Titanium Dioxide Nanowires Research Articles

Engineering Fano resonances in plasmonic metasurfaces for colorimetric sensing and structural colors

In this paper, we present the design and fabrication of a plasmonic metasurface based on titanium dioxide (TiO2) nanowire arrays integrated with plasmonic layers. The structure is engineered to produce Fano resonances within the visible spectrum, resulting from the coupling of localized surface plasmon resonances, lattice modes, and nanowire's optical modes. Experimentally, we show that by tuning the geometrical features of the metasurface, such as the length, diameter, and period of the nanowires, a high-quality factor single peak can be achieved in the reflection spectra, resulting in vivid structural colors in bright field. To our knowledge, this is the first demonstration of such vivid colors with nanowire arrays in bright field reflections. When characterized by refractive index fluids around the refractive index of water, the plasmonic metasurface also showed great potential for biochemical colorimetric sensing. The best design demonstrated a bulk sensitivity of 183 nm/RIU with high Q resonance features and linear changes in color values using image processing.

Selective oxidation of glycerol mediated by surface plasmon of gold nanoparticles deposited on titanium dioxide nanowires

This paper describes an alternative method for the in situ synthesis of gold nanoparticles (AuNPs) with a particle size of less than 3 nm, using nanoreactors formed by reverse micelles of 1,4-bis-(2-ethylhexyl) sulfosuccinate sodium (AOT) and nanoparticle stabilization with l-cysteine, which favor the preparation of nanoparticles with size and shape control, which are homogeneously dispersed (1% by weight) on the support of titanium dioxide nanowires (TNWs). To study the activity and selectivity of the prepared catalyst (AuNPs@TNWs), an aqueous solution of 40 mM glycerol was irradiated with a green laser (λ = 530 nm, power = 100 mW) in the presence of the catalyst and O2 as an oxidant at 22 °C for 6 h, obtaining a glycerol conversion of 86% with a selectivity towards hydroxypyruvic acid (HA) of more than 90%. From the control and reactions, we concluded that the Ti–OH groups promote the glycerol adsorption on the nanowires surface and the surface plasmon of the gold nanoparticles favors the selectivity of the reaction towards the hydroxypyruvic acid.

Defect-engineering-based titanium dioxide nanowires for artificial optoelectronic synapses

Artificial optoelectronic synapses, as a typical neuromorphic device, have garnered significant attention due to their concurrent capabilities in processing visual perception and memory. In this study, we propose an artificial optoelectronic synapse with a dual-terminal metal-semiconductor-metal (Au/TiO2/Cr/Au) structure. By modulating the concentration of oxygen vacancy defects in TiO2, the device exhibits a significant persistent photoconductivity (PPC) effect. The devices successfully simulated the synaptic behaviors, including paired-pulse facilitation (PPF), short-term plasticity (STP), long-term plasticity (LTP), and the learning-forgetting process. In addition, the device array has the capability to recognize optical signals and exhibits an obvious response gradient under different optical powers. This demonstrates its ability to adaptively detect optical signals and simulate human visual memory.

Hybrid 1D titanium oxide nanowire – Reduced graphene oxide nanocomposites as efficient catalyst support for PEMFC

With hydrogen being projected as the fuel of the future, proton exchange membrane fuel cells (PEMFC) have regained prominence as a zero-emission power source. Researchers are focusing on replacing the conventional carbon support used for the platinum catalysts with alternative materials to improve the durability of the electrocatalysts. Despite being a potential candidate, graphene-based materials have been limited by their lower limiting current density, possibly due to restacking of the graphene sheets. On this note, we introduced varying quantities of metal-oxide based 1D TiO2 nanowires to reduced graphene oxide (rGO) support and analysed their impact on the performance of the electrocatalyst. The optimized support with an initial content of 60 wt.% GO and 40 wt.% TiO2 exhibited higher mass transfer limiting current density, after Pt incorporation (Pt/TiO2-rGO), in comparison to the other composites. The catalyst showed higher retention in electrochemical surface area (1.42 times) and mass activity (1.48 times) compared to the commercial Pt/C after an accelerated durability test. Polarization studies carried out in a 25 cm2 fuel cell fixture exhibited a peak power density close to 720 mW cm−2 and almost two times higher current density (at 0.6 V) than the catalyst without TiO2. These results reaffirm the role of TiO2 in overcoming the limitations of graphene-based support.

Photoelectrochemical properties of doped TiO2 nanowires grown by seed-assisted thermal oxidation

Titanium dioxide Nanowires (NWs) are particularly interesting because of their very high surface/volume ratio and their photocatalytic activity allows them to be used in a myriad of applications. This manuscript presents a study of nanowires grown on a conductive substrate making use of a seed-assisted thermal oxidation process. To obtain doped NWs, before the oxidation, metallic titanium was doped with Fe (or Cr) by ion implantation technology. Analyses showed good quality Rutile phase and light absorption in the visible range. Transport properties of the NWs/electrolyte junction were investigated by using linear sweep voltammetry and electrochemical impedance spectroscopy. They allowed us to measure the photovoltage and the barrier height of the junction. We also evaluated the density of hole trap states at the interface during illumination. Electrical results indicate that the formation of deep levels, induced by doping, influences the electron concentration in the TiO2 and the transport properties.Graphical abstract

Improved antimicrobial activities of biphasic titania nanowires against Gram-negative and Gram-positive bacteria

This research focused on the synthesis of biphasic titania nanowires from commercially available anatase titania via hydrothermal method to improve its antimicrobial activity. The electron microscope scanning (SEM) showed that the titania nanowires structures were successfully synthesized with width varying from 17 to 96 nm and length from 0.7 to 8 μm. The titania nanowires have biphasic structure of brookite and anatase, as observed from the X-ray diffraction pattern. The band gap was calculated from the ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS) spectra at 3.3eV, which is between the range of pure anatase and pure brookite band gap. The crystallite size of the titania nanowires was calculated using the Scherer equation and showed a much smaller crystallite size compared to commercial titania. The antimicrobial activity of the titania nanowires was then investigated against gram-negative and gram-positive bacteria. They exhibited improved antimicrobial activity against the Gram-negative Pseudomonas aeruginosa and Escherichia coli along with Gram-positive Bacillus subtilis. Interestingly, their inhibition zone was comparable to the antibiotic tetracycline. Meanwhile, the commercial titania did not show any antimicrobial activity on any tested bacterial strains. The improved antimicrobial activity of the titania nanowires was attributed to its biphasic phase, small particle size, and its one-dimensional morphology.

Enhanced dielectric properties of titanium dioxide/epoxy nanocomposites with different nanofiller shape

In this study, three different shapes of titanium dioxide, namely nanoparticles, nanowires, and nanosheets, were blended into a bisphenol-A epoxy resin. The dielectric properties of the epoxy nanocomposites were measured to investigate whether the shape of the nanofiller affects the behavior of the epoxy resin. Firstly, titanium dioxide nanowires and titanium dioxide nanosheets were synthesized. Secondly, three different fillers were added to the epoxy resin to obtain three types of nanocomposites. Finally, the performance of these epoxy nanocomposites were evaluated including complex permittivity dependence on frequencies, DC volume resistivity, AC breakdown strength, and thermally stimulated discharge current. Results indicate that different shapes of titanium dioxide fillers have varying effects on the characteristics of the epoxy resin. It was observed that the shape of the nanofiller influences the amount of trapped charge in samples which subsequently impacts the overall performance of the epoxy composite.

A novel approach for adsorption of organic dyes from aqueous solutions using a sodium alginate/titanium dioxide nanowire doped with zirconium cryogel beads.

The presence of organic dyes in wastewater raises significant environmental and human health concerns, owing to their high toxicity. In light of this, a novel adsorbent material with porous cryogel architecture was developed and employed for the effective removal of organic dyes from an aqueous solution. Initially, a titanium dioxide nanowire doped with zirconium HZTO was synthesized by the hydrothermal process. Subsequently, the beads (SA/HZTO) of sodium alginate and HZTO were successfully prepared through a cross-linking process, employing Ca2+ ions as the crosslinking agent. Structural analysis of SA/HZTO beads was performed using FTIR, SEM, and EDX techniques. We systematically examined the impact of different conditions, including the initial dye concentration, pH, contact time, and adsorbent dosage, on the adsorption process. Batch experiments, both in signal and binary systems, were conducted to rigorously assess the dye adsorption capabilities. Kinetic modeling revealed that the adsorption process adhered to the pseudo-second-order kinetic model. Remarkably, the prepared beads exhibited impressive adsorption capacities of 26 and 29mg/g toward methylene blue (MB) and safranin (SF), respectively. SA/HZTO beads have demonstrated excellent adsorption properties, offering a promising avenue for the development of low-cost, efficient, and reusable adsorbent to remove dyes from wastewater.

Silver-infused TiO2 nanowires and unveiling their potential for superior wastewater dye remediations.

Silver infused ultrathin TiO2 nanowires (NWs) were synthesized via a single step solvothermal approach. The crystallinity, structure, and morphology were determined to understand the physicochemical nature of the nanocomposites. The catalytic efficiency of the newly synthesized nanocatalysts was tested for the textile waste treatment taking methylene blue (MB) as model pollutant under solar light irradiations. Nearly 96% photodegradation efficiency for MB was achieved within 20 min. Furthermore, the recyclability of the photocatalyst was also studied, and the material remained stable and effective up to four consecutive runs. RESEARCH HIGHLIGHTS: Precise size-controlled synthesis of Ag-incorporated titania nanowires (ATNWs) Controlled aspect ratios, with tunable lengths and diameters (100-3 nm) via precursor and surfactant optimization Demonstrated ATNWs' efficiency in degrading toxic dye, methylene blue (MB) 96% photodegradation efficiency for MB achieved within 20 min using 3 nm thick annealed TiO2 NWs Recyclability efficiency of photocatalyst, which remained stable and effective for up to four consecutive runs.

(Invited) Surface and Structural Dependent Reactivity of Alkylphosphonic Acids-Modified Titanium Oxide Nanostructures with 2-Chloroethyl Ethyl Sulfide Under Visible Light Excitation

Synthesizing novel TiO2 nanomaterials are valuable for heterogeneous reactivity to address toxic chemical remediation. Titanium oxide nanoflowers (comprising assemblies of nanorods) and nanowires have been synthesized in which photocatalytic reactivity with 2-chloroethyl ethyl sulfide (2-CEES) has been significantly enhanced under visible light (1000 nm > λ > 400 nm) excitation. Enhancement of photooxidation with reaction rates of 99 and 168 µmol/g/h (quantum yields of 5.07 x 10-4 and 8.58 x 10-4 molecules/photon) were observed for TiO2 synthesized in the presence of two different alkylphosphonic acids (C14H29PO3H2 and C9H19PO3H2). Additionally, H2Ti2O5‧H2O nanowires were synthesized and capable of highly efficient hydrolysis of the carbon-chlorine (C-Cl) bond of 2-CEES without light at a reaction rate of 279.2 µmol/g/h due to high surface area and chemical nature of the titanate structure. These observations are correlated with: 1) generation of new surface defects/states (i.e. oxygen vacancies) as a result of TiO2 grafting by alkyl phosphonic acid that may serve as reaction active sites; 2) better light absorption by assemblies of nanorods in comparison to individual nanorods, 3) surface area differences, and 4) the exclusion of OH groups due to the formation surface functionalization with alkylphosphonic acids via Ti-O-P bonds on the TiO2. These robust materials can be used for highly efficient surface decontamination.

Exceptional formaldehyde oxidation at room temperature on Co single-atom functionalized TiO2 nanowires via highly effective O2 activation

O2 activation is vital for catalyzing the oxidation of formaldehyde (HCHO). Despite the high O2 activation capabilities demonstrated by noble metal catalysts, their practical application is impeded by their exorbitant cost. Herein, Co single atoms were successfully incorporated into titanium dioxide nanowires (TiO2-NWs). Furthermore, the key step in the HCHO catalytic oxidation process was elucidated through in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) and density functional theory (DFT) calculations. Finally, the intricate O2 activation mechanism was explored, revealing the catalyst’s exceptional performance in ambient HCHO oxidation. Notably, it outperformed commercial TiO2 (TiO2-P25) by 13.3 times and Co-supported TiO2-P25 by 1.9 times. Co single atoms facilitated the conversion of O2 into superoxide (O2-), significantly reducing the reaction barrier of dioxymethylene to formate. This superior O2 activation was attributed to the active nature and unsaturated electronic configuration of Co single atoms. This study provides a novel, cost-effective strategy for creating HCHO elimination catalysts with accessible nonnoble transition metals.

High toughness, UV & blue light shielding and antibacterial bio-based PEF/TiO2 nanowires composites for packaging application

As a candidate of fossil-based poly(ethylene terephthalate) (PET), bio-based poly(ethylene 2,5-furandicarboxylate) (PEF) that could be converted from renewable resources has attracted attention from academia and industry. Here, we prepare a series of new type of PEF/TiO2 NWs composites from 2,5-furandicarboxylic acid (FDCA), ethylene glycol (EG), titanium dioxide nanowire (TiO2 NWs, diameter∼100 nm, length∼20 µm) and dipentaerythritol (Di-PE) via in-situ polymerization. The TiO2 nanowires (0.5∼10 wt‰ based on PEF) and Di-PE (3 mol‰ based on FDCA) were added as fillers and extenders. TiO2 nanowires were distributed in the PEF uniformly, shown by SEM. Compared with pure PEF, the Tg and thermal stability of all nanocomposites got improved. And the impact strength of nanocomposites could reach 60 kJ/m2 in contrast to brittle pure PEF. The UV-A and blue-light shielding of nanocomposites increased from 53 % to 98 % and 28 % to 86 %, respectively, and the nanocomposites still maintained good gas barrier properties. Moreover, the antibacterial activity of nanocomposites against E. coli had increased to 98 %, better than that of the PEF/Ag NWs composites. By uniaxial pre-stretching, the tensile modulus and the elongation at break were improved obviously, from 1840 MPa to 5466 MPa and 4 % to 54 % respectively with pre-stretching ratio increasing. Compared to the PET/TiO2 NWs composites, the PEF/TiO2 NWs composites shows batter thermal property and mechanical property. The PEF/TiO2 NWs composites exhibit potential foreground in the packaging application.

Well-Designed morphology regulated ZIF-67 derived 0D/1D Co3O4@TiO2 NWs integrated with in-situ grown Ni/Co-Active metals for Low-Temperature driven CO2 methanation

Well-designed morphology regulated MOF-templated Co3O4 over titanium dioxide nanowires (TiO2 NWs) boasting intimate interfacial contact for highly efficient CO2 methanation was synthesized via a facile in-situ grown approach. The synergistic effect of 0D Co3O4 with reducible 1D TiO2 NWs and the role of Ni/Co-active metals were systematically investigated for CO2 methanation. The performance comparison of the Ni dispersed in-situ grown Co3O4 on TiO2 NWs (Insitu-10N7CT) and its mechanically assembled counterpart (M−10N7CT) was further explored. The in-situ grown ZIF-67 acts as a sacrificial template to produce Co3O4 with high dispersion of Ni active sites to enhance CH4 production. By regulating the morphology, 0D Co3O4 promoted a superior methanation performance for Insitu-10N7CT (XCO2 = 97.42 %, SCH4 = 99.29 %) compared to M−10N7CT (XCO2 = 91.45 %, SCH4 = 98.42) due to intimate interfacial contact between the Ni, Co, and Ti species. Comparatively, the MOF-derived composites displayed much higher CH4 yield than uncalcined MOF nanocomposites. This is because the high reaction temperature caused a rapid collapse of the ZIF-67 dodecahedral structure, leading to a lower methanation performance. Insitu-10N7CT exhibited higher reducibility, generating low valence oxidation/metallic states of Ni-Co-Ti, leading to the high density of oxygen vacancies (Ov). An optimal reaction temperature of 350 °C and gas hourly space velocity of 9,400 mL gcat-1h−1 was revealed, suggesting an efficient reactant contact and CO2 conversion into CH4. The Insitu-10N7CT composite exhibited durability up to 100-hour time-on-stream due to the gradual reduction of Co3O4. Thus, the novel MOF-templated ternary nanocomposite revealed a facile method for regulating the structure of MOF derivatives while boosting strong interfacial interactions for efficient renewable fuel production.

Reduced graphene oxide supported Ag-loaded brookite TiO2 nanowires: Enhanced photocatalytic degradation performance and electrochemical energy storage applications

Here, silver (Ag) nanoparticle-loaded brookite titanium dioxide (TiO2) nanowires supported on reduced graphene oxide (rGO) were successfully produced by a facile, one-step hydrothermal technique. The properties of fabricated nanowires were analyzed using XRD, FESEM, TEM, HRTEM, XPS, FTIR, Raman, UV–Vis and PL spectroscopy. SEM and TEM results indicated the nanodimensional structure of all samples. Photocatalytic performance of as-obtained Ag-TiO2/rGO nanohybrid exhibited an excellent photocatalytic performance in comparison with pure TiO2 NWs and Ag-TiO2 composite as evaluated through photocatalytic degradation of methylene blue under visible light illumination. The electrochemical properties of pure TiO2 nanowires, and Ag NPs loaded TiO2 NWs composite, and the ternary Ag-TiO2/rGO nanohybrid were investigated through cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance measurements and analysis. The present findings recommend that ternary Ag-TiO2/rGO nanohybrid provides a promising direction for the development of high quality, effective and reliable photocatalytic and electrode material for organic dyes degradation and hybrid supercapacitors respectively.

The Effect of Titania Additives on the Performance of PEO-Based Solid Sodium Batteries: Bulk and Interfacial Aspects

Nanometric fillers are known to affect the electrochemical performance of polymer electrolytes. Here, nanowires and nanotubes of TiO2 with the same crystal structure are compared as additives to poly(ethylene oxide) based electrolytes for solid state sodium batteries. Electrochemical studies of symmetric cells with blocking and non-blocking electrodes examined the effects of the additive shapes on the bulk electrolyte and Na-electrolyte interface. Impedance spectroscopy was used as a major electroanalytical tool. To obtain a full perspective, all-solid-state batteries were evaluated. In galvanostatic measurements the filler shape effect is most noticeable at a high current density. TiO2 nanotubes improve the solid electrolyte behavior considerably more than titania nanowires. This effect is related mainly to the interface of the polymeric matrix with the electrodes.

Formation of TiO2 nanowires and BNNPs using in situ hydrothermal reaction to improve thermal conductivity of cellulose

Constructing an efficient heat pathway is of utmost importance for improving the thermal conductivity of polymer-based composites. Three-dimensional (3D) filler structures can be excellently utilized to prepare thermally conductive pathways in polymer composites. A composite consisting of titanium dioxide nanowires (TiO2 NWs), boron nitride nanoparticles (BNNPs), and cellulose nanofibers (CNFs) was fabricated using a hydrothermal process, focusing on the formation of TiO2 NWs and BNNPs. After the formation of the heat transfer path, the fabricated composite with a 50 wt% filler content exhibited a 450% increase in thermal conductivity compared to raw CNF, surpassing the composites prepared via random dispersion methods. Therefore, this paper presents a promising strategy for significantly enhancing the thermal properties of the composites.

Thickness-Controllable Electrode of Lithium Titanium Oxide Nanowire Sheets with Multiple Stacked Morphology for Ultrahigh Areal Capacity and Stability of Lithium-Ion Batteries

Thickness-Controllable Electrode of Lithium Titanium Oxide Nanowire Sheets with Multiple Stacked Morphology for Ultrahigh Areal Capacity and Stability of Lithium-Ion Batteries

Highly Efficient Visible-Blind Ultraviolet Photodetector Based on Scalably Produced Titanium Dioxide Nanowire Arrays.

Here, we report a novel, feasible, and cost-effective method for the preparation of one-dimensional TiO2 nanowire arrays using a super-aligned carbon nanotube film as a template. Pure-anatase-phase TiO2 nanowires were scalably prepared in a suspended manner, and a high-performance ultraviolet (UV) photodetector was realized on a flexible substrate. The large surface area and one-dimensional nanostructure of the TiO2 nanowire array led to a high detectivity (1.35 × 1016 Jones) and an ultrahigh photo gain (2.6 × 104), respectively. A high photoresponsivity of 7.7 × 103 A/W was achieved under 7 μW/cm2 UV (λ = 365 nm) illumination at a 10 V bias voltage, which is much higher than those of commercial UV photodetectors. Additionally, by taking advantage of its anisotropic geometry, we found the TiO2 nanowire array showed polarized photodetection. The concept of using nanomaterial systems shows the potential for realization of nanostructured photodetectors for practical applications.

TiO2 nanowire formation and GO reduction through a hydrothermal reaction to improve the thermal conductivity of epoxy composites

AbstractThe thermal path must be properly configured to improve the thermal properties of polymer composites. Three‐dimensional (3D) thermally conductive networks can be used as an excellent means for building high‐speed conductive pathways in polymer composites. Titanium dioxide (TiO2) nanowire (NW)/reduced graphene oxide (rGO)/epoxy (EP) composite material has a 3D foam structure and focuses on TiO2 NW formation and rGO gelation through a hydrothermal process. The thermal conductivity of the synthetic composite material through filler loading at 50 wt.% and heat transfer path formation was 805% higher than that of pure EP, and the thermal conductivity was superior to that of the composite material with randomly dispersed fillers. Therefore, this work describes an advanced process to improve the thermal conductivity of polymer composites significantly.

Dielectric and mechanical properties of TiO2/polyimide composites with low dielectric constant

AbstractWith the advent of 5G era, the high millimeter‐wave frequency band, poor signal penetration and large loss make 5G communication more dependent on low dielectric constant materials. Therefore, the research and development of low dielectric polymer materials has become a hot spot in recent years. With its good chemical corrosion resistance, thermal stability, high dispersion and high mobility, titanium dioxide (TiO2) as a high function fine inorganic material is doped in polymer systems to improve the electrical properties of polymer composites. In recent years, a large number of studies have used spherical TiO2 nanoparticles doped on the polymer matrix, however, there is almost no research on doping nanolinear TiO2 nanoparticles on the polymer matrix. Here, TiO2 nanowires were prepared by hydrothermal method, and the prepared TiO2 nanowires were added to polyimide (PI). TiO2/PI monolayer and three‐layer composite films with good dielectric and mechanical properties were prepared by in‐situ polymerization. Fourier transform infrared spectoscopy, scanning electron microscopy and X‐ray diffraction were used to characterize the structure and test the properties of the composites. During the initiation process, the thermal initiation reaction of the composite membrane was completed. The composite film with good mechanical properties and excellent dielectric properties were obtained by adding titanium oxide nanowires, which can meet the requirements of its use in the field of microelectronic devices.