Particle Size Of TiO2 Research Articles

Enhanced optical and photo catalytic properties of V and La co doped TiO2 nanoparticles

To enhance the visible photo-catalytic activity of TiO2, La/V co-doped TiO2 materials were synthesized through a nonaqueous method of which the purpose was to reduce the aggregation between TiO2 particles. Different samples of La and V co-doped TiO2 nanoparticles were prepared through simple sol–gel synthesis method by using Vanadium(III) chloride as V precursor, Lanthanum(III) chloride heptahydrate as La precursor, and titanium (IV) butoxide (TBT) as titanium precursor. The effects of co-doping content on the structural, optical, and photo-catalytic properties of nanoparticles have been studied by X-ray diffraction (XRD), TEM, SEM and UV–Vis absorption spectroscopy. XRD results suggest that adding impurities has a great effect on the crystallinity and particle size of TiO2. Titania rutile phase formation in ternary system (Ti–La–V) was inhibited by La3+ and promoted by V4+ co-doped TiO2 in high concentration of vanadium and 22.6 mol% anatase composition is retained at 15% vanadium. The photocatalyst activity was evaluated by photocatalytic degradation kinetics of aqueous methylen orange under visible radiation. The results show that the photocatalytic activity of the 10 mol% V and 5 mol% La co-doped TiO2 nanopowders has a larger degradation efficiency than pure TiO2 under visible light.

Photocatalytic Degradation of Methylene Blue by Plasmonic Metal-TiO₂ Nanocatalysts Under Visible Light Irradiation.

This study demonstrates photocatalytic activity of 1 wt% plasmonic metal (Au, Ag and Cu)–TiO₂ nanocatalysts prepared via photodeposition method for the photo oxidative decomposition of methylene blue (MB 0.01 mM) under visible light (50 mWcm−2) irradiation. Plasmonic metal loaded-TiO₂ photocatalysts absorb with an absorption maximum at localized surface plasmon resonance wavelengths (500–785 nm). It has been observed that pH altered the surface charge (ζ) of TiO₂ (ζ = –4.98, –4.0 and +9.16 at pH = 10, 7 and 3, respectively). The point of zero charge (PZC) at pH 6.3 has been determined from a correlation plot between pH and ζ. Higher rate of degradation was observed at pH = 10 because of electrostatic interaction of cationic MB with anionic TiO₂. Higher photocatalytic activity was shown by Cu–TiO₂ followed by Au–TiO₂ and Ag–TiO₂ photocatalysts in comparison to TiO₂-P25. This enhancement in photocatalytic efficiency is attributed to the plasmonic effect and effective charge separation at the interface between nano size metal deposits and TiO₂ particles. The overall photocatalytic reaction followed pseudo first order kinetics as per Langmuir Hinshelwood kinetic equation. GC and GC-MS studies suggested the formation of thionin after demethylation and derivatives of benzene sulphonic acid which are subsequently degraded to CO₂ after prolonged irradiation time.

TiO2 Nanoparticles Synthesized with Ti(SO4)2 as Precursor via the Hydrothermal Method and their Optical Absorption Properties

Anatase TiO2 particles of about 20 nm in the diameter were successfully synthesized with Ti (SO4)2 as titanium source and stronger ammonia water as precipitant at 240°C for 48 h with pH=5 using the hydrothermal method. The samples were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and ultraviolet-visible absorption spectroscopy (UV-VIS). XRD analysis showed that the phase of the samples was anatase TiO2. TEM analysis confirmed that TiO2 particles of about 50 nm in the diameter were obtained when the pH value was 0.12. With the increasement of the pH value, the size of as-prepared TiO2 particles became remarkably fine. However, with the further increase of the pH value, the size of TiO2 particles was not obvious. TiO2 particles of about 20 nm in the diameter were obtained when the pH value was 5. And UV-VIS results showed that the size of anatase TiO2 nanoparticles, which became small, was propitious to the blue shift of their absorption peak.

The Effects of TiO2 Particle Size on the Properties of PTFE/TiO2 Composites

TiO2 filled polytetrafluoroethylene (PTFE) composite were fabricated for microwave circuit applications. PTFE/TiO2 composites were prepared by cold pressing and hot treating. The particle size of TiO2 varied from 5 μm to 11 μm.TiO2 powders with different sizes were prepared by the solid state ceramic route. The effects of TiO2 particle size on the microstructure, density, moisture absorption, thermal conductivity and microwave dielectric properties of PTFE/TiO2 composites were investigated. The density showed an increasing trend as the TiO2 particle size increased, while the dielectric loss (tanδ) and moisture absorption decreased with the increase of TiO2 particle size. The dielectric constant (er) and thermal conductivity (λ) decreased up to D50 = 6.5 μm and then sharply increased. Good properties with values of er = 6.8, tanδ = 0.0012 and λ = 0.533 W?m?1?K?1 were obtained in PTFE/TiO2 composites when the particle size of TiO2 was 11 μm.

Dopamine-modified TiO2 monolith-assisted LDI MS imaging for simultaneous localization of small metabolites and lipids in mouse brain tissue with enhanced detection selectivity and sensitivity.

Localization of metabolites using multiplexed mass spectrometry imaging (MSI) provides important chemical information for biological research. In contrast to matrix-assisted laser desorption/ionization (MALDI), TiO2-assisted laser desorption/ionization (LDI) for MSI improves detection of low molecular mass metabolites (<500 Da) by reducing matrix background. However, the low UV absorption of TiO2 nanoparticles and their ester hydrolysis catalytic activity hinder the detection of phospholipids and many low-abundance molecules. To address these challenges, we evaluated and optimized the material morphology and composition of TiO2. Dopamine (DA) was found to be an efficient ligand for TiO2, resulting in increased UV light absorption, higher surface pH, and formation of monolithic TiO2-DA structures. The sub-micron scale and higher surface pH of the TiO2 particle sizes led to improved detection of phospholipid signals. Compared to unmodified TiO2 sub-micron particles, the DA-modified TiO2 monolith led to 10- to 30-fold increases in the signal-to-noise ratios of a number of compound peaks. The TiO2-DA monolith-assisted LDI MSI approach has higher selectivity and sensitivity for Lewis basic compounds, such as fatty acids, cholesterols, ceramides, diacylglycerols, and phosphatidylethanolamine, when analyzed in positive mode, than traditional MALDI MS. Using this new method, over 100 molecules, including amino acids, alkaloids, free fatty acids, peptides, and lipids, were localized in mouse brain sections. By comparing the presence and localization of those molecules in young and old mouse brains, the approach demonstrated good performance in the determination of aging-related neurochemical changes in the brain.

Synergetic Photocatalytic Nanostructures Based on Au/TiO2/Reduced Graphene Oxide for Efficient Degradation of Organic Pollutants

Recently, there is crucial interest in the design and fabrication of nanocatalysts for efficient decomposition of organic pollutants in wastewater using visible light. This work reports the assembling fabrication of synergetic photocatalytic Au/TiO2/RGO nanostructures by utilizing the reduced graphene oxide (RGO) as substrate material and efficient separator for electrons and holes. The Au/TiO2 nanostructures with a ≈7 nm TiO2 particles size are dispersed uniformly on RGO nanosheets. UV–vis diffuse reflectance spectroscopy verifies that Au/TiO2/RGO nanocomposites show strong absorption of visible light. The degradation efficiency after 1 h for hydroquinone under visible light and UV light is ≈77% and ≈90%, respectively. Under visible light, the calculated apparent rates (k) of the Au/TiO2/RGO nanocomposites are 0.0112 and 0.0174 min−1 for decomposition of methylene blue and hydroquinone. That are five times greater than that of bare TiO2. The high photocatalytic activity is mainly attributed to the synergy between RGO and Au/TiO2 nanostructure. The strategy of composite nanostructures assembling on RGO is ensured to have a great practicable potential for the designing of high efficient multielement composite nanoparticles catalysts.

Preparation and properties of a long time durable superhydrophilic titanium dioxide film obtained by a sol-gel process

Abstract The superhydrophilic phenomenon of titanium dioxide (TiO2) has some potential applications. However, the superhydrophilicity can be obtained only using ultraviolet (UV) light irradiation and cannot be regained conveniently due to the energy band gap of TiO2. In this study, superhydrophilic TiO2 film on a glass substrate was prepared by a simple sol-gel method and the sol was doped with nitrogen, fluorine and polyethylene glycol (PEG). The preparation method was discussed and the film was characterized. Results show that the anatase TiO2 was obtained at about 500 °C, and the redshift of nitrogen-doped film was the largest, whereas the transmittance of fluorine-doped film was increased. The sizes of TiO2 particles in the films are uniform and the films are homogeneous except PEG-doped TiO2. Superhydrophilicity of films doped with PEG can maintain 12 days and can be regained by the irradiation of sunlight.

Effect of surfactants on the morphologies of TiO2 particles with high-performance scattering layer in dye-sensitized solar cells

A series of TiO2 powders with various morphologies were synthesized using surfactant-assisted hydrothermal method by hydrolyzing the titanium tetra-isopropoxide (TTIP) precursor. Four types of tetraalkylammonium hydroxide (TANH) surfactants such as tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), tetrapropylammomium hydroxide (TPAH), and tetrabutylammonium hydroxide (TBAH) were used before hydrothermal crystallization. The results showed that the surfactants with different alkyl chain length of tetraalkylammonium cations (TAN+) had a great influence on the morphology, particle size, and crystalline phase of TiO2 particles. Under the same experimental conditions, the surfactants of TMAH, TEAH, TPAH, and TBAH resulting in the star-, flower-, rod-, and scree-shaped TiO2 particles (TM-, TE-, TP-, and TB-TiO2), respectively. The particle sizes were decreased in the range from ∼3.6μm to ∼220nm while increasing the alkyl chain length of the surfactants. All the TiO2 powders showed an anatase phase besides the TiO2 prepared from TMAH surfactant. The photovoltaic investigations of these TiO2 samples as the scattering layer in DSSCs indicated that the TB-TiO2 based cell exhibited the excellent power conversion efficiency of 9.88%, which was also higher than that of a device which fabricated without a scattering layer (8.83%). Among these scattering layers, TB-TiO2 has the optimum particle size (∼220nm) with the highest surface area leading to the largest dye adsorption value and an excellent efficiency. In order to further increase the dye adsorption of the photoanodes, the scattering layer was prepared by mixing the large (TB-TiO2) and small sized (a-TiO2) particles as composites with different weight ratios, leading to the highest efficiency of 10.53% at TB-/a-TiO2 (2:3).

Mixed-phase TiO2 photocatalysis: correlation between phase composition and photodecomposition of water pollutants

Abstract In most cases, the combination of both anatase (up to 80%) and rutile (up to 20%) structures in a mixed-phase TiO2 semiconductor results in a better photocatalytic performance compared to the pure phase. The improvement from anatase to rutile is brought about by the enhanced transportation of photogenerated electrons. This consequently results in improved efficiency of the photoelectric and photocurrent conversion. This review highlights the effects of the morphology, particle size, and crystal structure of mixed-phase TiO2 toward the photodegradation of water pollutants. It was demonstrated that the synergistic effect between anatase and rutile TiO2 due to the interfacial electron transfer from rutile to anatase improved the photocurrent as well as the overall conversion efficiency of the anatase photoanodes. The morphologies of mixed-phase TiO2 also contributed to the final photodegradation properties. The charge and electron transfer of mixed-phase TiO2 improved the 1D structure. This consequently enables photodegradation at the visible light range.

NOx removal rate of photocatalytic cementitious materials with TiO2 in wet condition

Photocatalytic cementitious materials used in urban buildings are promising to mitigate air pollution sustainably. The changes of NO concentration in previous studies have been tested in dry condition while photocatalytic cementitious materials are mostly exposed to wetting and its water content continuously changes. This study presents the removal capacity of Nitrogen monoxide (NO) by using Titanium dioxide (TiO2) under wet condition. Under both dry and wet condition, NO removal rates were measured. For dry condition tests, dominant factors such as TiO2 particle size, TiO2 mass replacing ratio with respect to cement, and humidity were under consideration. The specimen under wet condition was subjected to the evaporation and the evolution of NO removal rate was continuously monitored. Results present that the recovery rate of removal capacity initially increased followed by the stationary phase where removal capacity stayed quasi-constant for a considerable time period in spite of continuous evaporation. Upon complete drying, the recovery rate was not fully restored due to the wetting experiment. The phenomena involved unique phases during evaporation were further discussed. The observation emphasizes that the consideration of wet condition is crucial to comprehend the NO removal capacity of photocatalytic cement-based materials in real urban environments.

Enhanced optical and hydrophilic properties of Si and Cd co-doped TiO2 thin films

In this study, preparation of Si and Cd co doped (5 mol% Si and 5–20 mol% Cd) TiO2 dip-coated thin films on glass substrates via sol–gel process have been investigated. The samples were characterized by X-ray diffraction (XRD) and Scanning electron microscopy analysis after heat treatments. XRD results suggested that adding dopants has a great effect on crystallinity and particle size of TiO2. Titania rutile phase formation was inhibited by Si4+ and promoted by Cd2+ doping. But the effect of Cd doped appeared at high concentration. Accordingly, the thin films showed various water contact angles. The water contact angles changed from 69.0° to 9.6° by changing the content of Cd doped.

Catalytic Activity of Titanium Dioxide Nanoparticles As a Non-Platinum Cathode Catalyst for Oxygen Reduction Reaction

Fuel cells offer potentially efficient, silent and low-pollution electrical power generation. Technical and economic problems have however, restricted their widespread development. One of the principal factors hampering the extensive commercialization of fuel cells is their dependence on platinum as electrocatalysts [1]. In recent years, many attempts have been made to reduce the platinum usage by introducing some metal oxide-based electrocatalysts. As a search of new metal oxide-based electrocatalysts, titanium oxide catalysts were studied for their catalytic activity during the oxygen reduction reaction (ORR) and stability in acid media, especially as a support material. It was reported that titanium oxide supported the oxygen reaction in acid [2] and alkaline [3] media. Early studies on titanium oxide catalysts showed that the catalytic activity for the ORR was low [2], however, Kim et al. [4] later showed that it depends on oxidation state, crystalline structure and work function of the titanium oxide catalysts. Moreover, although previous studies showed that the particle size of nanoparticles electrocatalysts can significantly affect their activity for the ORR [5], no work has been done to investigate the effect of particle size on catalytic performance of titanium oxide nanoparticles electrocatalysts. Therefore, due to some ambiguities and lack of knowledge in this research field, titanium oxide is worth being studied as an independent non-platinum electrocatalyst. In this study, titanium dioxide (TiO2) nanoparticle powders with four different average particle size were purchased and characterized by X-ray diffraction analysis (XRD), small-angle X-ray scattering (SAXS) and scanning electron microscopy (SEM). The SAXS profiles showed that the particle size maximum probability for TiO2 powders with average particle size of 5 nm, 18 nm, 50 nm and 100 nm were 4 nm, 12 nm, 43 nm and 96 nm, respectively. The SEM images of TiO2 nanoparticle powders showed agglomerated particles with spherical structure that this agglomeration increased with decreasing the size of particles. The XRD patterns indicated anatase and rutile phases for TiO2 nanoparticles. The diffraction intensity of crystal planes for both anatase and rutile phases increased with increasing the particle size which can impact the catalytic activity of TiO2 catalysts for the ORR. The catalytic activity of the catalysts for the ORR was evaluated using cyclic voltammograms (CVs) and linear sweep voltammograms (LSVs) in 0.1 M HClO4 acid solution at 25 ºC. The results shed light on the effect of TiO2 particle size for the ORR.

Improved electrochemical performance of Li4Ti5O12 by reducing rutile TiO2 phase impurity and particle size

Pure lithium titanate (Li4Ti5O12) powder having particle size of 100 (±38) nm has been prepared by solid-state synthesis method, using planetary ball milling at lower speed of 900 rpm as compared to high energy ball milling (3000 rpm) and characterized by X-ray diffractometer, field emission scanning electron microscopy and thermogravimetric analysis. Electrochemical performance of Li-ion battery cells is determined by charging–discharging and cyclic voltammetry tests. The material has shown very high discharge capacity of 171 and 108 mAhg−1 measured at current rates of 0.1C and 5C, respectively, as compared to 160 and 71 mAhg−1 for impure Li4Ti5O12 material (containing rutile phase of TiO2) having particle size 213 (±45) nm. Capacity retention of pure Li4Ti5O12 was 91% after 100 cycles, whereas the impure Li4Ti5O12 has shown the retention ability of 85%.

Quick cold preparation of TiO2 nanolayers on gold from P25 suspensions – film structure, voltammetric behavior and photocatalytic performance for the oxidation of EDTA under UVA-LED irradiation

Time consuming thermal treatments are a common place in the preparation of photocatalysts and their immobilization on substrates. In this work nanolayers of TiO2 were applied at room temperature on gold surfaces by simply exposing the metal during a minute to an acidic aqueous suspension of P25 TiO2 (10gL−1 in 0.1molL−1 HCl). Repulverization of the commercial semiconductor by dry grinding in a mortar increased the stability of the suspension and more than doubled the photoelectrocatalytic activity of the TiO2 nanolayer. While the average TiO2 particle size in the suspension was of 103±3nm (obtained by DLS), the less than 100nm thick TiO2 nanolayer on the gold surface was dominated by particles with diameters ranging from 20nm (anatase) to 30nm (rutile) (observed by SEM, TEM and EDS). Photooxidation experiments with EDTA −an emerging organic pollutant– revealed a linear relationship between the photocurrent and the potential applied to the TiO2 modified electrode until the saturation photocurrent was attained. For a 1.0mmolL−1 EDTA solution the integrated saturation photocurrent resulted in a net charge, repeatable from one electrode modification to another, of 38±3CLmol−1cm−2 (conditions: 100s irradiation with an UV-LED at 365nm, 91mWcm−2; 0.5V vs. Ag/AgCl applied potential). A micrometric TiO2 layer applied on gold by drop casting enhances this net charge by just 50%. Cyclic voltammograms of the ferrocyanide/ferricyanide redox probe on gold remained undisturbed (in the dark) after the application of the TiO2 nanolayer, but they became distorted with the drop-cast micrometric layer. The photoactivity of the TiO2 nanolayer lasts with little decay for many days of photoelectrocatalytic treatment of EDTA. The simple and quick modification process at room temperature can be easily scaled-up to large areas.

A preferential precursor for photocatalytically active titanium dioxide thin films: Titanium bis-ammonium lactato dihydroxide as an alternative to titanium tetra iso-propoxide

Titanium bis-ammonium lactato dihydroxide (TiBALD) precursor is used in place of the traditional sol–gel precursor, titanium tetra-isopropoxide (TTIP), to determine which precursor produces the most photocatalytically active titanium dioxide thin films. Films were deposited on glass substrates using modified sol–gel routes and the effects of non-ionic surfactant addition with Brij 58 and Brij 98 investigated. The morphology and nanostructure of the films have been assessed using SEM, XRD and Raman spectroscopy. The photocatalytic performance of the films was assessed using resazurin dye, whereby TiBALD precursor was found to produce thin films with enhanced photocatalytic efficiency, with an average rate of degradation for resazurin dye of 9.52×1012of dye molecules reduced per cm−2s−1 compared to 1.76×1012 dye molecules reduced per cm−2s−1 as for TTIP prepared films. A smaller average particle size (10–25nm) was also observed for thin films produced with TiBALD precursor, opening up potential for this precursor to be used for applications where a small TiO2 particle size is required. An overview of the differences between the two precursors for sol–gel deposition of TiO2 thin films is given within this study, including a discussion into the proposed differing decomposition mechanisms that may occur during sol–gel preparation.

Selective photoelectrocatalytic oxidation of 5-(hydroxymethyl)-2-furaldehyde in water by using Pt loaded nanotube structure of TiO2 on Ti photoanodes

Photoelectrocatalytic (PEC) synthesis of 2,5-furandicarbaldehyde (FDC) from 5-(hydroxymethyl)-2-furaldehyde (HMF) has been performed in water by using TiO2 films on Ti layer prepared by thermal annealing of Ti (Ti/TiO2) and TiO2 nanotube on Ti (Ti/TiO2NT) prepared by anodic oxidation as photoanodes. The latter ones showed better activity. In order to improve both activity and selectivity, Ti/TiO2NT was loaded with Pt by photoreduction method. 5-Formyl-2-furoic acid (FFA) was also produced by using Pt loaded Ti/TiO2NT photoanodes. The photoanodes were characterised by using XRD, SEM and XPS techniques. Allotropic phase of TiO2 photoanodes was mainly rutile, whereas trace amounts of anatase phase were found in some samples of TiO2 nanotube photoanodes. The distribution of TiO2 nanotubes on Ti are well organised. In addition, primary particle sizes of TiO2 were increased by increasing thermal treatment temperature; however primary particle sizes of TiO2 in Ti/TiO2NT are higher than that of other samples. The photoanode preparation temperature, bias and medium pH were optimised by following PEC HMF oxidation reaction. Photocatalytic and electrocatalytic HMF oxidations were also performed for comparison and negligible activities were observed. Finally efficient Pt loaded Ti/TiO2NT photoanodes were investigated for PEC selective and active FDC (selectivity up to 40%) and FFA (selectivity up to 18%) syntheses in environmental friendly conditions.

Effects of TiO2 starting materials on the synthesis of Li2ZnTi3O8 for lithium ion battery anode

Lithium zinc titanate (Li2ZnTi3O8) anode materials have been successfully synthesized using rutile-TiO2 with different particle sizes as titanium sources via a molten-salt method. Various physical and electrochemical methods are applied to characterize the effects of TiO2 particle sizes on the structures and physicochemical properties of the Li2ZnTi3O8 materials. When the particle size of TiO2 is too small (10nm), it is difficult to homogeneously mix TiO2 with the other raw materials. Thus, the final product Li2ZnTi3O8 has poor crystallinity, large particle size, small specific surface area, pore volume and average pore diameter, which are disadvantageous to its electrochemical performance. Using TiO2 with the proper particle size of 100nm as the titanium source, the Li2ZnTi3O8 (R-100-LZTO) with excellent electrochemical performance can be obtained. At 1Ag−1, 175.8 and 163.6mAhg−1 are delivered at the 1st and the 200th cycles, respectively. The largest capacities of 163, 133.3 and 122.5mAhg−1 are delivered at 2.5, 5 and 6Ag−1, respectively. The good high-rate performance of the R-100-LZTO originates from the good crystallinity, small particle size, large specific surface area and average pore diameter, low charge-transfer resistance and high Li+ diffusion coefficient.

Electrochemical Study and Characterization of an Amperometric Biosensor Based on the Immobilization of Laccase in a Nanostructure of TiO₂ Synthesized by the Sol-Gel Method.

Laccase amperometric biosensors were developed to detect the catechol compound. The laccase enzyme (LAC) immobilization was performed on nanostructures of (a) titania (TiO2); (b) titania/Nafion (TiO2/NAF) (both immobilized by the sol-gel method) and a third nanostructure, which consisted of a single biosensor composite of Nafion and laccase enzyme denoted as NAF/LAC. The Nafion was deposited on a graphite electrode and used to avoid “cracking” on the matrix. The TiO2 particle size was an average of 66 nm. FTIR spectroscopy vibration modes of different composites were determined. The electrochemical behavior of the biosensor was studied using electrochemical spectroscopy (EIS) and cyclic voltammetry (CV). The biosensor based on TiO2/NAF/LAC presented the best electro-chemical properties with regard to sensitivity, stability and detection limit after a period of 22 days.

Optimized Solid-State Reaction Process of Synthesizing Li4Ti5O12 with Improved Rate Capability for Li-Ion Batteries

Spinel Li4Ti5O12 (LTO) has been actively studied due to its predominant properties in safety issue. LTO can be synthesized by different synthesis techniques including solid-state reaction, sol-gel, high energy ball milling, hydrothermal method, spray pyrolysis, etc. Among these synthesizing methods, the solid-state reaction method is the most commercially available process. It is very important to reduce calcination temperature and time in mass production using solid-state reaction. We prepared several sets of LTOs using commercially available precursors (TiO2) which have various particle sizes. We also varied calcination temperature in each fixed TiO2 particle size. We found the optimum process condition that has the best electrochemical properties. The sizes of the TiO2 precursors are 15 nm, 25 nm, 32 nm, and 40 nm. The calcination temperatures are 700 °C, 750 °C, 800 °C, and 850 °C. The calcination time (36 hr) is too long to prepare single phase LTO at 700 °C. The single phase LTOs are obtained in all the size of the used TiO2 particle at 800 °C and 850 °C, but the LTO particles are 1 ~ 2 um, which is too large. The pure LTOs are synthesized in all the TiO2 particle size except for 15 nm at 750 °C. The calcination time was varied from 36 hr to 1hr. The rate performance is conducted in all the fabricated samples. When the calcination time is 36hr, the best capacity is obtained in the sample, which 32 nm TiO2 particle is used. At 50 C, the capacity of the sample was 88 mAh/g when the 32 nm TiO2 precursor is used. The synthesized LTO at 750 °C shows best capacity of 122 mAh/g when the calcination time is 1 hr. The best electrochemical performance was due to small particle size, resulting in fast Li-ion diffusion and larger contact area between particles. We also fabricated Li-ion capacitor using the LTO and investigated the electrochemical behaviors.

Macrophage Polarization by Titanium Dioxide (TiO2) Particles: Size Matters.

Wear particles of total joint replacements may lead to an inflammatory response driven by cells of the monocyte/macrophage lineage. Today, there is a general agreement that the continuous release of wear particles by the implant has a critical impact on periprosthetic osteolysis, which can eventually lead to aseptic loosening of the implant. The focus of this study lay on the determination of the polarization of macrophages (M0) toward the pro-inflammatory M1 phenotype or the anti-inflammatory M2-like phenotype upon exposure to differently sized TiO2 particles. The analysis was done with an in vitro model using THP-1 monocytes. It offers a direct characterization of the polarization profile of the macrophages exposed to nano- (<100 nm, measured hydrodynamic diameter: 518.5 nm) and micro- (<5 μm, measured hydrodynamic diameter: 2213 nm) sized TiO2 particles in different concentrations (4 × 104 -4 × 106 particles/mL). The polarization profile was analyzed by the quantitative assessment of relative gene expression levels as well as by the determination of specific proteins by enzyme linked immunosorbent assay (ELISA). Analysis by qRT-PCR revealed significantly elevated levels of pro-inflammatory markers such as TNF-α and CD197 at the highest concentration of stimulation by the microsized particles. This was confirmed on the protein level in the cytokine expression profile of TNF-α. Furthermore, no significant differences were found for the markers CCL22 and CD206, which are specific for the M2-like phenotype. In contrast, stimulation by nanoparticles did not induce macrophage polarization toward M1 or M2-like phenotype in any applied concentration. We conclude that the size of the particle is a determinant factor in driving the biological response of macrophages and an increased understanding of this relationship may potentially guide the design of new biomaterials.