TiO2 Nanoparticles Composites Research Articles

Catalytic activity of TiO2 nanoparticles in cyclization reactions for pyrazolone formation: DNA binding analysis via spectroscopy, X-ray crystallography, and molecular docking

This method of sustainable synthesis utilizes a range of aromatic/heterocyclic aldehydes, phenylhydrazine, and ethyl acetoacetates. The TiO2 nanoparticle catalyst facilitates cyclization reactions, yielding pyrazolone derivatives with exceptional efficiency (95–97 %) under reflux conditions at 80 °C. The current method achieves high yields of the corresponding cyclo-products in a short reaction time. A variety of physicochemical methods were employed to ascertain the chemical characteristics and structure of the synthesized heterocycles, and the geometrical structure of the well-crystallized compound (Z)-4-((5-bromofuran-2-yl)methylene)-5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one was characterized by the use of single-crystal X-ray diffraction measurement. The morphology and elemental composition of TiO2 nanoparticles were examined using SEM/EDX before and after the model reaction. A drop in the Ti (titanium) signal following the reaction indicates surface alterations. The present process provides a new and improved synthesis process for the formation of pyrazolones that is more convenient, well organized in terms of good yields, a simple handling procedure, a short reaction time, and user-friendliness compared to other surviving procedures. One of the synthesized compounds, (Z)-4-((5-bromofuran-2-yl)methylene)-5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one (2), exhibited significant DNA binding activity. This was further confirmed by a molecular docking study, which revealed a binding energy of −7.2 kcal/mol, and by analyzing the mode of interaction.

Preparation of InP quantum dots-TiO2 nanoparticle composites with enhanced visible light induced photocatalytic activity

Berry-like InP/ZnSe (core/shell) quantum dot-TiO2 nanoparticle composites were prepared via electrostatic interactions. The visible-light response InP/ZnSe quantum dot–TiO2 nanoparticle composites showed high photocatalytic activity.

Characteristics of Darcy–Forchheimer drag coefficients and velocity slip on the flow of micropolar nanofluid

AbstractThe flow of magneto‐micropolar nanofluid, that is, the composition of TiO2 nanoparticles in an organic solvent, kerosene, and the normal water past a stretchable surface has been considered. With effectiveness idea on the application in several areas, the Darcy–Forchheimer inertial drag and the second‐order velocity slip approach are vital for the current investigation. The influence of viscous, Joule and Darcy dissipations on the energy transfer cannot be neglected due to the interaction of the body forces characterized by magnetic and porosity of the medium. The dissipative heat energy with the heat generation/absorption is useful for the enhancement in the fluid temperature. Due to the complexity of the problem, a numerical solution is implemented using the in‐built code bvp5c with the help of MATLAB software. The physical properties abide by the characterizing parameters that appeared in the flow profiles are presented via graphs and the computed results for the rate coefficients are also displayed through table both for water‐ and kerosene‐based nanofluids. Finally, the main findings of the results are: the growth in the shear rate coefficient is marked due to the inclusion of second‐order slip, and an attenuation in the fluid velocity is rendered with an increase in the volume fraction whereas impact is reversed in the case of nanofluid temperature.

Composite of TiO2 nanoparticles and carbon nanotubes loaded on poly(methyl methacrylate) nanofibers: Preparation and photocatalytic performance

Carbon nanotubes (CNTs) are widely used in the preparation of composite functional materials with improved performance due to their unique electrical, mechanical properties and one-dimensional nanostructure. In this paper, the composite of TiO2 nanoparticles and acid-treated carbon nanotubes distributed on poly(methyl methacrylate) (PMMA) nanofibers was fabricated by sequential treatments of electrospinning, hydrothermal synthesis and freeze-drying. The resulting ternary composite of TiO2/CNTs/PMMA, which is featured with a specific surface area of 83.2 m2/g, effectively photodegraded a series of dyes, such as methyl blue, Rhodamine B, Sulforhodamine B and methyl orange (MO). In particular, complete degradation of MO (10 mg/L, 100 mL) was accomplished with TiO2/CNTs/PMMA (20 mg) in 40 min under UV irradiation. Moreover, the high photocatalytic activity of the ternary composite, which is superior to that of TiO2/PMMA, did not deteriorate during consecutive photodegradation tests up to ten runs. The photocatalytic mechanism of TiO2/CNTs/PMMA has been explored. The desirable high photocatalytic activity, excellent stability and easy recyclability of the ternary composite is attributed to the introduction of CNTs and the electrospun PMMA nanofiber support.

Optimizing graphene-TiO2 interface properties via Fermi level modulation for photocatalytic degradation of volatile organic compounds

The interfacial interaction between graphene and semiconductors significantly affects volatile organic compound (VOC) adsorption and charge separation. Herein, we optimize the interaction between TiO2 and reduced graphene oxide (rGO) by reducing the Fermi level of GO with Cu2+. The surface photocurrent (SPC) and surface photovoltage (SPV) of the prepared materials were tested under different atmospheres to study the effect of enhanced interfacial interactions on charge separation. The results revealed that Cu2+ treatment tended to induce the TiO2 nanoparticles to form a thicker and more uniform layer on the rGO surface. The composition of TiO2 nanoparticles and rGO generated a 2D arranged porous structure that had both hydrophobic rGO and hydrophilic TiO2 as the pore walls. The amount of adsorbed toluene for the optimized TiO2-graphene (t-TiO2/rGO) was 1.21-fold higher than that for TiO2/rGO. The SPC and SPV results showed that the optimized contact between TiO2 and rGO significantly enhanced photogenerated electron mobility and toluene-induced hole utilization. Given the advantages in adsorption and charge separation, the photocatalytic reaction rates of t-TiO2/rGO were 1.47-fold and 1.91-fold higher than those of TiO2/rGO and porous TiO2, respectively.

Enhancement of photoelectric conversion efficiency with sulfur-doped g-C3N4/TiO2 nanoparticles composites in dye-sensitized solar cells

S-doped g-C3N4/TiO2 nanoparticle composites (TCNS) were generated by successfully calcinating a compound of thiourea and TiO2 at 550 °C; these composites serve as a promising photoanode material for dye-sensitized solar cells (DSSCs) with improved efficiency. TEM, HRTEM, XRD, UV–Vis and FTIR results showed that the surfaces of TiO2 nanoparticles were coated with a thin layer of sulfur-doped g-C3N4. The corresponding photoelectrochemical properties of the fabricated DSSCs were also studied. The DSSCs based on the TCNS photoelectrode shows a ratio of 4.87% in converting light into electricity, a short-circuit photocurrent of 10.41 mA cm−2, and an open-circuit voltage of 0.65 V, qualities which were well above those of DSSCs based on un-doped TCNS. The significant enhancement in DSSC performance is mainly due to the suppression of the recombination of electron–hole (e−–h+) pairs, suppression which also leads to an increase in open-circuit photovoltage, as well as photocurrent density under short circuit by the layer of sulfur-doped g-C3N4. Additionally, electrochemical impedance spectroscopy analysis proved that the electron transfer resistance is considerably reduced, and this reduction increases the power conversion efficiency.

Premixed Stagnation Flame Synthesized TiO2 Nanoparticles with Mixed Phases for Efficient Photocatalytic Hydrogen Generation

Mixed-phase TiO2 nanoparticles (10–20 nm) composed of rutile, anatase, and srilankite phases are prepared through a one-step flame synthesis method. The phase composition of TiO2 nanoparticles can be easily tuned by changing the flame conditions such as the gas flow rates of the fuel, oxygen, and argon carrier. The optimized anatase/rutile/srilankite TiO2 sample with as low as 0.1 wt % of Pt cocatalyst exhibits remarkable photocatalytic H2 generation rate of 21.9 mmol h–1 g–1 and an apparent quantum efficiency (AQE) of 39.4% at 360 nm, higher than those of anatase/rutile or anatase TiO2. The less studied srilankite phase is first time investigated for photocatalytic H2 generation. It is revealed that the relatively low content of srilankite phase in TiO2 could efficiently promote charge separation and transportation. It is remarkable that, compared to the commercial P25 TiO2, the flame-made TiO2 significantly improves Pt reduction and dispersion owing to the oxygen vacancies and surface defects. The optim...

Fabrication and characterization of poly(vinyl alcohol)-TiO2 nanocomposite films for orthopedic applications

Poly(vinyl alcohol) (PVA) is reinforced with TiO2 nanoparticles in order to enhance thermo-mechanical stabilities, surface characteristics and osteoblastic cell adhesion. PVA–TiO2 nanocomposite films with desirable mechanical, thermal and biocompatible properties are fabricated through solution casting method followed by de-hydrothermal cross-linking treatment. The composition of TiO2 nanoparticles was standardized to achieve mechanically stable nanocomposite films, based on tensile strength measurements composition of TiO2 is determined as optimal at 3wt%. PVA–TiO2 nanocomposite films were characterized by Scanning electron microscopy, Energy dispersive spectroscopy, Atomic force microscopy, Ultra violet and Fourier transform infrared spectroscopic techniques. Elemental mapping studies substantiate incorporation of TiO2 nanoparticles within the PVA matrix. Dimensional stability evaluated by soaking films in SBF for 24h insinuates the role of TiO2 in the direction of controlling degree of swelling. In-vitro bioactivity test and cell adhesion results also predict that presence of TiO2 is advantageous to enhance apatite growth and promote cell-substrate interaction. SEM studies illustrate improved surface morphology of PVA–TiO2 nanocomposite film with homogenously distributed TiO2 nanoparticles, which help to enhance thermo-mechanical behavior. TiO2 nanoparticles construct cell-adhesive hydrophilic nano-domains that act as potential cell adhesion sites and promotes osteointegration. Bio compatibility studies proved that thermally cross-linked PVA is non-toxic in relation to PVA cross-linked with glutaraldehyde. Cytotoxicity and cell adhesion of nanocomposite films evaluated through cell viability (MMT) assay and crystal violet staining revealed that PVA-3wt% TiO2nanocomposite could act as an excellent composite and hence suitable to be used in bone implant applications.

Synthesis and characterization of TiO2@SiO2–Ag nanocomposites towards photocatalytic degradation of rhodamine B and methylene blue

Titanium dioxide (TiO2) as photocatalyst is widely used in water purification, because many organic compounds can be decomposed and mineralized by oxidation and reduction processes taking place on the surface of TiO2. In this study, the composite of TiO2 nanoparticles (NPs) @ mesoporous silica nanoparticles (MSNPs) (TiO2@SiO2) were prepared by the sol–gel method. The prepared TiO2@SiO2 nanocomposite was modified by decorating silver nanoparticles (Ag NPs) (TiO2@SiO2–Ag) using a hydrothermal method. The TiO2@SiO2–Ag nanocomposite was characterized by field emission scanning electron microscope (FE-SEM), energy dispersive X-ray spectroscopy (EDAX), X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy and UV–Visible spectroscopy. The FE-SEM analysis revealed that the Ag NPs are uniformly spread on the TiO2@SiO2 nanocomposite which could highly enhance its photocatalytic activity. XRD analysis also confirmed the presence of Ag nanoparticles on the surface of TiO2@SiO2 nanocomposite. The TiO2@SiO2–Ag nanocomposite exhibited better photocatalytic performance in terms of degrading rhodamine B and methylene blue with the photo catalytic degradation efficiency of 92 and 85 % respectively under direct sunlight illumination. These results disclosed that the TiO2@SiO2–Ag nanocomposite can be exploited as a potential photocatalyst towards the degradation of dye studies.

Titanium mesh supported TiO2 nanowire arrays/Nb-doped TiO2 nanoparticles for fully flexible dye-sensitized solar cells with improved photovoltaic properties

TiO2 nanowire arrays/2.4 mol% Nb-doped TiO2 nanoparticles composites were synthesized on Ti-mesh substrates using a hydrothermal approach for fully flexible dye-sensitized solar cells that exhibited good 7.20% conversion efficiency.

Formation of rod-like nanostructure by aggregation of TiO2 nanoparticles with improved performances

To improve the performance of titanium dioxide (TiO2)-based devices, many efforts have been made to prepare nanostructures with composite of TiO2 nanoparticles and nanorods. In this work, a novel rod-like TiO2 nanostructure was obtained via a controllable hydrolysis process. Morphology and structure analysis showed that the rod-like nanostructure was a well-aligned aggregate of nearly spherical TiO2 nanoparticles. Rod-like TiO2 nanoparticle aggregates were fabricated on a primary TiO2 nanoparticle-based layer without the use of template, and formed a hierarchical TiO2 composite film together. The photocatalytic activity of the TiO2 film with rod-like nanoparticle aggregates was evaluated by the degradation of methylene blue. The antibacterial activity of fabricated hierarchical TiO2 film was assessed against Staphylococcus aureus. The photoelectrochemical property of this film as the photoanode in assemble dye-sensitized solar cell was also tested. Compared with randomly distributed nanoparticle-based TiO2 film, the hierarchical TiO2 film exhibited improved performance of photocatalysis, antibacterial activity and photoelectric conversion.

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.

Performance of dye-sensitized solar cells based on various sensitizers applied on TiO2-Nb2O5 core/shell photoanode structure

The present investigation described the performance of dye-sensitized solar cells (DSSCs) based on various sensitizers applied on TiO2-Nb2O5 core/shell photoanode film. The novel photoanodes were prepared using composite of TiO2 nanoparticles (TNPs) and TiO2 nanorods (TNRs) as core (TNPRs) layer with Nb2O5 shell coating. As well, tantalum pentoxide (Ta2O5), a blocking layer applied over the core/shell film. The DSSCs were fabricated based on various sensitizers namely zinc phthalocyanine, indoline, indigo carmine, zinc porphyrin, N719, coumarin NKX-2700, polymer dye, quantum dots (QDs), perylene and squaraine. The I–V characteristics of the DSSCs, photocurrent density (Jsc), open-circuit voltage (Voc), fill factor (FF), and photoconversion efficiency (PCE) were determined under illumination of AM 1.5 G. Electrochemical impedance spectroscopy (EIS) analysis is carried out to study the charge transport and life-time of charge carriers at photoanode/dye/electrolyte interface of the DSSCs. The I–V and EIS results explicated that the core/shell with blocking layers were able to alleviate the electron transport and suppressed charge recombination at photoanode/dye/electrolyte interface of the DSSCs. Concerning the sensitizers, PCE of the DSSCs exemplify the order N719 > zinc porphyrin > coumarin NKX-2700 > indoline > squaraine > QDs > zinc phthalocyanine > perylene > polymer dye > indigo carmine dye. The results of the present work demonstrated that among the sensitizers studied, N719 showed the highest PCE and fill factor. Besides, the metal-free organic sensitizers (coumarin NKX-2700 and indoline) exhibited comparable PCE as compared to N719.

ATR-FTIR spectroscopy as a tool to probe surface adsorption on nanoparticles at the liquid–solid interface in environmentally and biologically relevant media

Given the importance of nanoparticle surface composition in nanotoxicology, analytical tools that can probe nanoparticle surfaces in aqueous media are crucial but remain limited. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy is a technique capable of in situ characterization of the liquid-solid interface to probe surface adsorption on nanoparticle surfaces in environmentally and biologically relevant media. Furthermore, given that the interfacial region in these media is dynamic, ATR-FTIR spectroscopy facilitates monitoring these dynamics by interrogating a layer of immobilized nanoparticles coated on the ATR element while changing the overlying aqueous phase. The molecular information acquired from this technique allows for the determination of the adsorption mode, including conformational and structural changes of the coordinating ligand, and can directly measure ligand displacement reactions. Furthermore, in some cases, ATR-FTIR spectroscopy can be used as a quantitative surface analytical tool. In this article, we briefly review the fundamentals of the technique and then provide several examples of using ATR-FTIR spectroscopy to probe nanoparticle surfaces in general with respect to: (i) the adsorption of different environmentally and biologically relevant coordinating ligands; (ii) competitive ligand adsorption and; (iii) the determination of kinetic and thermodynamic parameters. We have also investigated surface adsorption of TiO2 nanoparticles in different biological media typically used for toxicity studies and show that the surface composition of TiO2 nanoparticles depends to a large extent on the composition of the medium due to surface adsorption. This result has important implications for the interpretation of toxicity data as well as inter-comparisons between toxicity studies.

Electrochemical properties of TiO2 nanoparticle/nanorod composite photoanode for dye-sensitized solar cells

A unique composite of TiO2 nanoparticles (NPs) and nanorods (NRs) has been used to fabricate a photoelectrode for developing dye-sensitized solar cells (DSSCs) with higher sensitivity. The TiO2 nanorods were synthesized using a mechanical process, in which electrospun TiO2 nanofibers was grinded in a controlled way to obtain uniform size distribution. The characteristics of electron transport, recombination lifetime and charge collection were investigated by intensity-modulated photocurrent spectroscopy (IMPS) and intensity-modulated photovoltage spectroscopy (IMVS). Photoelectrodes prepared with the composites of NRs and NPs showed significant improvements in electron transportation compared to only NP photoelectrodes, which would enhance the photovoltaic performance of DSSCs. IMPS and IMVS measurements show that fast electron transport and slightly decreased recombination lifetime resulted in the improvement of efficiency. The highest energy conversion efficiency obtained from the photoelectrodes fabricated with the as-prepared rutile TiO2 nanofibers at 5 wt% NR content was up to 6.1% under AM1.5G solar illumination. The results demonstrate that the composite nanostructure can take advantage of both the fast electron transport of the nanorods and the high surface area of the nanoparticles.

Preparation and Characterization of Stearic Acid-Modified Iron-Doped TiO<sub>2</sub> Nanoparticles

In this study, TiO2 nanoparticles composites were prepared by the micro emulsion method, above of all samples were characterized by FT-IR, XRD. Photo activities of Fe-TiO2, TiO2 were evaluated by degradation of oil-bearing wastewater. The results show that the photo activity of Fe-TiO2 was more than that of TiO2; the best presence of iron ion dopants in TiO2 was 0.04%. Used stearic acids as the surface modification agent, Fe-TiO2 were modified by situ surface modification. The results showed that the optimum conditions of stearic acid-Fe - TiO2 :Temperature (20°C), the modified time (45 min), the ratio modifier dosage tomagnetitemass (4%). Then we did the initial exploration of Fe-TiO2 Powder that was modified by stearic acid.

TiO<sub>2</sub> Photo-Catalysis Degradation of COD and Chroma for Chemical Wastewater Treatment

In this study, TiO2 nanoparticles composites were prepared by the micro emulsion method. Used the chemical wastewater as degradation products to evaluate the degradation performance of TiO2 photo-catalysis. The results indicated that TiO2 had photo-catalysis efficiency under the light, the optimal dosing of TiO2 was 1g/L, optimal pH value was 10, and COD of initial concentration was 1000 mg/L.

Synthesis and photovoltaic performance of reduced graphene oxide–TiO2 nanoparticles composites by solvothermal method

In the present work, the reduced graphene oxide (RGO)–TiO2 nanocrystals composites are prepared by a simple solvothermal method, and then are used as the photo-anodes in dye-sensitized solar cells (DSSCs). The result shows that the decoration of the P25 nanoparticles with reduced graphene oxide will favor for the promotion of the conversion efficiency in DSSCs. The photo-anodes films of 0.75wt% RGO–TiO2 composites reach the best conversion efficiency of 5.5%, and it’s of 31% higher than that of the pure P25 photo-anodes films, which lies in the fact that the reduced graphene oxide in the TiO2 composites may reduce the intrinsic resistance and prolong the life-time of the electron transfer in DSSCs.

Nanocomposites Consisting of Titanium Dioxide Nanoparticles and Oligonucleotides

The use of various nanoparticles is a promising way to solve the current problem of drug delivery in medicine and biology. Nanocomposites consisting of titanium dioxide and oligonucleotides noncovalently attached to nanoparticles through the polylysine linker (TiO2 x PL-DNA) have been designed to deliver of DNA fragments into cells. Three forms of TiO2 nanoparticles (amorphous, anatase, and brookite) were used for construction of nanocomposites. The size, morphology, and chemical composition of TiO2 nanoparticles and TiO2 x PL-DNA nanocomposites were characterized. DNA fragments in the proposed nanocomposites were shown to retain their ability to form complementary complexes. TiO2 x PL-DNA nanocomposites independently on the form of nanoparticles were shown by confocal microscopy to penetrate into HeLa cells without any transfection agents and physical impact. The presented type of nanocomposites can be applied in the thriving technology of drug delivery to achieve high therapeutic and biological efficacy.

Dispersion Characteristics of TiO2 Particles Coated with the SiO2 Nano-Film by Atomic Layer Deposition

Deposition of SiO2 nanofilm on TiO2 particles using atomic layer deposition method is reported. The SiO2 film was prepared at the room temperature using the chemicals Si(OC2H5)4, C2H5N and H2O as precursor, catalyst and reactant gas, respectively. The thickness, composition and uniformity of the SiO2 coating on TiO2 surface were characterized by FESEM, HRTEM, EDS and XPS measurements. In HRTEM analysis, the growth rate was about 0.33 angstroms/cycle. EDS and XPS analysis showed the surface composition of TiO2 nanoparticles was silicon oxide. Zeta potential, particle size distribution and sedimentation test results indicated that dispersibility of coated nanoparticles was higher than that of uncoated nanoparticles because of the electrostatic repulsion between the SiO2-coated layers on the surface of TiO2 nanoparticles. These results suggested that the SiO2 coating could modify the surface characteristics of the TiO2 nanoparticles and improve the dispersibility of the TiO2 primary nanoparticles.