.

In the paper, impact of the precursor decomposition conditions on the morphological and structural characteristics of TiO2 particles was discussed. The novelty and significance of the researches lay in the ability to control morphological features of the synthesized powder particles so that enhanced properties of the sintered ceramics can be obtained. The research program covered thermal decomposition of titanium nitrate, titanium oxyfluoride and titanium oxysulphate at different temperatures, with and without organic additive. Obtained titanium dioxide powder underwent analysis, namely, its phase composition, particle shape and dimensions were measured using X-ray and IR-spectra, as well as scanning electron microscopy. Activity of the obtained particles during sintering process was analyzed using dilatometer and microhardness measurement after sintering. It was found that spherical TiO2 nanoparticles of anatase and rutile phases can be obtained from decomposition of titanium nitrate at 700 °C. Thermal decomposition of other precursors, titanium oxyfluoride and oxysulfate, synthesized only anatase phase with particles of 200 and even 300 nm. Obtained spherical particles were smaller when temperature of decomposition was lower or the activator OP9 was added. However, lower decomposition temperature and additive had negative effect on sintering activity of the obtained particles, decreasing the microhardness of sintered specimens.

The present study deals with the gel formation tendency in the ternary TeO2-TiO2-ZnO system. Depending on the TiO2 amount, the gelation occurred at different times and subsequently several gel formation regions have been determined. Homogeneous, transparent and monolithic gels were obtained using combination of organic and inorganic precursors during the synthesis. Using XRD analysis it was established that upon the heating composites were obtained which contain an amorphous phase and different crystalline phases: TiO2 (anatase), TiO2 (rutile), α-TeO2 and ZnTeO3, depending on composition. The IR results showed that the short range order of the amorphous phases which are part of the composite materials consist of TiO6, ZnO4 and TeO4 structural units. Using UV–Vis spectroscopy it was established that the absorption edge of the gels varied from 330 nm to 364 mm and the increase in TiO2 content caused a red shifting of the cut-off. The calculated Eg values are in the range 3.41–3.75 eV higher than that of pure TiO2, TeO2 and ZnO oxides. The XPS results showed that the Te atoms in the surface layers of the samples studied exist in several chemical states as Te2+, Te0, but Te6+ dominates. Octahedrally coordinated Ti4+ ions are observed in the gels and in the samples annealed at 200 °C but a small amount of tetrahedrally coordinated Ti4+ is also detected, which indicates the incomplete polymerization of TiO6 units.

The influence of cyanuric acid (CA) on the structural, textural, electronic, morphological properties and the photocatalytic activity of titanium dioxide materials (TNCA) were herein evaluated. TNCAs samples were prepared through the sol gel method. The novelty of this work that cyanuric acid; the so far most recalcitrant molecule, is used here as reservoir of nitrogen. The synthesis of TNCAs nanomaterials are performed at low temperature in presence of quaternary ammonium as co-catalyst for anatase growth. Samples were characterized by means of nitrogen adsorption-desorption isotherms at 77 K, X-ray diffraction (XRD), Infrared (ATR), Raman, diffuse reflectance ultraviolet-visible, photoluminescence (PL) and electron paramagnetic resonance (EPR) spectroscopies, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The photocatalytic activities of TNCAs and their free counterpart nanomaterials were then evaluated in the photocatalytic degradation of formic acid (FA) as model molecule under UV.X-ray and Raman show success of anatase phase formation at low temperature without any post-calcination. IR-ATR analysis confirms CA grafting onto TiO2 identified by formation of vibration band between Ti and triazine. SEM mapping shows that C, O, Ti, and N are homogeneously distributed in the nanomaterial. Nitrogen adsorption-desorption measurements at 77 K show developed textural properties; the heat of N2 adsorption seems to be affected by CA loading. PL and UV-visible spectroscopies show simultaneously (i) electron trapping by the oxygen vacancy identified by Raman spectroscopy by redshift of Eg1 mode and (ii) the hole is confined by nitrogen. Therefore, the excited electron can move from TiO2 VB to the new sublevels initiated by the introduction of nitrogen which results in quenching of the photoluminescence intensity. The photocatalytic activity of the various TNCAs nanomaterials increases versus CA loading. The highest kLH of TNCA2 (5 wt%) could be explained by short migration time conjugated with lower bulk recombination of the photogenerated electron hole. Keywords: Photocatalysis, Cyanuric acid, Nanohybrids, Formic acid, Kinetics

The photocatalytic degradation of environmentally non-benign, toxic organic pollutants such as bisphenol A (BPA), brilliant green (BG), or mixture of dyes have been carried out using g-C3N4-TiO2 (GNT) nanocomposites. The GNT nanocomposites were synthesized by using hydrothermal method with different compositions and these nanocomposites were characterized using the different techniques. X-ray diffraction revealed that the anatase phase of TiO2 has been retained in composites; while characteristic reflection of g-C3N4 at 27.07° (d = 3.22 Å) is not observed due to its lower content in the nanocomposites. Raman spectra confirms the formation of composites between TiO2 with g-C3N4. Furthermore nano-scale dimensions of the bare or composites have been proved by FE-SEM and HR-TEM analysis. X-ray photoelectron spectroscopy (XPS) shows the presence of C, N, Ti and O as a constituents, with peaks due to CC, NCN of g-C3N4. Among the different nanocomposites, g-C3N4-TiO2 catalyst having 30% g-C3N4 and 70% TiO2 in molar proportion (i.e. 30-GNT) is exhibiting the highest efficiency for degradation of the different dyes in correlation to its higher surface area, lower optical band gap as well as more visible-light absorption (i.e., λ > 400 nm) in the electromagnetic spectrum. Keywords: Nanocomposites, TiO2, g-C3N4, Photocatalytic degradation, Bisphenol A, Brilliant green

In the present paper, a one-step, simple, efficient and low-cost strategy was demonstrated for preparing of highly stable hybrid platinum-titania (Pt@TiO2) photocatalyst by solvothermal wet chemical process. Platinum (Pt) in the metallic form combined with titania (TiO2) in the crystallographic anatase form has been manufactured using Dimethyl Sulfoxide (DMSO) as a solvent and surfactant using titanium (IV) butoxide and hydrogen hexachloroplatinate(IV) precursors. Full characterization of the hybrid nanomaterials including their morphology, crystalline structure and optical properties was determinate using different experimental techniques such as XRD, TEM and UV–vis spectroscopy. TEM images showed spherically shaped Pt nanoparticles (NPs) of the diameter 5–10 nm with good particle size distribution. The EDXRF data revealed that Pt NPs are in metallic form. Optical investigation show that Pt@TiO2 NPs exhibits a good optical response under UV–vis light excitation compared to bare-TiO2. Furthermore, photocatalytic investigation of Pt@TiO2 colloids photocatalyst towards the photodegradation of diuron, as a model organic pesticide was reported. The hybrid Pt@TiO2 photocatalyst prove high-performance on the photodecomposition of the pesticide under solar light within only 60 min. In the other hand, the plasmonic hybrid Pt@TiO2 was incorporated into the cotton fabric to attain a modified fiber with high self-cleaning activity. Keywords: Solvothermal method, Nanocomposites, Semiconductors, Heterogenous catalysis, Cotton fiber, Self-cleaning

Three-dimensional (3D) TiO2 hollow structures have attracted much attention due to their unique properties. However, the large bandgap of (3.2 eV) results in the fact that anatase TiO2 photocatalyst can only be excited by UV light, which only accounts for 3–5% of the solar energy. On considering that nobel metallatic nanomaterials can harvest visible light due to surface plasmon resonance (SPR) effect, in this paper, three kinds of Au nanoparticles with different morphologies, namely Au nanospheres (Au-NSs), Au nanorods (Au-NRs) and Au nanopentogons (Au-NPs) were prepared and used as photosensitizers to modified TiO2 hollow nanoboxes (TiO2-HNBs), aiming to explore high efficient visible-light-responsive photocatalyst. The photoreacitivty of Au/TiO2-HNBs was evaluated by photoctalytic oxidation of Rhodamine B (RhB) and NO under visible irradiation (λ > 420 nm). It was found that the visible photoreactivity of TiO2-HNBs was greatly enhanced after modified with Au nanoparticles, and TiO2-HNBs loaded with Au-NRs exhibit the highest visible photocatalytic activity towards both RhB degradation and NO oxidation. Upon visible irradiation, SPR effect induces the production of hot electrons from the Au nanoparticles, which can further transfer to the conduction band of TiO2-HNBs to produce superoxide radicals (·O2−), resulting in an efficient separation of photo-generated electron-hole pairs. The photoreactivity of Au-NRs/TiO2-HNBs towards RhB degradation almost keeps unchanged even after recycling used for 5 times, indicating that it is promising to be use in practical applications. Keywords: Au, TiO2, Hollow nanobox, Surface plasmon resonance, Photocatalysis

TiO2-supported clinoptilolites (TiO2/clinoptilolites) were successfully synthesized with controlled crystal phase and particle size via hydrothermal method to enhance photocatalytic performance of TiO2. The effects of various parameters including temperature, acidity and concentration of Ti-containing solutions on the particle size, crystal phase and agglomeration of TiO2 supported on clinoptilolite were investigated thoroughly by characterizations of X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscope (SEM), transmission electron microscope (TEM), BET isotherm, UV–visible (UV–vis) spectrophotometer and Malvern zetasizer. The results demonstrate that increasing temperature and strengthen acidity are beneficial to enhance the crystallinity and particle size of supported TiO2. Increase in acidity also leads to more uniform distribution of TiO2 on the surface of clinoptilolite. The TiO2 nano-crystals deposited on the surface of clinoptilolite, exhibit rutile or anatase phase, strongly depending on the preparation procedure. The resultant TiO2/clinoptilolites could be used as photo-catalysts for the degradation of crystal violet (CV) dye in aqueous solution, showing a higher photo-catalytic activity with 89% degradation within 100 min. The effect of operational parameters, such as pH values of reaction media, dose of used catalyst, and concentration of CV dye on the CV degradation performance were investigated, in which the kinetics of CV dye degradation was found to follow the pseudo-first order kinetic model. Keywords: TiO2, Clinoptilolite, Hydrothermal method, Crystal phase, Degradation, Crystal violet dye

The effect of 5 MeV Cu++ ions irradiation on structural and optical properties of Anatase TiO2 nanoparticles (TiO2-NPs) is investigated. For this purpose, TiO2-NPs are irradiated with different Cu++ ions fluences, ranging from 1 × 1015 to 1 × 1016 ions/cm2 at room temperature. XRD results confirm the Ti3O7 phase appear at the dose of 5 × 1015 ions/cm2 and peak intensity of Ti3O7 phase gradually increases with an increase of Cu++ ions irradiation dose. At the dose of 1 × 1016 ions/cm2 TiO2 Anatase phase were transformed to Rutile phase. Same observations are confirmed from Raman spectroscopy. High resolution transmission electron microscopy (HRTEM) reveals that morphology converted into wavy shape and crystal structure detrioted with increase Cu ion irradiation dose to form vacancy loops and interstitial loops. Scanning electron microscopy (SEM) shows that TiO2-NPs have been fused to form a cluster of nanoparticles at high Cu ion beam dose, while bandgap of TiO2-NPs reduces from 3.19 eV to 2.96 eV as a function of Cu++ irradiation fluence. These phase transformations and crystal damage are the responsible for optical bandgap reduction. The mechanism for the currently observed phase transformation of TiO2 and coalescence of TiO2-NPs are discussed in term of thermal spikes model. Keywords: TiO2 nanoparticles, Cu++ irradiation, Rutile phase, Coalescence of NPs, Bandgap engineering

A facile and green synthetic approach was considered for the synthesis of stabilized titanium dioxide (TiO2) nanoparticles. Extracts of Alcea and Thyme plants were used to synthesis TiO2 nanoparticles for photocatalytic applications. Evaluation of the structural and phase formation via X-ray diffraction (XRD) indicated the formation of the anatase phase of TiO2 along with the rutile phase. A desired single phase of anatase was obtained upon heating the as-synthesized samples at 500 °C for 3 h. Using the information provided by the XRD analyzer and the Debye Scherer relationship, the average crystallite size was found to be around 6 and 10 nm for the samples synthesized using Alcea and Thyme plants, respectively. To determine the elemental analysis and chemical structure, the energy dispersive X-ray (EDX) analyzer and Fourier Transform Infrared (FTIR) spectroscopy were employed. Field emission scanning electron microscopy (FESEM) indicated batches of ultrafine agglomerated particles for both samples, which their sizes grew by the heating process. The UV–visible analysis of photocatalytic properties confirmed the priority of TiO2 nanoparticles prepared with Thyme extracts. Keywords: TiO2nanoparticles, Green synthesis, Photocatalytic properties

This study synthesized TiO2 nanoparticles using the sol-gel method assisted by heat from Titanium (IV) Isopropoxide. Samples were calcined at 400, 600, and 800 °C, and studied for self-cleaning application. The nanoparticles were characterized using X-ray diffraction (XRD), Scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, and UV-vis spectroscopy. A self-cleaning application test was also performed using methylene blue dye as a form of contaminant. The TiO2 nanoparticles showed improved crystallinity with increased calcination temperature and experienced a phase transformation from anatase to rutile after 800 °C calcination. Crystallite size ranged from 5.11 to 24.97 nm for anatase and 15.85 to 24.72 nm for the rutile from the XRD result. Raman spectra showed increased peak intensities with an increase in calcination temperature. The grain size distribution from TEM analysis revealed the particle size with the uniform count at 400 °C and 800 °C than at 600 °C. The bandgap for direct transition was evaluated to be 3.07 eV. The self-cleaning test confirmed that the TiO2 nanoparticles would be effective in self-cleaning applications. The sample that was calcined at 600 °C displayed the highest self-cleaning ability.

In this research work, the linear and nonlinear optical properties of linear low-density polyethylene (LLDPE) composites with anatase phase of titanium dioxide nanoparticles in different weight percentages are investigated. Solvent casting method have been used to synthesize the thin film of LLDPE/anatase nanocomposites. Thin films are characterized via XRD technique and field emission scanning electron microscope (FESEM). Wrinkles formed on the surface of thin films by adding the titanium dioxide. Linear optical and electrical parameters such as linear absorption coefficient, extinction coefficient, refractive indices, optical conductivity, and dielectric constants at various wavelengths from 190 nm-2700 nm are determined for different weight percentages of nanoparticles in polymer nanocomposites. Z-scan technique has been employed to explore the nonlinear optical properties using CW laser at 532 nm wavelength. The nonlinearity is examined at various irradiance of laser to study the effect of irradiance on nonlinear optical properties. Pure LLDPE has saturable absorption (SA) at low laser irradiance. As the laser irradiance increases, the nonlinearity behavior turns from SA to reverse saturable absorption (RSA). The results show the suitability of the thin films for the applications in optical devices that involve the use of optical limiting properties of materials.

The novel mesoporous TiO2/BMMs nanocomposites using bimodal mesoporous silica (BMMs) as support and rutile-anatase mixed phase as active species were successfully synthesized via hydrothermal and subsequent calcination method. Their structural and physiochemical properties were characterized by X-ray diffraction, scanning/transmission electron microscopy, BET-isotherms, inductive coupled plasma optical emission spectroscopy, zeta potential, Fourier transform infrared and UV-visible spectroscopy. The results demonstrated that the photocatalytic degradation activity of the synthesized catalysts were extensively enhanced as compare to bare TiO2, due to the highly uniform dispersion of mixed phases (Anatase and Rutile) TiO2 on the bimodal mesoporous surfaces. Particularly, the catalytic efficiency became increased as increasing the calcination temperature, showing the highest (98%) overall removal of CV dye using ATB5d as catalyst calcinated at 800 oC. Its most interesting finding is that the % adsorption of TBH5d was 46 %, more than that (26%) of TBH5c calcinated at 600 ℃, however, its % degradation was 21 %, lower than that (39 %) of TBH5c for dye concentration of 20 ppm in 50 min. Meanwhile, the kinetic adsorption and degradation performances were followed the pseudo second and first order models, respectively, further proving the high degradation efficiency of ATB5c with high rate constant than that of ATB5d. Thermodynamic parameters (ΔGads, ΔHads, and ΔSads) were calculated, suggesting the spontaneous and exothermic procedure with high entropy, while the adsorption equilibrium data was fitted to Dubinin-Radushkevich model. Both TBH5c and TBH5d showed an excellent stability and reactivity 71.2 and 61 %, respectively, even after 5th cycles. Thus, these results suggested that that TBH5c may be one of the suitable candidates in wastewater treatments.

3D ordered superstructures of mesocrystalline NH4TiOF3 and (NH4)2TiOF4 are synthesized via in-situ evolution from anodic TiO2 nanotube arrays grown on the Ti metal substrate under high current density. As revealed by X-ray diffraction, scanning electron microscopy and transmission electron microscopy characterizations, the obtained NH4TiOF3 and (NH4)2TiOF4 mesocrystals consist of well aligned nanoparticle subunits at atomic level and can be converted to TiO2 (anatase) mesocrystals with their original exterior shapes retained upon thermal annealing. Close examination suggests that NH4TiOF3 and (NH4)2TiOF4 mesocrystals form via a nonclassical crystal growth process involving fast oriented aggregation of particles assisted by electric field-dipole interaction.

Recently, interest has been directed towards the grafting of metal oxides with organophosphonic acids bearing terminal amine groups to extend the functionality and applicability of these materials. Previous reports mainly focus on the application perspective, while a detailed characterization of the surface properties at the molecular level and the correlation with the synthesis conditions are missing. In this work, mesoporous TiO2 powder is grafted with 3-aminopropylphosphonic acid (3APPA) under different concentrations (20, 75, 150 mM) and temperatures (50, 90 °C) and compared with propylphosphonic acid (3PPA) grafting to unambiguously reveal the impact of the amine group on the surface properties. A combination of complementary spectroscopic techniques and Density Functional Theory-Periodic Boundary Conditions (DFT/PBC) calculations are used. At 90 °C and high concentrations, lower modification degrees are obtained for 3APPA compared to 3PPA, due to amine-induced surface interactions. Both X-ray Photoelectron Spectroscopy (XPS) and Diffuse Reflectance Infrared Fourier Transform (DRIFT) spectroscopy reveal that both NH2 and NH3+ groups are present, with also contributions of NH2 groups involved in hydrogen bonding interactions. A similar ratio of NH2/NH3+ (65:35) is obtained irrespective of the modification conditions, suggesting similar relative contributions of different surface conformations. Calculated adsorption energies from DFT calculations on 3APPA adsorption on anatase (1 0 1) in relation to the water coverage reveals a coexistence of various structures with the amine group involved in intra-adsorbate, inter-adsorbate and adsorbate–surface interactions. Further validation is obtained from the strong overlap of different 31P environments represented by the broad band (35-12 ppm) in experimental 31P Nuclear Magnetic Resonance (NMR) spectra and calculated 31P chemical shifts of all modelled monodentate and bidentate structures. Structures related to the tridentate binding mode are not formed due to geometric restrictions of the anatase (1 0 1) facet applied as model support in the calculations. Nevertheless, they could be present in the experimental samples as they are composed of anatase (representing multiple crystal facets) and an amorphous titania fraction.

We report on the preparation and optimization of low temperature (

This paper demonstrates the fabrication of highly ordered mesoporous titanium dioxide (OMT) with different transition metals (TM: Fe, Mn, and Ni) by employing a self-assembly surfactant template route. The ordered TM-loaded mesoporous TiO2 (TM-OMT) has uniform mesopores (3–5 nm pore diameter), and a crystalline framework is successfully prepared via soft template strategy by employing Pluronic® F127 triblock copolymer as a chelating and structural directing agent. The structural and optical characteristics of the TM-OMT hybrids have been examined by scanning electron microscopy (SEM), transmission electron microscope (TEM), XRD, N2-sorption isotherms, UV/visible diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy (XPS) reveals the successful incorporation of TM ions over the highly ordered mesostructured OMT. The XRD pattern evidenced that the obtained TM-doped OMT samples are pure anatase of the crystalline phase. By employing TEM analysis, the average particle size is estimated to be 2–2.7 nm, whereas diffraction patterns have evidenced the polycrystalline features of the mesoporous structure. The bandgap energy of TM-doped mesoporous decreases according to the particular metal and its amount due to the reduced particle size. This cost-effective method provides the exceptional potential to tune the optical features for TM-doped mesoporous TiO2 materials for its optoelectronic applications and show more significant promise for energy conversion technologies.

Photocatalytic activity of titania–based photocatalysts doped with 1% La has been tested in UVA radiation-induced degradation of two β-blockers – metoprolol tartrate (MET) and propranolol hydrochloride (PRO). Photocatalysts have been synthesized by sol–gel process followed by calcination at various temperatures in the range of 450–750 °C. The great impact of calcination temperature on the structural, compositional and morphological properties of prepared catalysts has been revealed by XRPD, SEM, BET and Raman scattering measurements. Doped catalysts calcined at 450–650 °C, with dominant anatase phase and developed mesoporous structure, have displayed higher photocatalytic performance than much less porous samples calcined at 700–750 °C, with sodium hexatitanate as dominant phase. Also, La-doped anatase sample has shown higher efficiency in degradation of MET and PRO in comparison with the efficiency of undoped TiO2 nanopowders calcined at same temperatures. The quenching effects of various scavengers suggest that the major role in degradation of MET may be attributed to reactive radicals, whereas photogenerated holes are mainly responsible for degradation of PRO. Applying density functional theory (DFT) calculations, we analyzed fundamental structural and electronic properties (total and polar surface areas, frontier molecular orbitals, optoelectronic properties and average local ionization energy surfaces) of MET and PRO molecules, which are of significance for the understanding of more effective degradation of PRO in comparison with MET. Keywords: β-blocker, Photocatalysis, Anatase, La-doping, Density functional theory (DFT), Average local ionization energy (ALIE)

Brookite TiO2 nanoparticles were synthesized by hydrothermal method and characterized by X-ray powder diffraction (XRD), diffuse reflectance UV–Visible spectroscopy (DRUV), and scanning electron microscopy (SEM). The obtained particles were spherical in shape with the diameter of about ~10 nm under the hydrothermal temperature of 175 °C. The photocatalytic performance of brookite was investigated in the photodegradation of dyes (rhodamine B and rose bengal) under UV-A radiation by low-power lamp. The activity of brookite and the photodegradation efficiency of dyes were estimated using a UV–Visible spectrophotometer and a total organic carbon (TOC) analyzer. Compared to anatase and rutile prepared by the similar synthesis procedure, brookite is highly active in terms of decolourization, aromatic ring opening, and mineralization. Keywords: Brookite, Anatase, Dye, Photocatalytic degradation, Decolourization, Mineralization

The effects of phase changes on the photocatalytic and catalytic activities of SnO2/TiO2 nanoparticles prepared via a surfactant-assisted sol-gel method were investigated. The as-prepared SnO2/TiO2 was calcined at 400°, 500°, 600°, and 700 °C. The prepared samples were studied by XRD, TEM, SEM, FTIR, BET, UV-vis diffuse reflection spectroscopy (DRS) and Photoluminescence (PL) spectra. The results showed that the crystallite size and anatase-to-rutile phase transformation increased greatly with increasing the calcination temperature. The transformation of anatase to rutile phase was found to be between 400° and 600 °C, and then the anatase completely transformed to rutile phase at 700 °C. Also, the specific surface area and pore volume decreased, whereas the mean pore size increased with increasing the calcination temperature. The effect of calcination temperature on the catalytic activity of the samples was tested by different applications: photodegradation of Methylene Blue (MB), Rhodamine B (RhB) dyes and phenol and synthesis of xanthene (14-phenyl-14H-dibenzo [a,j]xanthene). The mineralization of MB and RhB has been confirmed by chemical oxygen demand (COD) measurements. The SnO2/TiO2 nanoparticles calcined at 500 °C are found to exhibit the highest photocatalytic and catalytic activities. Keywords: SnO2/TiO2 nanoparticle, Calcination temperature, Photodegradation, Xanthene, Methylene blue, Rhodamine B, Phenol