As-synthesized TiO2 Nanoparticles Research Articles

Green Synthesis of TiO2 Using Impatiens rothii Hook.f. Leaf Extract for Efficient Removal of Methylene Blue Dye.

In this work, TiO2 nanoparticles (NPs) were effectively synthesized by a green method using the Impatiens rothii Hook.f. leaf (IL) extract as a capping and reducing agent. The as-synthesized TiO2 NPs were characterized by different characterization methods such as the Brunauer-Emmett-Teller (BET) analysis, high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), diffused reflectance spectroscopy (DRS), and X-ray diffraction (XRD) and Raman spectroscopy. The specific surface area from BET analysis was found to be 65 m2/g. The average crystallite size from XRD analysis and average particle size from SEM analysis were found to be ∼11 and ∼25 nm, respectively. The Raman spectroscopy and XRD results showed that the biosynthesized (IL-TiO2) nanoparticles were purely anatase phase. XPS analysis illustrated the formation of Titania with an oxidation state of +4. The DRS study showcased that a blue-shifted intense absorption peak of IL-TiO2 (3.39 eV) compared to the bulk material reported in the literature (3.2 eV). HRTEM micrograph showed the presence of grain boundary with d spacings of 0.352, 0.245, and 0.190, which correspond to the lattice planes of (101), (004), and (200), respectively. From the EDX analysis, the weight percents of titanium and oxygen were found to be 54.33 and 45.67%, respectively. The photoinduced degradation of methylene blue (MB) dye was investigated in the presence of biosynthesized IL-TiO2 NPs photocatalyst. The effect of parameters like catalyst dosage (30 mg/L), initial concentration of MB (15 ppm), pH (10.5), and contact time (100 min) on the removal efficiency was optimized. The maximum photodegradation efficiency under the optimized conditions was found to be 98%.

Thermal properties investigation of paraffin wax/titania nanocomposites as phase change materials

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.

Mechanical and Thermophysical Properties of Epoxy Nanocomposites with Titanium Dioxide Nanoparticles

The introduction of nanoparticles and their homogeneous distribution in the polymer matrix, as well as their size, can have a significant effect on the mechanical properties of composite materials. In this work, we studied the mechanical characteristics of TiO2/epoxy nanocomposites with different contents and sizes of nanoparticles. The preparation of nanocomposites was carried out by a stepwise curing (at 90 and 160 °C) of ED-20 dianic epoxy resin in the presence of an aromatic hardener with the addition of titanium (IV) dioxide nanoparticles preliminarily synthesized by the plasma-chemical method. Ultrasonic dispersion was used to achieve a uniform distribution of nanoparticles in the polymer matrix. The chemical and phase composition, the structure of the as-synthesized TiO2 nanoparticles, and the resulting epoxy nanocomposites were characterized by elemental analysis, X-ray diffraction, transmission and scanning electron microscopy, and infrared spectroscopy. The mechanical properties of the nanocomposites were determined by the static tensile test, and the impact toughness was determined by the Charpy method. The glass transition temperature and thermal stability of the TiO2/epoxy nanocomposites were studied by thermal analysis methods. The formation of an interfacial layer between the TiO2 nanoparticles and an epoxy matrix has been shown for the first time by spectral methods. It is shown that the mode of curing and ultrasonic dispersion used, as well as varying the content and dispersity of the TiO2 nanoparticles, make it possible to obtain epoxy nanocomposites with simultaneously improved deformation-strength characteristics and impact strength values.

Synthesis of TiO2 Nanoparticle-Embedded SiO2 Microspheres for UV Protection Applications

Exposure to ultraviolet (UV) radiation induces many serious health issues. Because of serious health concerns, there is an urgent need to develop UV filters with better efficacy and high safety. For this purpose, titanium dioxide (TiO2) nanoparticles are the most desirable materials due to their excellent UV protection abilities. The use of TiO2 as sunscreens has raised some concerns about potential risks due to the formation of TiO2-mediated free radicals. Herein, TiO2 nanoparticles have been successfully embedded in silica (SiO2) microspheres using the emulsion synthesis method. The as-synthesized TiO2 nanoparticles embedded in silica microspheres have shown excellent UV protection ability. TiO2 nanoparticles embedded in silica microspheres suppress the photocatalytic properties compared to bare TiO2 nanoparticles, and these results indicate that TiO2-embedded silica microspheres are promising UV protection materials for sunscreen.

Green and Low-Cost Synthesis of TiO2 Nanoparticles for Methanol Detection

TiO2 nanoparticles synthesis using Ficus benghalensis leaf extract via green synthesis approach, were characterized using XRD, FTIR, EDAX analysis and SEM. The present study explores the use of as-synthesized TiO2 nanoparticles for the detection of methanol by spin-coating as-synthesized TiO2 nanoparticles (~ 100 nm thickness) over n-type Si substrate as an active material with Au sputtered electrodes (~ 60 nm). The change in resistivity and electrical conductivity when exposed to the analyte clearly evidenced the detection at low operating temperature is recorded. The response curve of transient resistance vs. time was recorded at different working temperatures (50-200 ºC) and the device tested multiple times exhibited the same behaviour affirming the reproducibility with stability of thin film sensor is reported.

Biomimetic TiO2-chitosan/sodium alginate blended nanocomposite scaffolds for tissue engineering applications.

The study is aimed to synthesize potent metal oxide based biomimetic nanocomposites to overcome the risk associated with artificial bone tissue engineering. High purity TiO2 nanoparticles are synthesized via hydrothermal route. A biomimetic nanocomposite scaffolds containing chitosan-sodium alginate (4: 4) blended with three different (0.5, 1, and 1.5wt%) concentrations of hydrothermally synthesized TiO2 nanoparticles are obtained by solvent casting technique. The physico-chemical and thermal degradation properties of as-synthesized TiO2 nanoparticles and their nanocomposite scaffolds are analyzed. In-vitro cytotoxicity and biocompatibility of the prepared TiO2 nanoparticles and nanocomposites are tested against human bladder tumor (UC6) and osteosarcoma (MG-63) cell lines. Antibacterial property is tested against Escherichia coli and Staphylococcus aureus. These studies reveal that TiO2 nanoparticles and polymeric nanocomposites contain good physico-chemical and mechanical properties for enhanced in-vitro biocompatibility suitable for biomedical applications. Biomimetically prepared chitosan-sodium alginate scaffold containing TiO2 nanoparticles (1wt%) is found to exhibit superior biocompatibility for bone tissue engineering applications.

Facile Hydrothermal Preparation of Flower-Like Tio2 Nanostructure With Enhanced Photocatalytic Activity

This paper demonstrated the preparation of flower-like TiO2 nanostructures by low temperature hydrothermal process from TiO2 nanoparticles. The as-synthesized TiO2 nanoparticles and flower-like TiO2 nanostructures were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and N2 adsorption-desorption measurements. The flower-like TiO2 nanostructures possessed good crystallinity, showed fairly large surface area of 220 m2/g and exhibited better photocatalytic degradation of rhodamine B than TiO2 nanoparticles under simulated solar radiation.

Enhanced photocatalytic activity of wool fibers having titanium dioxide nanoparticles formed inside their cortex

A wool-TiO2 nanoparticle composite material having TiO2 nanoparticles both infiltrated in the matrix between macrofibrils inside cortical cells of wool fibers and grafted on the fiber surface is obtained in this study, and the wool-nanoparticle composite material is found to have highly photocatalytic activities with an extremely narrow band gap of 2.8 eV. The wool fibers are obtained using three successive technical steps: wool fibers are swollen by using lithium bromide, then saturated with tetrabutyl titanate ethanol solution and subsequently treated in boiling water. It was demonstrated that the chemical bonds formed between the as-synthesized TiO2 nanoparticles and the wool fibers swollen by lithium bromide include C−Ti4+(Ti3+), N−Ti4+(Ti3+), O−Ti3+, and S−Ti4+(Ti3+) bonds. The modified wool fibers have shown markedly improved photocatalytic efficiency due to their enhanced visible light absorption capability, which is much better than the (N-doped) TiO2 coated wool fibers. In contrast, TiO2 modified wool fibers swollen by using formic acid have poorer photoactivity, this might be due to the elimination of trivalent titanium between TiO2 nanoparticles and the wool fibers.

TiO2 Nanoparticles Incorporated Peptide Appended Perylene Bisimide-Based Nanohybrid System: Enhancement of Photo-Switching Behavior

A peptide appended perylene bisimide (PBI)-based new hydrogel has been discovered in phosphate buffer medium having the pH ranging from 7.00 to 9.00. This peptide appended PBI-derivative shows interesting photoswitching property in the aggregated state. This gel is thoroughly characterized by UV–visible absorption and fluorescence spectroscopy, field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD), and rheological studies. TiO2 nanoparticles are also prepared by using a protein amino acid, glutamic acid, in water medium. The as-synthesized TiO2 nanoparticles exhibit usual photoswitching behavior. An organic–inorganic hybrid nanomaterial is prepared by incorporating the as-synthesized TiO2 nanoparticles into the fibrillar gel network of the native gel. This TiO2–PBI-based hybrid soft material shows a characteristic of nanofiber and nanoparticle combination in their nanoscale coassembled state as it is evident from the respec...

Characterization and stability of TiO2 nanoparticles in industrial dye stuff effluent

ABSTRACTStability studies were conducted in different solutions (deionized water (DI), NaCl, CaCl2, and MgCl2) at different pH. Agglomeration and zeta potential were influenced by ionic strength, type of electrolyte, and the presence of dye stuff. The Derjaguin–Landau–Verwey–Overbeek (DLVO) theory was used to analyze the stability and/or agglomeration of the nanoparticles in the different solutions. Repulsive or attractive forces stipulated by the DLVO theory were used to quantitatively discuss the results. The increase in ionic strength increased agglomeration which was linked to pHpzc, as there were minimal electrostatic repulsions at the pzc, yet the attractive van der Waals forces were dominant. Addition of the dye stuff significantly decreased the agglomeration as the dye stuff changed the overall zeta potential of TiO2 nanoparticles to negative across the entire pH which improved stability as there were particle–particle repulsions. Monovalent and divalent cations were compared and Ca2+ increased the mean diameter of nanoparticles as it effectively decreased the EDL of the nanoparticles, thus enhancing agglomeration. The DLVO theory was successful at explaining, in terms of the interaction energies between nanoparticles, the phenomena that caused either agglomeration or stability of the as-synthesized TiO2 nanoparticles in the different solutions.

The optoelectronic properties and applications of solution-processable titanium oxide nanoparticles

In this study, the surface modified TiO2 nanoparticles have been prepared through microwave-assisted reaction with oleic acid as surfactant. The as-synthesized TiO2 nanoparticles reveal uniform particle size distribution and high dispersibility in organic solvents which can be easily integrated into solution-process. The organic capped TiO2 (OC-TiO2) has been applied as filler for LED encapsulant and electron collection layer for organic solar cells. With 1.0wt% loading of TiO2 nanoparticles, the refractive index (RI) of TiO2/silicone composites increase from 1.51 for neat silicone to 1.575. As a result, a high-power LED encapsulated with this composite showed more than 9% increase in the light output. Moreover, the organic solar cell with the OC-TiO2 as electron collection layer shows an enhanced long-term durability due to the hydrophobic property of OC-TiO2.

The Effect of Heat Treatment of TiO2 Nanoparticles on Photovoltaic Performance of Fabricated DSSCs

The present work focuses on the synthesis of mixed phase TiO2 nanoparticles with reduced band gaps without even being doped. The synthesis was carried out by chemical route followed by heat treatments at different temperatures to favor rutile incorporation in anatase network. The significance of different heat treatment temperatures on the phase composition of TiO2 nanoparticles and its effect on optical band gap and the photovoltaic performance are analyzed. The thermal analysis, phases, morphology, and energy band gap of as-synthesized TiO2 nanoparticles have been characterized by DTA/TG, x-ray diffraction, field-emission scanning electron microscope, transmission electron microscope, and UV-Vis-NIR, respectively. The results show the presence of rutile (~15 nm) and anatase phases (~17 nm) in “as-synthesized” TiO2 nanoparticles. TiO2 nanoparticles are heat treated for 2 h at 200, 400, and 600 °C in air. It is observed that heat treatment results in higher photoactivity in visible region of the solar radiation and the material demonstrated high photovoltaic performance in conjunction with N-719. The optical band gap values are found to be in the range of 2.59-2.88 eV. The dye-sensitized solar cells (DSSCs) fabricated by TiO2 nanoparticles, heat treated at 600 oC show the energy conversion efficiency (η) of 6.08% with high photo current density (Jsc) of 11.76 mA/cm2. The work highlighted in this paper represents the realization of simple method of achieving low band gap semiconductors without being doped, for DSSCs applications.

Photocatalytic degradation of Eriochrome Black T dye using well-crystalline anatase TiO2 nanoparticles

Well-crystalline anatase TiO2 nanoparticles were prepared by facile solution process and characterized in terms of their morphological, structural, optical and photocatalytic properties. The detailed studies confirmed that the as-synthesized nanoparticles are well-crystalline, grown in high density and exhibiting good optical properties. For photocatalytic degradation, Eriochrome Black T (EBT) dye was used as a model compound and about 82% of photo-degradation of EBT dye was achieved in 90min under UV light irradiation. The kinetic studies revealed that EBT photo-degradation follows pseudo-first order reaction kinetics and rate constant was found to be 0.017min−1. In addition to this, by comparing the photocatalytic performance with other commercially available catalysts (PC-50, PC-500, commercial ZnO), it was observed that the as-synthesized TiO2 nanoparticles exhibited superior photocatalytic performance.

Facile Growth and Characterization of TiO2 Nanoparticles for Photocatalytic Degradation of 2,3-Dichlorophenol: Experimental Optimization and Comparison with Commercial TiO2

This paper reports the facile synthesis and characterizations of TiO2 nanoparticles by simple sol-gel ultrasonication followed by annealing process. The prepared nanoparticles were characterized in terms of their morphological and structural properties and utilized as efficient photocatalyst for the photocatalytic degradation of 2,3-dichlorophenol (2,3-DCP). The as-synthesized TiO2 nanoparticles were annealed at 350 degrees C for various time intervals (3-5 h) and by morphological and photocatalytic performances, it was found that the nanoparticles annealed for 5 hrs exhibits best morphological and photocatalytic properties. To optimize the photocatalytic reaction parameters, several experiments based on catalyst dose (0.25-1.00 g/L), pH of the solution (pH = 3-11) and initial concentration (10-100 mg/L) have been performed using commercially available TiO2 (PC-105). Under optimized conditions, the photocatalytic performance of synthesized TiO2 nanoparticles and TiO2 (PC-105) was compared and it was found that the synthesized nanoparticles exhibits better photocatalytic properties as compared to the commercially available TiO2 (PC-105).

Chemical synthesis of TiO2 nanoparticles and their inclusion in Ni–P electroless coatings

The work addresses the preparation of Ni3P3TiO2 nanocomposite coatings on mild steel substrate by the electroless technique. Nanosized TiO2 particles were first synthesized by the precipitation method and then were codeposited (4 g/l) into the Ni3P matrix using alkaline hypophosphite reduced EL bath. The surface morphology, particle size, elemental composition and phase analysis of as-synthesized TiO2 nanoparticles and the coatings were characterized by field emission scanning electron microscopy (FESEM), energy-dispersive analysis of X-ray (EDAX) and X-ray diffraction (XRD). Coatings with 20 µm thickness were heat treated at 400 °C for 1 h in argon atmosphere. The morphology, microhardness, wear resistance and friction coefficient characteristics (ball on disc) of electroless Ni3P3TiO2 nanocomposite coatings were determined and compared with Ni3P coatings. The results show that as-synthesized TiO2 nanoparticles are spherical in shape with a size of about12 nm. After heat treatment, the microhardness and wear resistance of the coatings are improved significantly. Superior microhardness and wear resistance are observed for Ni3P3TiO2 nanocomposite coatings over Ni3P coatings.

Low-temperature synthesis of water-dispersible anatase titanium dioxide nanoparticles for photocatalysis

Water-dispersible anatase TiO2 nanoparticles were synthesized at a low temperature (80°C) without using surfactants via the mechanism of electrostatic stabilization. The water-dispersible TiO2 nanoparticles solution was stable and no precipitation occurred after 3months. Photocatalytic evaluation demonstrated that the as-synthesized TiO2 nanoparticles possess excellent quinoline degradation performance (a 2.33×10−2min−1 apparent reaction rate constant comparing to 1.22×10−2min−1 for P25) and recycle stability (the photocatalytic activity remained 96.6% of the initial activity after four cycles of repetitive uses). These could be attributed to the small size and good water-dispersibility of the as-synthesized TiO2 nanoparticles that led to large specific surface area and easy photogenerated electron–hole transportation.

Photocatalytic degradation of quinoline in aqueous TiO2 suspension

Anatase TiO2 nanoparticles with an average size of 16nm were synthesized via a modified sol–gel method and were employed to degrade quinoline under UV irradiation (λ=365nm). The influence of reaction parameters such as TiO2 dosage, initial quinoline concentration and pH was investigated. Under the optimized reaction condition, 91.5% photodegradation efficiency of quinoline was achieved. When the TiO2 nanoparticles were reused for four times, the photodegradation efficiency was still as high as 90.6%. The analysis of the organic intermediates suggested that superoxide radical (O2) predominantly attacked the pyridine ring of quinoline leading to the formation of 2-aminobenzaldehyde, 2-quinolinone, 4-quinolinone; while the hydroxyl radical (OH) contributed much less by attacking benzene rings resulting in the formation of 5-hydroxyquinoline. The photocatalytic performance of the as-synthesized TiO2 nanoparticles was comparable to the commercial P25. A tentative mechanism was postulated for the photodegradation of quinoline over TiO2 nanoparticles.

Detecting Ultra-Violet Radiation by Using Titanium Dioxide Nanoparticles

In this paper sensitivity of chemically synthesized titanium dioxide (TiO2) nanoparticles to ultra-violet (UV) radiation is investigated. For this purpose three types of ultra-violet photodetectors were fabricated, one with as-synthesized TiO2 nanoparticles, another one with TiO2 nanoparticles annealed at 600℃, and the third one with TiO2 nanoparticles annealed at 800℃. In each case the annealing time duration was one hour. The photodetectors were fabricated on glass slides where on them a thin layer of fluorine doped tin oxide (FTO) was deposited by spray pyrolysis. The results show that all photodetectors are sensitive to UV radiation where the photodetectors fabricated from annealed TiO2 nanoparticles are more sensitive than the photodetectors fabricated from as-synthesized TiO2 nanoparticles.

Enhanced Photocatalytic Activity of Nitrogen Doped TiO2 Anatase Nano-Particle under Simulated Sunlight Irradiation

Nitrogen doped TiO2 nanoparticles were successfully synthesized by the addition of ammonia water. The as-synthesized TiO2 nano-particles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–visible diffuse reflectance spectra (UV-vis DRS). It was found that doping with nitrogen could effectively inhibit the phase transformation of TiO2 from anatase to brookite, enhance light absorption in visible region. The photocatalytic efficiency of phenol on N doped TiO2 nano-particle was higher than that of undoped and P25 TiO2, which could be attributed to the small crystallite size, high crystallinity, intense light absorption in visible region and narrow band gap energy. Further, the formation mechanism of N doped TiO2 was proposed.

Large scale photochemical synthesis of M@TiO2 nanocomposites (M = Ag, Pd, Au, Pt) and their optical properties, CO oxidation performance, and antibacterial effect

Well-dispersed M@TiO2 (M = Ag, Pd, Au, Pt) nanocomposite particles with a diameter of 200–400 nm can be synthesized on a large scale by a clean photochemical route which does not require any additives using spherical rutile nanoparticles as a support. The sizes of Pt, Au, and Pd nanoparticles formed on the surface of TiO2 particles are about 1 nm, 5 nm, and 5 nm, respectively, and the diameter of Ag nanoparticles is in the range 2–20 nm. Moreover, the noble metal nanoparticles have good dispersity on the particles of the TiO2 support, resulting in excellent catalytic activities. Complete conversion in catalytic CO oxidation is reached at temperatures as low as 333 and 363 K, respectively, for Pt@TiO2 and Pd@TiO2 catalysts. In addition, the antibacterial effects of the as-synthesized TiO2 nanoparticles, silver nanoparticles, and Au@TiO2 and Ag@TiO2 nanocomposites have been tested against Gram-negative Escherichia coli (E. coli) bacteria. The results demonstrate that the presence of the TiO2 matrix enhances the antibacterial effect of silver nanoparticles, and the growth of E. coli can be completely inhibited even if the concentration of Ag in Ag@TiO2 nanocomposite is very low (10 μg/mL).