Titania Nanofibers Research Articles

Multiple negative differential resistance in perovskite (CH3NH3PbI3) decorated electrospun TiO2 nanofibers

Polyvinyl alcohol and titanium dioxide nanofibers have been synthesized through the electrospinning method. CH3NH3PbI3 microcrystals were deposited over TiO2 nanofiber through a chemical bath deposition method. In this report, we have discussed the electrical properties of the CH3NH3PbI3 decorated TiO2 nanofibers. Multiple negative differential resistance (multiple peaks) was observed in perovskite (CH3NH3PbI3) decorated polyvinyl alcohol-titanium dioxide composites nanofibers when 2 V bias was applied. Polyvinyl alcohol-titanium dioxide composite nanofibers have been characterized by scanning electron microscope, fourier transform infrared spectra and X-ray diffraction. “Write–read–erase–read” sequence of the electrical response of the composites was probed to determine the memory applications. Electrochemical impedance spectroscopy (EIS) was investigated to determine the charge confinement in the perovskite decorated nanofiber in the high- and low-conducting states.

Extraction of Small RNAs by Titanium Dioxide Nanofibers.

MicroRNAs (miRNAs) are small RNAs, that bind to mRNA targets and regulate their translation. Functional study of miRNAs and exploration of their utility as disease markers require miRNA extraction from biological samples, which contain large amounts of interfering compounds for downstream RNA identification and quantification. The most common extraction methods employ either silica columns or TRIzol reagent, but these approaches afford low recovery for small RNAs, possibly due to their short strand lengths. Here, we describe the fabrication of titanium dioxide nanofibers and the optimal extraction conditions to improve miRNA recovery from biological buffers, cell lysate, and serum.

Evaluation the effects of humidity and other process parameters on TiO2 Nanofibers by RSM (CCD) and experimental

Nanofibers are one of the most widely used materials in various industrial sectors. Among them Titanium Dioxide (TiO2) nanofibers are excelled, moreover they are environmentally friendly and have shown that they have diverse industrial applications. The physical structure of this fiber (diameter and surface characteristics) is a key effective factor on its behavior for corresponding applications. In this study, the effects of different factors influencing the diameter of TiO2 nanofibers were analyzed and quantified using two statistical analyses namely the Response Level Method (RSM) and the Composite Central Design (CCD) method. The preparation parameters of polymer synthesis including the electrical potential, the distance between electrodes tips, flow rate, and ambient humidity were studied. Results marked polymer concentration as the most important factor affecting the diameter of the nanofibers. However the diameter was almost independent from flow rate, and hence marked as the least effective factor. Furthermore, as humidity increased, the diameter of the fibers decreased significantly and surface roughness increased as demonstrated in the SEM and FESEM images. Since the relative humidity has intense impact on the structural properties of titanium dioxide nanofibers, humidity condition of synthesis space must be strictly controlled and kept below a threshold (38%).

Facile fabrication of electrospun black titania nanofibers decorated with graphitic carbon nitride for the application of photocatalytic CO2 reduction

Black titania nanofibers (NFs) were electrospun and subjected to a simplified two-step sintering process at low pressure. Disordered “black” titania structures developed; Ti-O exhibited a blue shift and electrons occupied oxygen vacancies. Black titania NFs were coated with graphitic carbon nitride (g-C3N4) via sintering in an Ar atmosphere; the facile fabrication of metal-free heterostructures using non-toxic H2O reaction medium was reported to participate in photocatalytic CO2 reduction under UV–vis light irradiation, showing CO and CH4 yields of 5.19 and 1.65 μmol/g, respectively. The heterostructured g-C3N4/black titania NFs indicated 1.8-fold higher production of CO2 conversion (CO and CH4) compared to that of g-C3N4 while the heterostructure showed 2.12 times higher production of CO2 conversion (CO and CH4) compared to that of black titania NFs. Finally, the reusability test of the heterostructure was conducted upto the fourth cycle. Throughout the entire electronic band, heterostructured g-C3N4/black titania NFs exhibited increased absorption at 470 nm, even at the lowest photoluminescence intensity compared to that of g-C3N4. The calculated Fermi level and conduction/valence bands showed that the heterostructured g-C3N4/ black titania NFs exhibited proper band position associated with a sufficient kinetic overpotential of (△Ea,CH4) 0.54 eV, for successful production of both CO and CH4. This confirms that g-C3N4 and black titania NFs were well-connected via their interfaces so that this metal-free heterostructured g-C3N4/black titania NFs has proven its possibility to yield its CO2 conversion products.

Improved electrocatalytic activity of ethanol oxidation over Pd/TiO2 nanofibers-carbon black nanocomposite

Herein, titanium dioxide nanofibers (TiO2 NFs) were successfully prepared using sol-gel combined electrospinning method and subsequent calcination at 600 °C. The TiO2 NFs were used for preparation of TiO2 NFs-carbon black composite including Pd nanoparticles (Pd/TiO2 NFs-C). The prepared samples were characterized by field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR), thermal gravimetric analysis (TGA) and N2 adsorption-desorption isotherm (BET). The FE-SEM showed that the polyvinyl pyrrolidone/titanium tetraisopropoxide composite (average fiber diameter: 125 nm) and TiO2 NFs (average fiber diameter: 48 nm) were obtained. TEM micrograph showed a relatively good dispersion of the Pd nanoparticles with average diameters at about 31 nm over TiO2 NFs-C composite. Using XRD, anatase and rutile crystalline phases for the TiO2 NFs and face center cubic (fcc) structure for Pd were identified in the nanocomposite. The dispersed Pd nanoparticles onto the TiO2 NFs-C showed a specific electro-catalytic activity in EOR with j = 17.6 mA cm−2, 6.4-fold improvement than that of traditional Pd/C catalyst.

Emissions and exposures of graphene nanomaterials, titanium dioxide nanofibers, and nanoparticles during down-stream industrial handling

Today, engineered nanomaterials are frequently used. Nanosized titanium dioxide (TiO2) has been extensively used for many years and graphene is one type of emerging nanomaterial. Occupational airborne exposures to engineered nanomaterials are important to ensure safe workplaces and to extend the information needed for complete risk assessments. The main aim of this study was to characterize workplace emissions and exposure of graphene nanoplatelets, graphene oxide, TiO2 nanofibers (NFs) and nanoparticles (NPs) during down-stream industrial handling. Surface contaminations were also investigated to assess the potential for secondary inhalation exposures. In addition, a range of different sampling and aerosol monitoring methods were used and evaluated. The results showed that powder handling, regardless of handling graphene nanoplatelets, graphene oxide, TiO2 NFs, or NPs, contributes to the highest particle emissions and exposures. However, the exposure levels were below suggested occupational exposure limits. It was also shown that a range of different methods can be used to selectively detect and quantify nanomaterials both in the air and as surface contaminations. However, to be able to make an accurate determination of which nanomaterial that has been emitted a combination of different methods, both offline and online, must be used.

Enhancing the Antibacterial Performance of Titanium Dioxide Nanofibers by Coating with Silver Nanoparticles

The potential of titanium dioxide (TiO2) nanofibers in antibacterial applications has received wide attention. This interest is further enhanced by the possible incorporation of silver (Ag) to form...

Study of How Photoelectrodes Modified by TiO2/Ag Nanofibers in Various Structures Enhance the Efficiency of Dye-Sensitized Solar Cells under Low Illumination

Dye-sensitized solar cells (DSSCs) are low-cost solar cells belonging to the thin-film photovoltaic cell type. In this study, we studied the photovoltaic performances of DSSCs based on titanium dioxide (TiO2) nanofibers (NFs) containing silver (Ag) nanoparticles (NPs) under low illumination. We used the sol-gel method with the electrospinning technique to prepare the TiO2 NFs containing Ag NPs. Herein, we used two ways to add TiO2/Ag NFs to modify the photoelectrode successfully and enhance the performance of DSSCs. One way was that the TiO2/Ag NFs were mixed with pristine TiO2; the other way was that the TiO2/Ag NFs were seeded beside the TiO2 colloid layer as an additional layer on the photoelectrode of the DSSC. According to this experiment, the photovoltaic conversion efficiency of the DSSC which had TiO2/Ag NF seeded as an additional layer on the photoelectrode (5.13%) was increased by 28% compared to the DSSC without the photoelectrode modification (3.99%). This was due to the suppression of electron recombination and the more effective utilization of the light radiation by adding the TiO2/Ag NFs. Because of the good conductivity of Ag, the electrons were quickly transported and electron recombination was reduced. In addition, the photovoltaic conversion efficiency of the DSSC which had TiO2/Ag NF seeded as an additional layer on the photoelectrode increased from 5.13% to 6.23% during the decrease in illumination from 100 mW/cm2 to 30 mW/cm2; however, its photovoltaic conversion efficiency decreased to 5.31% when the illumination was lowered to 10 mW/cm2.

Fabrication of aptamer modified TiO2 nanofibers for specific capture of circulating tumor cells

Herein, we developed an inexpensive titanium dioxide (TiO2) nanofiber substrate for efficient and selective capture of circulating tumor cells (CTCs) from mimic patients’ samples. The TiO2 nanofiber substrates were fabricated by electrospinning in combination with the calcination process. The surface of nanofiber substrates was modified with the anti-adhesion molecule, bovine serum albumin (BSA) and the nucleolin aptamer AS1411, wherein, aptamer AS1411 specifically binds to the nucleolin protein overexpressed on the membrane surface of cancer cells. The formed TiO2 nanofiber substrates exhibited high efficacy and specificity to capture nucleolin positive cells through synergistic topographic interactions. Using the rare number of cell capture experiments, the capture efficiency of up to 75 % was achieved on the surface of the nanofiber substrate for rare number target cells spiked in the white blood cells (WBCs) from 1 mL whole blood samples. In conclusion, this study highlighted the potential of the TiO2-BSA-biotin-AS1411 nanofiber substrate as a highly efficient platform to realize the selective and specific capture of rare CTCs in the clinical settings.

Surface-Modified Titanium Dioxide Nanofibers with Gold Nanoparticles for Enhanced Photoelectrochemical Water Splitting

High-stability, high-efficiency, and low-cost solar photoelectrochemical (PEC) water splitting has great potential for hydrogen-energy applications. Here, we report on gold/titanium dioxide (Au/TiO2) nanofiber structures grown directly on a conductive indium tin oxide substrate, and used as photoelectrodes in PEC cells for hydrogen generation. The titanium dioxide nanofibers (TiO2 NFs) are synthesized using electrospinning, and are surface-modified by the deposition of gold nanoparticles (Au NPs) using a simple photoreduction method. The structure and morphology of the materials were characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The surface plasmon resonance (SPR) of the Au NPs was investigated by ultraviolet-visible (UV-Vis) diffuse reflectance spectroscopy. The PEC properties of the as-prepared photoelectrodes were measured. The obtained photoconversion efficiency of 0.52% under simulated-sunlight illumination by a 150 W xenon lamp of the Au/TiO2 NFs structure with 15 min UV irradiation for Au NP deposition was the highest value from comparable structures. Working photoelectrode stability was tested, and the mechanism of the enhanced PEC performance is discussed.

Differences in cytotoxicity of lung epithelial cells exposed to titanium dioxide nanofibers and nanoparticles: Comparison of air-liquid interface and submerged cell cultures

Air Liquid Interface (ALI) system has emerged as a useful tool for toxicity evaluation of nanomaterials related to inhalation since the system mimics the aerosol exposure. We compared the biological responses of lung epithelial cells exposed to titanium dioxide (TiO2) nanofibers and nanoparticles in ALI and submerged cell cultures systems. Cells were exposed to 2 and 10 μg/cm2 for 24 h, 48 h and 72 h and LDH release, TiO2 internalization, DNA-double strand breaks (DSBs) and ROS production were assessed. LDH release was similar in both systems and particles had higher cytoplasmic uptake in submerged systems. Both TiO2 types were located in the cytoplasm but nanofibers had nuclear uptake regardless to the system tested. Cells exposed to TiO2 nanofibers had higher DSBs in the ALI system than in submerged cell cultures but cells exposed to TiO2 nanoparticles had similar DSBs in both systems. ROS production was higher in cells exposed to TiO2 nanofibers compared to cells exposed to TiO2 nanoparticles. In conclusion, cytotoxicity of lung epithelial cells was similar in ALI or submerged cell cultures, however cells exposed to TiO2 nanofibers displayed higher toxicity than cells exposed to TiO2 nanoparticles.

MnO2 encapsulated electrospun TiO2 nanofibers as electrodes for asymmetric supercapacitors

We report a facile technique to fabricate manganese dioxide (MnO2) encapsulated titanium dioxide (TiO2) nanofiber heterostructure for its use as an electrode material in aqueous electrolyte based asymmetric supercapacitor (SC). MnO2 coated TiO2 nanofibers, prepared by electrospinning and post-hydrothermal process exhibited superior electrochemical properties in aqueous Na2SO4 electrolyte. The MnO2 shell with average thickness of approximately 10 nm contributed to the high electrochemical performance for charge storage by redox reaction and intercalation mechanisms, while the anatase phase TiO2 core provided an easy pathway for electronic transport with additional electrochemical stability over thousands of charge–discharge cycles. An asymmetric SC designed from the MnO2–TiO2 nanofiber electrode and single walled carbon nanotubes electrode showed high operating voltage window (2.2 V) with maximum gravimetric capacitance of 111.5 F g−1.

Hollow Au@TiO2 porous electrospun nanofibers for catalytic applications.

Catalytically active porous and hollow titania nanofibers encapsulating gold nanoparticles were fabricated using a combination of sol–gel chemistry and coaxial electrospinning technique. We report the fabrication of catalytically active porous and hollow titania nanofibers encapsulating gold nanoparticles (AuNPs) using a combination of sol–gel chemistry and coaxial electrospinning technique. The coaxial electrospinning involved the use of a mixture of poly(vinyl pyrrolidone) (PVP) and titania sol as the shell forming component, whereas a mixture of poly(4-vinyl pyridine) (P4VP) and pre-synthesized AuNPs constituted the core forming component. The core–shell nanofibers were calcined stepwise up to 600 °C which resulted in decomposition and removal of the organic constituents of the nanofibers. This led to the formation of porous and hollow titania nanofibers, where the catalytic AuNPs were embedded in the inner wall of the titania shell. The catalytic activity of the prepared Au@TiO2 porous nanofibers was investigated using a model reaction of catalytic reduction of 4-nitrophenol and Congo red dye in the presence of NaBH4. The Au@TiO2 porous and hollow nanofibers exhibited excellent catalytic activity and recyclability, and the morphology of the nanofibers remained intact after repeated usage. The presented approach could be a promising route for immobilizing various nanosized catalysts in hollow titania supports for the design of stable catalytic systems where the added photocatalytic activity of titania could further be of significance.

3D Titania Nanofiber-Like Webs Induced by Plasma Ionization: A New Direction for Bioreactivity and Osteoinductivity Enhancement of Biomaterials

In this study, we describe the formation method of web-like three-dimensional (3-D) titania nanofibrous structures coated on transparent substrate via a high intensity laser induced reverse transfer (HILIRT) process. First, we demonstrate the mechanism of ablation and deposition of Ti on the glass substrates using multiple picosecond laser pulses at ambient air in an explicit analytical form and compare the theoretical results with the experimental results of generated nanofibers. We then examine the performance of the developed glass samples coated by titania nanofibrous structures at varied laser pulse durations by electron microscopy and characterization methods. We follow this by exploring the response of human bone-derived mesenchymal stem cells (BMSCs) with the specimens, using a wide range of in-vitro analyses including MTS assay (colorimetric method for assessing cell metabolic activity), immunocytochemistry, mineralization, ion release examination, gene expression analysis, and protein adsorption and absorption analysis. Our results from the quantitative and qualitative analyses show a significant biocompatibility improvement in the laser treated samples compared to untreated substrates. By decreasing the pulse duration, more titania nanofibers with denser structures can be generated during the HILIRT technique. The findings also suggest that the density of nanostructures and concentration of coated nanofibers play critical roles in the bioreactivity properties of the treated samples, which results in early osteogenic differentiation of BMSCs.

Hybrid acrylic nanocomposites with excellent transparency and hardness/toughness balance

The composite nanofibers were used as reinforcement in acrylic polymer for the overall enhancement of thermo-mechanical properties, adhesion between fibers and matrix, and fracture toughness of the final nanocomposite since acrylic materials lack of this feature. So, a good balance between hardness/toughness and transparency is obtained with the addition of poly (vinyl butyral) (PVB) and titania (TiO2) nanofibers simultaneously and controlling their contents. Specifically, when compared to that of pure acrylic polymer, the fracture toughness of the PMMA nanocomposite apparently increased 55 % with the addition of 3 wt.% titania nanoparticles, while the produced nanocomposite maintained high transmittance above 75–80% in the visible domain. The transmission spectrum modelling of the reinforced fiber materials and hybrid acrylic composites using Mie scattering theory for different particle sizes and particle content is presented. The calculated transmission coefficients versus wavelength are compared with the experimental ones.

Titania Nanofiber Scaffolds with Enhanced Biointegration Activity-Preliminary In Vitro Studies.

The increasing need for novel bone replacement materials has been driving numerous studies on modifying their surface to stimulate osteogenic cells expansion and to accelerate bone tissue regeneration. The goal of the presented study was to optimize the production of titania-based bioactive materials with high porosity and defined nanostructure, which supports the cell viability and growth. We have chosen to our experiments TiO2 nanofibers, produced by chemical oxidation of Ti6Al4V alloy. Fibrous nanocoatings were characterized structurally (X-ray diffraction (XRD)) and morphologically (scanning electron microscopy (SEM)). The wettability of the coatings and their mechanical properties were also evaluated. We have investigated the direct influence of the modified titanium alloy surfaces on the survival and proliferation of mesenchymal stem cells derived from adipose tissue (ADSCs). In parallel, proliferation of bone tissue cells—human osteoblasts MG-63 and connective tissue cells - mouse fibroblasts L929, as well as cell viability in co-cultures (osteoblasts/ADSCs and fibroblasts/ADSCs has been studied. The results of our experiments proved that among all tested nanofibrous coatings, the amorphous titania-based ones were the most optimal scaffolds for the integration and proliferation of ADSCs, fibroblasts, and osteoblasts. Thus, we postulated these scaffolds to have the osteopromotional potential. However, from the co-culture experiments it can be concluded that ADSCs have the ability to functionalize the initially unfavorable surface, and make it suitable for more specialized and demanding cells.

Highly efficient mixed-halide mixed-cation perovskite solar cells based on rGO-TiO2 composite nanofibers

In this investigation, the electrospun reduced graphene oxide-titanium oxide composite nanofibers as an electron transporting materials have been employed for the perovskite solar cells. The synthesized electron transporting materials have been used for the fabrication of mixed-cation lead mixed-halide (FAPbI3)0.85(MAPbBr3)0.15 perovskite solar cells. The influence of reduced graphene oxide on titanium oxide nanofibers and their morphological and electronic properties have been investigated in detail. The optimized device having FTO/Bl-TiO2/rGO4–TiO2/(FAPbI3)0.85(MAPbBr3)0.15/spiro-MeOTAD/Au configuration exhibited a η = 17.66% power conversion efficiency with an open circuit voltage of 1.070 V, short circuit current density of 22.16 mAcm−2 and fill factor of 0.754. This obtained efficiency is much higher than that of mesoporous-titanium oxide (14.39%), pristine-titanium oxide nanofibers (15.82%) and other reduced graphene oxide-titanium oxide composite nanofibers based electron transporting materials.

High Temperature Resistant Separator of PVDF-HFP/DBP/C-TiO2 for Lithium-Ion Batteries

To improve the thermal shrinkage and ionic conductivity of the separator for lithium-ion batteries, adding carboxylic titanium dioxide nanofiber materials into the matrix is proposed as an effective strategy. In this regard, a poly(vinylidene fluoride-hexafluoro propylene)/dibutyl phthalate/carboxylic titanium dioxide (PVDF-HFP/DBP/C-TiO2) composite separator is prepared with the phase inversion method. When the content of TiO2 nanofibers reaches 5%, the electrochemical performance of the battery and ion conductivity of the separator are optimal. The PVDF-HFP/DBP/C-TiO2 (5%) composite separator shows about 55.5% of porosity and 277.9% of electrolyte uptake. The PVDF-HFP/DBP/C-TiO2 (5%) composite separator has a superior ionic conductivity of 1.26 × 10 −3 S cm−1 and lower interface impedance at room temperature, which brings about better cycle and rate performance. In addition, the cell assembled with a PVDF-HFP/DBP/C-TiO2 separator can be charged or discharged normally and has an outstanding discharge capacity of about 150 mAh g−1 at 110 °C. The battery assembled with the PVDF-HFP/DBP/C-TiO2 composite separator exhibits excellent electrochemical performance under high and room temperature environments.

Visible Light Photocatalytic Functional TiO2/PVDF Nanofibers for Dye Pollutant Degradation

AbstractThe photodegradation of poly(vinylidene fluoride) (PVDF)/titanium oxide (TiO2) nanofibers under visible light is described, something that has not been previously reported in the literature. Visible light photocatalytic electrospun PVDF/TiO2 nanofiber webs with anatase TiO2 concentration varying from 0% to 20% (0%, 1%, 3%, 5%, 10%, and 20%) are produced, and their ability to degrade a toxic pollutant, Rhodamine B (RhB), is studied. Photodegradation study using UV–vis spectroscopy on PVDF/TiO2 nanofiber webs (with TiO2 concentration of 20%) shows that 80% of RhB is degraded within 6 h at the wavelength of 546 nm, which clearly falls within the visible spectra. The color of RhB solvent catalyzed by PVDF/TiO2 nanofiber webs gradually changes from red to orange, then to yellow, further to light yellow till colorless, which suggests the complete photodegradation of RhB under visible light. To estimate the rate of photodegradation, the reaction constant k is calculated. Based on the k value, PVDF/TiO2 nanofiber webs with 20% TiO2 concentration show the highest degradation rate compared to other PVDF/TiO2 nanofiber webs and pure TiO2 nanoparticles. This study proves the viability of TiO2‐based nanofibers to have catalytic capabilities under low‐energy visible light.

In situ growth of manganese oxide nanosheets over titanium dioxide nanofibers and their performance as active material for supercapacitor

In recent years, electrochemical energy devices, i.e. batteries, fuel cells, solar cells, and supercapacitors, have attracted considerable attention of scientific community. The architecture of active materials plays a crucial role for improving supercapacitors performance. Herein, titanium dioxide (TiO2) nanofibers (1D) have been synthesized by electrospinning process and used as a backbone to manganese dioxide (MnO2) nanosheets (2D) growth through hydrothermal method. This strategy allows the obtaining of 1D/2D heterostructure architecture, which has demonstrated superior electrochemical performance in relation to pristine MnO2. The highest electrochemical performance is due to the synergic effect between the metal oxides, where TiO2 nanofibers provide electrochemical stability for active MnO2 phase. Thus, the designed TiO2@MnO2 structure can reach maximum specific capacitance of 525 F·g−1 at a current density of 0.25 A·g−1, and it demonstrates an excellent stability by retaining 81% of the initial capacitance with coulombic efficiency of 91%. Therefore, the novel architecture of TiO2@MnO2 based on nanofibers and nanosheets exhibits superior electrochemical properties to be used in supercapacitor applications.