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Titanium dioxide is one of the earliest materials used in memristors. It is widely studied and researched due to its advantages of the simple preparation process, high dielectric constant, wide bandgap and chemical stability. In this paper, a two-step anodization process was used to prepare the oxidized nanotubes array, which served as the foundation for fabricating Ag/TiO₂/Ti memristors. The research delved into the impact of diverse oxidation voltages on the resistive performance of memristor and discussed the underlying mechanism for resultant performance.

Nowadays, the attention of researchers about titanium dioxide (TiO${}_2)$ nanomaterials has increased due to their bactericidal, nontoxic, safe, cost-effective, stable, noncarcinogenic and industrial applications. This study aims to fabricate the electrospun branched PVDF/TiO₂ nanofiber webs with tiny diameters and evaluate their performance in food fresh-keeping. The surface morphology, infrared spectroscopy, antibacterial properties and air permeability of the electrospun nanofiber web have been tested. Our results showed that the branched PVDF/TiO₂ nanofibers with a diameter of less than 4nm can be electrospun smoothly. Furthermore, these webs have exhibited great potential in preserving the core of bananas fresh owing to their antibacterial properties, nonpoisonous, edible, edible and breathability.

Several zinc(II) and aluminum(III) phthalocyanines substituted by carboxylic acid and sulfonic acid groups were anchored to nanocrystalline TiO₂ films. By irradiation with visible light the photovoltaic behavior of the electrodes containing LiI/LiI₃/propylene carbonate electrolyte was measured. Most efficient results were found using zinc(II) 2,9,16,23-tetracarboxyphthalocyanine, with a current conversion efficiency at 700 nm approaching 45%. It is shown that electron injection into TiO₂ occurs from the excited singlet state of the phthalocyanine derivatives. High stability of the cell performance under continuous irradiation was found.

Adsorption of phthalocyanines lacking conventional attaching substituents onto nanostructured TiO₂ electrodes has been studied, and some of the important factors for sensitisation have been identified. Tetra-dimethoxyphenyl phthalocyanine (2) and tetra-phenyl phthalocyanine (3), derived from 4-(2,5-dimethoxyphenyl)phthalonitrile and 4-phenylphthalonitrile, respectively, are shown to successfully sensitise nanostructured TiO₂ electrodes, with IPCE_max of 9 and 5% at λ = 650 nm. The dye-oxide systems have been characterised by UV-vis spectroscopy, cyclic voltammetry and photoelectrochemical methods, and the dye–surface interactions are discussed.

The sol–gel method was used to prepare amorphous TiO₂ powders with sub-micrometric grain size. These powders together with commercial nanometric TiO₂ were characterized with FT-IR spectroscopy, X-ray diffraction, scanning electron microscopy, and a light scattering method. Then electrorheological suspensions were composed out of these powders and their flow curves under electric field were recorded. The ER activity of the synthesized powders was relatively high which probably resulted from residual amounts of polar organic matter present in the prepared titania. It was found, however, that the studied suspensions underwent a very well pronounced agglomeration process clearly observed in suspensions of higher concentrations and particularly in those fluids which were exposed to electric field for some time. Therefore, the studied ERFs which were originally prepared out of nanometric powders contain in fact aggregated particles of considerably bigger size. The agglomeration process strongly influences all basic properties of the studied electrorheological suspensions.

In this study, titanium dioxide nano powders were electrophoretically deposited on the stainless steel in Isopropanol and Triethanolamine as a solvent and dispersant, respectively. The effects of deposition parameters including deposition voltage (5 to 20 V) and deposition time (5 to 60 s) on the microstructure and surface topography were examined by scanning electron microscope (SEM) and scanning probe microscope (SPM), respectively. In addition, the effects of these deposition parameters on packing density were investigated. This research revealed that substrate surface is fully covered with increasing deposition voltage and deposition time. Therefore packing density of deposited films is strongly dependent on the deposition parameters and reached its highest value at 20 V and 60 s. In addition, results show that surface roughness is increased by increasing the deposition voltage and deposition time.

Rational design of hybrid biomolecule — nanoparticulate semiconductor conjugates enables coupling of functionality of biomolecules with the capability of semiconductors for solar energy capture, that can have potential application in energy conversion, sensing and catalysis. The particular challenge is to obtain efficient charge separation analogous to the natural photosynthesis process. The synthesis of axially anisotropic TiO₂ nano-objects such as tubes, rods and bricks, as well as spherical and faceted nanoparticles has been developed in our laboratory. Depending on their size and shape, these nanostructures exhibit different domains of crystallinity, surface areas and aspect ratios. Moreover, in order to accommodate for high curvature in nanoscale regime, the surfaces of TiO₂ nano-objects reconstructs resulting in changes in the coordination of surface Ti atoms from octahedral (D_2d) to square pyramidal structures (C_4v). The formation of these coordinatively unsaturated Ti atoms, thus depends strongly on the size and shape of nanocrystallites and affects trapping and reactivity of photogenerated charges. We have exploited these coordinatively unsaturated Ti atoms to coupe electron-donating (such as dopamine) and electron-accepting (pyrroloquinoline quinone) conductive linkers that allow wiring of biomolecules and proteins resulting in enhanced charge separation which increases the yield of ensuing chemical transformations.

Titanium dioxide has been in close examination for application development due to its high index of refraction and transparency across the visible range. One of the most active researches is hydrophilicity and photocatalysis in TiO₂ films. In this study, a close investigation to TiO₂ films' microstructural transformation was examined. A number of thin film samples were prepared by ion-assisted electron-beam evaporation at 200-nm nominal thickness, 2.0 Å/s deposition rate and 250°C deposition temperature. The varying parameter was the oxygen flow rate at 2, 4, 6 and 8 sccm. The films were eventually annealed for three hours in air atmosphere. The crystalline structures of as-deposited (ASD) and annealed films were deduced by variable-angle spectroscopic ellipsometry (VASE), and supported by X-ray diffractometry (XRD) and atomic force microscopy (AFM). Film characterization based on VASE is desirable in order to understand physical and optical characteristics of the films. Transmittance spectra were derived from UV/Vis spectrophotometer. It was found that all as-deposited films were all amorphous with low luminous transmittance. Higher oxygen flow rate during the deposition, however, resulted in sub-oxide TiO₂ film. With this film, annealing at 300 and 500°C were presumed as transition temperatures for amorphous-to-anatase and anatase-to-rutile phases, respectively. The luminous transmittance also increased and was found to be the highest at 75.75% at 400°C annealing. The optical energy band gap for this film also increased up to 3.26 eV at 600°C annealing.

Introducing different atoms into TiO₂ crystal lattice is a famous method to improve photocatalytic activity of TiO₂ under visible-light irradiation. In this paper, Nitrogen (N) and fluorine (F)co-doped TiO₂ powders were prepared by mixing TiCl₃ solutions with ammonium fluoride (NH₄F). In preparation, we used NH₃-H₂O solution for adjustment of pH values (pH 2, 7, and 9) of mixed solution. X-ray diffraction (XRD) indicated N,F-TiO₂ powders prepared at pH7 and pH9 contained only anatase phase, but the powders prepared at pH2 contained both anatase and rutile phase. The result of XRD also indicated N,F-TiO₂ powders prepared at pH7 had the smallest crystallite size. We measured photocatalytic activity of prepared N,F-TiO₂ powders by the decomposition of methylene blue. N,F-TiO₂ powder prepared at pH7 and pH9 showed same high photocatalytic activity under ultraviolet light irradiation (peak wave length = 352 nm). Furthermore, under green light LED irradiation (wave length = 525 nm), a sample prepared at pH7 decomposed methylene blue more quickly than any other samples. As the result, N,F-TiO₂ prepared at pH7 had the best catalytic activity under both UV-light and visible light in the all of N,F-TiO₂ prepared and reference TiO₂ photocatalyst (ST-01 produced by Ishihara Co. Ltd).

Titanium dioxide (TiO₂) thin films are prepared on glass substrates by metal-organic chemical vapor deposition (MOCVD) method using the different organic solvents, e.g. ethanol or cyclohexane, in nitrogen carrier gas with different their concentrations. We reported the effects of the each organic solvent in the carrier gas for MOCVD method on the morphology of the composed particles, the thickness, the surface roughness, and the transparency of the prepared TiO₂ thin films with changing the deposition temperature. The morphology of the particles which compose the thin films, and the surface roughness of the prepared TiO₂ thin films are observed and measured by atomic force microscope (AFM) and field emission scanning electron microscopy (FE-SEM). The film thickness is measured by fluorescent X-ray spectroscopy (XRF), and the transparency of the films is confirmed by UV-vis spectroscopy. The transparencies of the TiO₂ thin films differ depending on the MOCVD conditions, e.g. the organic solvents species, the concentration of the container in the carrier gas and the deposition temperatures. We have found that the species and the concentration of the organic solvents in the carrier gas are very important factor to prepare homogeneous TiO₂ thin films by MOCVD method; cyclohexane inhibits to aggregate of the TiO₂ nanoparticles on the glass substrate during the MOCVD process.

Transition metal oxide photocatalysis is a relatively new method representing advanced oxidation process to be applied in industrial wastewater treatment especially for degradation of organic pollutants. We investigate TiO₂ as a photocatalyst for the photocatalytic degradation of Rhodamine B (RhB) under simulated sunlight. Various parameters and their effectiveness have been studied. The effects of processing parameters including catalyst loading and feed concentration were investigated; and the degradation pathway was proposed based on the UHPLC-MS analysis. The result showed that a higher kinetic rate can be obtained by employing low catalyst loading and feed concentration, i.e., 0.5 g/L of TiO₂ loading and 5 ppm of RhB concentration, respectively. For this particular system, the optimum degradation rate ($k$) can achieve 0.297/min. The effectiveness of solar light-TiO₂ system for RhB degradation shows this method can be used for wastewater treatment.

The difficulty of recycling and low photocatalytic efficiency in the visible light significantly limit the use of nano-TiO₂ in water pollution control. In this work, Bucky papers (BPs), which play a vital role for adsorption of pollutants and transfer of electrons, are introduced as substrates to fabricate and anchor TiO₂ nanorods by a facile hydrothermal method. The photocatalytic properties of the TiO₂ and BP composites (TiO₂@BP) are studied by photodegrading methylene blue in water solutions. It is found that TiO₂@BP possesses four times photocatalytic efficiency for methylene blue of TiO₂@Si under ultraviolet light irradiation and 10 times under visible light irradiation. This is considered to be attributed to the synergic effect of TiO₂@BP system and surface defects of TiO₂ nanorods. The TiO₂@BP also shows a stable photocatalytic property even after five cyclic photocatalytic degradation. This study indicates that TiO₂@BP is a promising candidate for photocatalytic applications, which provides a reference for further research on synthesis of reusable photocatalysts with higher efficiency.

In this study, we have studied the electronic structure and magnetic properties of oxygen vacancy on anatase TiO₂ (101) surface using density functional theory (DFT) calculations. The results show that only the vacancy of threefold-coordinated oxygen (O_3c) can introduce the magnetism on (101) surface. The spins induced by the O_3c vacancy will form a stable ferromagnetic state, and it can introduce a magnetic moment of 1.05 μ_B. Moreover, the magnetic moment mainly results from the d orbitals of three low-charge-state Ti ions adjacent to the O_3c vacancy. The O_3c vacancy on (101) surface can also result in a localized state of spin polarization in the bandgap, which is about 0.22 eV below the Fermi energy. Our findings imply that the oxygen vacancy on the surface may be responsible for the unexpected ferromagnetism in pristine TiO₂ film. The experimentally observed d⁰-ferromagnetism behavior in TiO₂ system is in good agreement with our calculated results.

In this work, we performed differential scanning calorimetry (DSC) experiments to investigate the phase transition temperature and the molar enthalpy of the absorbed water confined in porous titanium dioxide. The porous titanium dioxide with three different pore size distribution and different filling fraction of the absorbed water were examined. We found that both the pore size of the examined samples and the filling fraction of the absorbed water affected the water’s phase transition temperature and its molar enthalpy.

In this study, titanium dioxide was synthesized by using a hydrothermal technique at different growth temperatures. The study involved investigating the effects of growth temperature on crystal structure, surface area, morphology, and photocatalytic properties. The results indicated the growth of pure monoclinic titania. Additionally, an increase in growth temperature led to the formation of nanostructures to form nanowires and nanorods from nanospheres. The findings revealed variations in crystal quality at different growth temperatures. All samples displayed monoclinic crystal structure with the same molarity at different temperatures including 140${}^{\circ }$C, 160${}^{\circ }$C, and 180${}^{\circ }$C. Various parameters were optimized to grow nanowires and nanorods with a monoclinic crystal structure. The planes of the grown nanostructures were same across all the samples. The grown nanostructures were applied in the degradation of a crystal violet (CV) dye that is also used in optical applications. The study involved demonstrating the excellent photodegradation properties of CV by using a synthesized nanophotocatalyst and providing a detailed discussion on the effects of morphology and crystal structure with respect to photocatalytic properties. The findings also revealed the improved photocatalytic results with respect to nanostructures due to the presence of a broad light harvesting region and the lifetime of the photogenerated electron–hole pair.

The doctor blade coating method is used to prepare dye-sensitized solar cells (DSSCs) and dope the original titanium dioxide (TiO₂, P25) photoanode (PA) with single-layer graphene (G), graphene quantum dots (GQDs), and gold (Au) nanoparticles in this research. The results show that doping PAs with G, GQDS, and Au effectively increases the short-circuit current density ($J_{\mathrm{\text{sc}}})$, conversion efficiency ($\eta$), and decreases the internal structure impedance ($R_k$) of DSSCs. $J_{\mathrm{\text{sc}}}$ increases from 13.62 to 17.02, 15.22, 16.05 mA/cm², while $\eta$ (%) increases from 6.36 to 7.50, 7.08, 7.04% when doping G, GQDs, and Au, respectively. The analysis of Electrochemical Impedance Spectroscopy (EIS) reveals that the doping decreases $R_k$ from 11.28 to 8.36, 8.78, 8.54 $\mathrm{\Omega }$, respectively. Then, the titanium dioxide (TiO${}_2)$-doped G-GQDs, G-Au, and QDs-Au on DSSCs influence $J_{\mathrm{\text{sc}}}$ that increases to 5.45, 15.37, and 15.31 mA/cm², respectively. In this case, the values of $\eta$ are found to be 7.21%, 7.35%, and 7.00%, while those of $R_k$ are 8.44, 8.63, and 9.18 $\mathrm{\Omega }$. The values of $J_{\mathrm{\text{sc}}}$ and $\eta$ are highest but that of $R_k$ are lowest when doping with G, which proves that the photoanode of the DSSC effectively activates the photogenerated electrons in the film by doping single-layer graphene and TiO₂ captures its electrons through graphene. The decreasing electron–hole recombination rate allows the photogenerated electrons to be quickly transferred to the external circuit. As a result, the efficiency of DSSCs is improved.

In this theoretical study, a path was adapted to investigate the redshifting of the TiO₂ absorption edge by molybdenum (Mo), yttrium (Y) and nitrogen (N) doping. The geometrical model, band gap and photo response were noted in the developed model of anatase TiO₂. The tri-doped model showed very small modification in the structure as compared to a reference TiO₂ model. The 3d states of Mo mix up with the 3d states of Ti, resulting in the reduction of band gap. The Y 2p states were introduced around the middle of the band gap of Y-doped TiO₂. Good reduction was found in the gap of tri-doped TiO₂ model and the created states were occupied. The doping of N via oxygen (O) substitution in tri-doped model resulted in the band gap reduction by introducing states in the band gap due to the mixing of N 2p and O 2p states.

In this work, nanocrystalline TiO₂/ITO electrodes were prepared by sol–gel method starting from tetrabutyl orthotitanate (Ti(OBuⁿ)₄) reacted with hydrogen peroxide in the ice-water bath. The sol–gel derived TiO₂ films were characterized by XRD, SEM, BET, and UV/Vis absorption spectroscopic techniques. The preparation conditions, including the number of coats and calcination temperature, were also investigated. Furthermore, PEC cells were constructed for testing the activities of prepared TiO₂/ITO photoelectrodes. The photo-currents for hydrogen production via the PEC reaction were measured under UV irradiation (λ_max = 253.7 nm). The experimental results showed that the sol–gel derived TiO₂ films calcined at 300°C–600°C were anatase structure and they showed a maximum UV/Vis absorption at about 380 nm. Moreover, from the result of PEC reactions, it was found that the TiO₂/ITO photoelectrode (calcined at 600°C, with the thickness of TiO₂ layer of about ~0.2 μm) demonstrated a large saturation current (0.326 mA/cm²) with a quite high photoelectrochemical conversion efficiency of 2.39%.

Activated carbon fibers supported TiO₂ photocatalyst (TiO₂/ACF) in felt-form was successfully prepared with a dip-coating process using organic silicon modified acrylate copolymer as a binder followed by calcination at 500°C in a stream of Ar gas. The photocatalyst was characterized by SEM, XRD, XPS, FTIR, and BET surface area. Most of carbon fibers were coated with uniformly distributed TiO₂ clusters of nearly 100 nm. The loaded TiO₂ layer was particulate for the organic binder in the compact film was carbonized. According to XPS and FTIR analysis, amorphous silica in carbon grains was synthesized after carbonizing organic silicon groups, and the Ti–O–Si bond was formed between the interface of loaded TiO₂ and silica. Additionally, the space between adjacent carbon fibers still remained unfilled after TiO₂ coating, into which both UV light and polluted solutions could penetrate to form a three-dimensional environment for photocatalytic reactions. While loaded TiO₂ amount increased to 456 mg TiO₂/1 g ACF, the TiO₂/ACF catalyst showed its highest photocatalytic activity, and this activity only dropped about 10% after 12 successive runs, exhibiting its high fixing stability of coated TiO₂.

Titanium dioxide pigment is a white pigment of high performance. However, its production could cause severe environmental and resource problems. In this paper, powder quartz/TiO₂ composite particles (PQ/TCP), a type of core (powder quartz)–shell(TiO₂) composite powder, were prepared by a mechano-chemical method. The pigment properties of PQ/TCP and the mechanism of the mechano-chemical reaction between quartz and TiO₂ were investigated. Orthogonal analyses of experimental vairables showed optimal pigment characteristics of PQ/TCP under the following conditions: 4 h of activation for powder quartz, mixing/grinding at 1000 rpm for 1 h, with a mixing slurry made of 50% powder quartz and 0.4% dispersant. Powder quartz was evenly coated by TiO₂ and the Si–O–Ti bond was formed between powder quartz and TiO₂ in PQ/TCP as revealed by FTIR analyses and confirmed by surface thermodynamic calculation.