Titanate Nanowires Research Articles

Enhanced piezoelectric response in BTO NWs-PVDF composite through tuning of polar phase content

We have fabricated a flexible, environment friendly piezoelectric nanogenerator (PENG) based on the ferroelectric Polyvinylidene fluoride (PVDF) composite incorporated with Barium titanate (BaTiO3) nanowires (NWs) of piezoelectric coefficient d 33 = 308 pm V−1. The single-layered PENG can deliver output power density of 10 μW cm−2 and an output voltage of 2 V with a nominal mechanical load of 1 kPa. BaTiO3 (BTO) NWs of different concentrations were incorporated into PVDF to tune the polar phase content, internal resistance, and optimize the output power. We show that there exists a critical value of BTO NWs loading of 15 wt%, beyond which the piezoelectric energy harvesting characteristics of the PVDF nanocomposites decrease. The oxygen vacancies present in the BTO NWs surface attract the fluorine ions of PVDF chain and favour the formation of β phase. The enhanced value of dielectric constant and dielectric loss of BTO-PVDF samples in the low frequency region suggest strong interfacial polarization in the composite system. The fabricated PENG can charge a super-capacitor up to 4 V within 35 s. The origin of the high power output from the BTO (15 wt%)-PVDF composite is attributed to the combined effect of enhanced polar phase content, strong interfacial polarization, and reduced internal resistance. This study provides an effective pathway in enhancing the performance of BTO-PVDF based piezoelectric energy harvesters.

Fabrication of Barium Titanate Nanowires-GNP Composite Bilayer Photoanodes for the High-Performance Dye-Sensitized Solar Cells

Inorganic perovskite barium titanate nanowires (BTNWs) and their nanocomposites comprised of different weight percentages (1, 2, and 3 wt%) of graphene nanoplatelets (GNP) are synthesized via a hydrothermal method and used as photoanode materials of dye-sensitized solar cells (DSSCs). Morphological analysis of the BTNWs and BTNWs + GNP composites has indicated that the one-dimensional BTNWs and two-dimensional GNP are formed as uniformly distributed, well-connected mesoporous microstructures. UV–visible absorption and Raman studies of the BTNWs + GNP composites have revealed a narrowing bandgap, improved visible light absorption with increasing GNP content, and a superior light-scattering effect of BTNWs. Besides, four different DSSC bilayer photoanodes comprising titanium dioxide nanoparticles (TNP) underlayer and an upper layer with BTNWs + (0, 1, 2, and 3 wt%) GNP composites are fabricated to elucidate the TNP + BTNWs and BTNWs + GNP composite sublayer(s) influences on the photovoltaic performance. The TNP + BTNWs + 2 wt% GNP composite bilayer photoanode has demonstrated a higher power conversion efficiency of 9.92 % as compared to that of the other TNP + BTNWs + GNP composite bilayer photoanodes in DSSCs, due to the higher charge recombination resistance, faster charge transport, superior charge collection ability and carrier lifetime of its sublayers.

Sodium titanate nanowires for Na+‐based hybrid energy storage with high power density

AbstractIt is crucial to enhance the rate capability of the titanium‐based materials for fulfilling their promising potential as the anode materials of sodium‐ion batteries (SIBs). Herein, Mn‐doped sodium titanate (Mn‐NTO) nanowires with homogeneously distributed ultrathin carbon nanosheets (Mn‐NTO@C) are synthesized by a one‐step salt‐template‐assisted method, showing much‐enhanced power density. The as‐prepared Mn‐NTO@C demonstrates the realization of hybrid energy storage, which reconciles the diffusion‐controlled behavior with the pseudocapacitive‐controlled behavior. It has been revealed that the Mn heteroatoms can raise the proportion of Na2Ti3O7 phase with the expanded crystal lattice, facilitating the diffusion‐controlled insertion/extraction process of sodium ions. Meanwhile, the hybrid morphology of Mn‐NTO nanowires and carbon nanosheets provides a promoted structure stability. As a result, the assembled Na||Mn‐NTO@C half‐cells work well at an extreme current density of 24 A g−1 for 10 000 cycles with a capacity retention of 95.2%. Moreover, the Mn‐NTO@C||Na3V2(PO4)3 (NVP) full cells exhibit an attenuation of only 0.0015% per cycle at 20 A g−1 for over 10 000 cycles, and the energy density and power density of the full cells reach an ultrahigh level of 262 Wh kg−1 and 16.3 kW kg−1, respectively.

Synergistically enhancing cycleability and rate performance of sodium titanate nanowire anode via hydrogenation and carbon coating for advanced sodium ion batteries

Synergistically enhancing cycleability and rate performance of sodium titanate nanowire anode via hydrogenation and carbon coating for advanced sodium ion batteries

The effect of Mn-doping on dielectric properties of titanate nanowires

Mn-doped titanate nanowires (TNWs) with system of MnxTi3-xO7 (Na0.96H1.04∙3.42H2O) (where x = 0, 0.05, 0.10, 0.20, and 0.30) were fabricated a hydrothermal route at 130 °C for 24 h. The products were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-vis spectroscopy. The nanowires were an average diameter of about 10–50 nm and an average range length of micrometer scales. The dielectric relaxation in the MnxTi3-xO7 (Na0.96H1.04∙3.42H2O) system was determined by LCR Meter in difference frequency (102–106 Hz) at various temperatures. The Mn-doped TNWs samples showed a giant dielectric exhibit with a dielectric constant of about 104 at 30 °C and 1 kHz. They all have a Debye-like relaxation based on the Maxwell-Wagner polarization. The dielectric constant of Mn-doped TNWs significantly increased with increasing doping levels.

Lead titanate nanowires/polyamide-imide piezoelectric nanocomposites for high-temperature energy harvesting

With an increasing demand for self-powered microelectronics to be used in scientific tasks and exploration missions in extreme environments, the implementation of piezoelectric energy harvesting at high temperature is an important research focus for renewable energy sources. Piezoelectric composites made from piezoelectric ceramic fillers and polymer matrices combine high electromechanical coupling with flexibility, resulting in a versatile candidate for energy harvesting. In this research, a nanocomposite formed by lead titanate nanowires (PbTiO3 NWs) and a polyamide-imide (PAI) matrix is developed and shown to have an excellent piezoelectric response at high temperatures. By in situ measurements of the piezoelectric g31 and d31 coefficients of the nanocomposite films with different PbTiO3 NW weight fractions in the temperature range 25–250 °C, the dependence of temperature and filler concentration on the piezoelectric properties are fully characterized. In addition, the effect of NW alignment on piezoelectric properties through direct ink writing is also studied. Finally, a bending-mode energy harvester made from this nanocomposite is demonstrated to generate a maximum power density of 33 μW·m−2 at resonance and a power density of 20 μW·m−2 under low-frequency random excitation at 200 °C, while keeping a long operating life of at least 100 h. In conclusion, this work provides a new solution for high-temperature energy harvesting from low-frequency random vibrations using PbTiO3/PAI nanocomposites.

Transition-metal doped titanate nanowire photocatalysts boosted by selective ion-exchange induced defect engineering

Defect engineering through elemental doping is an efficient way to boost the performance of semiconductor photocatalysts. Herein, transition-metal (TM) doped titanate nanowires (TNWs) were prepared via ion-exchange over the titanate precursors and demonstrated for the Rhodamine B (RhB) degradation under ultraviolet (UV) light irradiation. The ion-exchange of selective ions (V5+, Cr3+, Ni2+, and Zn2+) with protons from pristine TNWs resulted in the hierarchical meso-porosity of nanowires with large pores of ∼5–20 nm by TM doping and small pores of ∼3.6–4.5 nm inherited from pristine TNWs, which facilitates the mass transfer while maintaining high surface area and active sites. Meanwhile, the TM intercalation partially reduces the Ti4+ to Ti3+ and narrows the optical bandgap, which, together with oxygen vacancies and superoxide radicals from pristine TNWs, enhance the adsorption and photocatalytic degradation performance of RhB. This work helps to elucidate the effects of transition-metal doping and provides a rational strategy towards high performance titanate-based photocatalysts for efficient and sustainable wastewater treatment.

Novel lead-free BCZT-based ceramic with thermally-stable recovered energy density and increased energy storage efficiency

The eco-responsible lead-free piezoelectric ceramics have been intensively searched for more than a decade, however, the final goal to replace toxic ceramics like lead zirconate titanate (PZT) with lead-free compounds, having comparable or even better performance has not yet been reached. In this road, the lead-free ceramics Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT), possessing excellent dielectric, ferroelectric, and piezoelectric properties are regarded as serious candidates for the PZT replacement. Besides, nanostructuring BCZT is of paramount importance to enhance these functionalities even more. Here, BCZT multipodes are designed by template-growth hydrothermal synthesis using hydrogen zirconate titanate nanowires. We demonstrate that the fabricated BCZT multipodes exhibit high dielectric permittivity of 5300 with a temperature stability coefficient of ±5.9% between 20 and 140 °C. A significant recovered energy density of 315.0 mJ/cm3 with high thermal stability and high energy storage efficiency of 87.4%, and enhanced large-signal piezoelectric coefficient d33∗ (310 pm/V) are found. Compared to the traditional BCZT ceramics reported in the literature, relying on high-temperature processing, our sample exhibits boosted energy storage parameters at a much lower temperature. These outcomes may offer a new strategy to tailor eco-responsible relaxor ferroelectrics toward superior energy storage performance for ceramic capacitor applications.

Modulation of titania nanoflower arrays transformed from titanate nanowire arrays to boost photocatalytic Cr(vi) detoxification

The integration of the N/S co-doping, anatase/rutile junction construction, and morphology regulation of TiO2 arrays is achieved by a simple method to improve photocatalytic activity.

Surface-Functionalization of Hydrogen Titanate Nanowires for Highly Selective Adsorption and Separation of Methylene Blue

Surface-Functionalization of Hydrogen Titanate Nanowires for Highly Selective Adsorption and Separation of Methylene Blue

Bi-Functional Co, Fe (Co)Doped Titanate Nanowires for Photo-Assisted Oxidation of Emergent Pollutants

Bi-Functional Co, Fe (Co)Doped Titanate Nanowires for Photo-Assisted Oxidation of Emergent Pollutants

Trigger Na+-solvent co-intercalation to achieve high-performance sodium-ion batteries at subzero temperature

Due to the sluggish interfacial kinetics, the energy density and cycle life of sodium-ion batteries (SIBs) suffer severely at subzero temperatures. Herein, to accelerate the interfacial charge transfer process and improve the low-temperature SIBs performance, a strategy by triggering Na+-solvent co-intercalation is proposed. Using hydrogen titanate nanowires (HT-NW) as a model, we found that the layer structure regulation with oxygen defects could trigger HT-NW presents a unique Na+-solvent co-intercalation behavior in the ether-based electrolyte at −25 °C according to ex-situ FTIR and XRD. By eliminating the Na+ desolvation process, Na+-solvent co-intercalation could effectively accelerate the Na+ diffusion kinetics and reduce the activation energy to 66.0 meV. Benefit from these ameliorations, the defective HT-NW delivers a high capacity of 238 mAh g−1 at −25 °C, which is equivalent to 89% of that at 25 °C. Besides, the defective HT-NW shows great superiority in cycle stability, maintaining capacity retention of 80.6% after 4200 cycles at 1.0 A g−1 at −25 °C. Moreover, at −25 °C, the defective HT-NW//Na3V2(PO4)3 full cell exhibits high energy density (119.1 Wh kg−1) and outstanding stability (94.5% after 1000 cycles at 1.0C). These findings reveal that the ion–solvent co-intercalation is highly feasible to improve the battery performance at low temperatures by accelerating charge transfer kinetics.

Deposition of ultrasmall γ-Mo2N nanocrystals on TiO2 nanowires and their promotion effect on photocatalytic activity

Mo2N decorated TiO2 nanowires were obtained via impregnating titanate nanowires with a mixture of (NH4)6Mo7O24 and hexamethylenetetramine, followed by the calcination at 600–800 oC in N2 atmosphere. The results show that only Mo6+ species can be found in the sample calcined at 600 oC while Mo element is still dominantly in the form of Mo6+ with a negligible amount of γ-Mo2N (namely Moδ+, 0 ​< ​δ ​< ​4) and Mo4+ at 700 oC. In the sample calcined at 800 oC, however, ultrasmall γ-Mo2N nanocrystals with an average size of about 3.3 ​nm can be observed on the surface of TiO2 nanowires. The photocatalytic activity test reveals that, although the γ-Mo2N-absent sample obtained at 800 oC is dominantly in the form of inert rutile TiO2, the introduction of γ-Mo2N nanocrystals can significantly improve its performance to be more than doubled in methyl orange (MO) removal percentage, increasing from 36.5% to 75.5% after 2h irradiation (high-pressure mercury lamp), due to the formation of heterojunction between γ-Mo2N and TiO2 nanowires. Furthermore, 5% γ-Mo2N decorated TiO2 exhibit better photocatalytic activity due to its higher surface area and more heterojunctions between γ-Mo2N and TiO2. This γ-Mo2N decorated TiO2 photocatalyst can broaden the practical scope of rutile TiO2 and have a promising potential in photocatalytic application.

Chitosan modified inorganic nanowires membranes for ultra-fast and efficient removal of Congo red

Chitosan modified hydrogen titanate nanowires membrane is prepared through a simple immersion-filtration method, which can be used to adsorb anionic dyes. The adsorption kinetics data shows that the adsorption process follows the pseudo-second-order model. Thermodynamics analysis reveals the adsorption is a spontaneous process. During the dynamic adsorption process, chitosan modified hydrogen titanate nanowires membrane shows excellent removal rate of 99.5% and adsorption capacity of 374.4 mg g−1 for Congo red. The membrane exhibits excellent cyclic adsorption performance and satisfactory removal rate in the pH range of 2.5–12.5. After 15 adsorption–desorption cycles, the removal rate and permeability of Congo red remain above 98.7% and 1120.0 L m-2h−1 bar−1, respectively.

Barium titanate nanorods on micro-machined silicon substrate for performance enhancement of piezoelectric Nanogenerators (NGs)

Today, barium titanate nanowires as a piezoelectric material can transmit more energy and generate energy during energy harvesting. The silicon substrate is of great importance in some respects, especially the issue of integration and a hybrid nanogenerator based on BaTiO3 NRs/PDMS composite film on silicon substrate is introduced. Here, FTO layer is used both as seed layer for the TiO2 NRs and as bottom electrode by pyrolysis spray method. The growth of BaTiO3 NRs consists of two hydrothermal stages: the first is growing the TiO2 nanorods and the second is the conversion of TiO2 to BaTiO3 (BTO). To increase the output voltage of the nanogenerator (NG), the surface roughness of silicon substrate is investigated. The results show that the peak-to-peak voltage of the NG output, which is made on a micro-machined substrate with the pattern of micro-digits at a height of 20 μm, compared to the smooth substrate is 1.92–1.48 V in frequency of 20 Hz. which is a 30% increase and the piezoelectric coefficient of the grown BTO is around 200 pC/N.

Electron Beam Modulated Wettability and Electrical Conductivity of Hydrogen Titanate Nanowires

Electron Beam Modulated Wettability and Electrical Conductivity of Hydrogen Titanate Nanowires

Facile synthesis of dual-phase lithium titanate nanowires as anode materials for lithium-ion battery

A facile method to synthesize dual phase Li4Ti5O12-TiO2 nanowires and their performance as anode material for lithium-ion battery are investigated. Li4Ti5O12-TiO2 nanowires are obtained from titanium nanoparticles by applying the wet corrosion process for the nanostructure formation and subsequent ion exchange processes. Post-heat treatments are adopted to tune the mixed phase composition of the nanowires, which significantly influences the electrochemical performance. The dual phase nanowires-based anode materials with a TiO2: Li4Ti5O12 phase ratio of 7:3 exhibit the highest delithiation capacity of 180 mAh/g and 105 mAh/g at 0.5 C and 5 C, respectively. In addition, it shows a remarkable capacity retention of ~95% after 150 cycles at 5 C, which is a significant improvement compared to previous reports on Li4Ti5O12-TiO2 based anode materials synthesized at low temperatures. This dual phase anode material based on Li4Ti5O12-TiO2 nanowires combines two advantages: i) High aspect ratio nanostructures increase the surface area and shorten the diffusion path of lithium ions and ii) the dual phase accelerates ion/electron migration owing to abundant interfaces/grain boundaries. Consequently, the proposed synthesis route for Li4Ti5O12-TiO2 nanowires provides an effective and highly reproducible approach to fabricate dual phase Li4Ti5O12-TiO2 nanowires as anode materials for lithium ion batteries.

Ion beam joining of ceramic and carbon-based nanostructures

Ion beam assisted joining of nanostructured materials is a relatively new field. In particular, ion beam technique has been proven to be worthwhile for joining ceramic nanostructures. However, a large scope is still remaining to study heterojunctions between two dissimilar materials as the process of formation of bonds between two dissimilar materials is still to be understood. In this work we pick up a ceramic oxide and carbon based material to study ion beam joining. Specifically, we for the first time show heterojunction formation between hydrogen titanate nanowire (HTNW) and carbon nanotube (CNT) by the low energy ion beam. In order to understand the mechanism, we have invoked density functional theory and three-dimensional ion–solid interaction simulations. Experimental results are supported by predictions of simulations and suggest that the joining is established through ion beam mixing, surface defects and sputter redeposition at the junction points. The current study enlightens how the defects and sputtered out atoms are involved in the joining process. The chemical bonds between HTNW and CNT are formed only when C vacancy and simultaneously non-lattice O and C were produced during irradiation. The effect of joining on electrical conductivity and surface wetting has also been studied experimentally in this work, which is supported by simulations.

MXene potassium titanate nanowire/sulfonated polyether ether ketone (SPEEK) hybrid composite proton exchange membrane for photocatalytic water splitting.

A cross-linked sulfonated polyether ether ketone (C-SPEEK) was incorporated with MXene/potassium titanate nanowire (MKT-NW) as a filler and applied as a proton exchange membrane for photocatalytic water splitting. The prepared hybrid composite PEM had proton conductivity of 0.0097 S cm−1 at room temperature with an ion exchange capacity of 1.88 meq g−1. The hybrid composite proton exchange membrane is a reactive membrane which was able to generate hydrogen gas under UV light irradiation. The efficiency of hydrogen gas production was 0.185066 μmol within 5 h for 12% wt of MKT-NW loading. The results indicated that the MKT-NW/C-SPEEK membrane is a promising candidate for ion exchange with hydrogen gas evolution in photocatalytic water splitting and could be applied as a renewable source of energy to use in various fields of applications.

Efficiency improving of NEMS solar cell using piezoelectric nanowires

This paper presents a new structure of solar cells based on NEMS (Nano Electro Mechanical System) technology to eliminate dependence of cell to band gap energy and improve efficiency. In this paper, the process of converting solar energy to electrical energy using NEMS solar cell, which is able to convert the thermal to mechanical energy and then to electrical energy by changing the temperature and using direct piezoelectric effect, is investigated. Thus, unlike photovoltaic cells, these cells have ability to absorb the full spectrum of the sun’s radiation. Energy conversion is such that at first a two-layer cantilever with different thermal expansion coefficient (Al aluminum and SiO2 Silicon Oxide) is diverted by solar energy absorption, thus the solar energy is converted to mechanical energy. This structure is capable to receive heat energy from all spectrum of solar radiations. The mechanical oscillation of PZT (Lead Zirconate Titanate) nanowires, which are perpendicular to cantilever beams, is converted to electrical energy. The electrical voltage produced by the proposed structure is an alternating voltage with amplitude of 0.9 volts. Also, the efficiency of this proposed cell, which was introduced at first time and does not have a similar sample, is 40% which shows improved performance and much smaller size compared to previous works.