Bi2Te3 Nanorods Research Articles

Strategic rationalization for improved photocatalytic decomposition of toxic pollutants: Immobilizing Bi2Te3 nanorods and V2O5 nanoparticles over MoS2 nanosheets

Researchers have become increasingly interested in solar energy based on semiconductor photocatalysts to remove hazardous pollutants and clean the environment. In this work, an efficient MoS2-Bi2Te3-V2O5 nanocomposite has been prepared through wet impregnation method. MoS2-Bi2Te3-V2O5 photocatalyst was utilized to decompose the MB and Rh B dyes. The photocatalytic efficiency (Rh B) of MoS2-Bi2Te3-V2O5 nanocomposite (95.19 %) was higher than 2.70 times of Bi2Te3 nanorods, 1.55 times of V2O5 nanoparticles, 1.68 times of MoS2 nanosheets, 1.50 times of MoS2-Bi2Te3, and 1.21 times of MoS2-V2O5 nanocomposite, respectively. Recycling tests conducted on the MoS2-Bi2Te3-V2O5 nanocomposite revealed its high stability and durability. The outcomes obtained from the scavenger test suggest that the photogenerated hydroxyl radicals play a chief role in the photocatalytic performance of Rh B dye in the MoS2-Bi2Te3-V2O5 nanocomposite, respectively. The enhanced photocatalytic performance of the MoS2-Bi2Te3-V2O5 nanocomposite is ascribed to the strong hybrid formation of Bi2Te3, V2O5, and MoS2 nanosheets, respectively. Consequently, the straightforward and readily synthesized MoS2-Bi2Te3-V2O5 nanocomposite can serve as an economical, highly effective material for environmental applications.

Fascinating Electrical Transport Behavior of Topological Insulator Bi2 Te3 Nanorods: Toward Electrically Responsive Smart Materials.

Electrical conductivity and dielectric parameters are general inherent features of materials. Controlling these characteristics through applied bias will add a new dimension to regulate the dynamic response of smart materials. Here, a fascinating electrical transport behavior is observed in topological insulator (TI) Bi2 Te3 nanorods, which will play a vital role in intelligent materials or devices as a unit for information reception, processing or feedback. The Bi2 Te3 nanorod aggregates exhibit a monotonic resistance response to voltage, with observed four-fold change of electrical conductivity in a small range electric field of 1Vmm-1 . The dielectric constant and dielectric loss of Bi2 Te3 nanorod composites also show strong dependences on bias voltage due to the unique electrical transport characteristics. The unique voltage-controlled electrical responses are attributed to the change of Fermi levels within the band structure of disordered TInanorods, which are non-parallel to the applied electric field. The excellent controllable inherent characteristics through electric field endows Bi2 Te3 nanomaterials bright prospects for applications in smart devices and resistive random access memories.

A one-step solvothermal synthesis of the topological insulator Bi2Te3 nanorod-modified TiO2 photocatalyst for enhanced H2-evolution activity

Topological insulator Bi2Te3 nanorods as effective cocatalysts were modified on a TiO2 surface by an EG-assisted solvothermal method to improve the photocatalytic H2-evolution activity of TiO2 due to their high conductivity and suitable Te–H bond.

Enhanced thermoelectric performance of solution-grown Bi2Te3 nanorods

The dominant role of trioctylphosphine (TOP) on the precise crystallite size and enhanced thermoelectric (TE) performance of the solution-grown Bi2Te3 nanorods annealed at 250 °C for 5 h under Ar gas flow and pelletization under 1 GPa pressure at 27 °C only has been demonstrated here. This has resulted in systematic reduction of crystallite size (D), emergence of a secondary phase BiTe with increasing TOP, and enhancement in thermopower but drastic drop in thermal conductivity due to atomic-scale control over the grain size and boundaries. The highest ZT and power factor (PF) obtained for nanorods with D = 40 nm are 1.95 and 1.4 times higher than those of D = 63 nm are due to the optimum intergrain energy barrier height for filtering of the charge/heat carriers. Remarkably, this enhanced ZT/PF is promisingly greater than those of the other more sophisticatedly solution-processed samples reported earlier. Moreover, the IR-active A1u modes in Raman spectra of nanorods of centrosymmetric Bi2Te3 have been observed for the first time with TOP-induced reduction of D confirming the breaking of crystal inversion symmetry due to the formation of sub-quintuples. Thus, this grain size alteration strategy for ZT improvement will open a new vista for further development of Bi2Te3-based efficient TE materials near room temperature.

Electrochemical reaction mechanism for Bi2Te3-based anode material in highly durable all solid-state lithium-ion batteries

The electrochemical reaction mechanism of Bi2Te3 as negative electrode in all solid-state Li-ion battery (LIB) having LiBH4 as a solid electrolyte is established herein. To observe the effect of nanosized electrode material on the battery performance, Bi2Te3 nanorods were also used as anode material similar to the above battery setup. The galvanostatic discharge/charge profile suggested the first discharge and charge capacities as 533 mAhg−1 and 288 mAhg−1 for bulk Bi2Te3, which reduced to 219 mAhg−1 and 218 mAhg−1 , respectively, after 50 cycles. In case of nanorods, the first discharge and charge capacity were observed to be 489 mAhg−1 and 281 mAhg−1 , respectively, which reduced to 235 mAhg−1 and 233 mAhg−1 , respectively, after 50 cycles. The mechanism of lithiation/delithiation of Bi2Te3, as well as better performance of Bi2Te3 nanorods over its bulk counterpart, has been proposed herein.

Tuning of the Thermoelectric Properties of Bi2Te3 Nanorods Using Helium Ion Irradiation.

The present study reports an enhancement of the power factor of Bi2Te3 nanorods NRs) by helium (He+) ion irradiation. High-resolution transmission electron microscopy studies revealed the formation of amorphous layers on the surface of the NRs at the high ion fluence. This amorphous nature is due to the accumulation of migrating point defect clusters at the surface of the NRs. Raman scattering experiments provide further insight to the observed structural modifications. At higher ion fluence, impurity-dominated scattering processes significantly enhance the value of the Seebeck coefficient of Bi2Te3 NRs. The He+ ion irradiation up to the ion fluence of 1 × 1016 ions/cm2 improves the thermoelectric transport properties with the highest power factor, 8.2 μW/m K2, at 390 K. Further investigations may result in the possibility of fabricating the Bi2Te3 NRs as thermoelectric generators with a high power factor for space applications.

Hierarchical Bi2 Te3 Nanostrings: Green Synthesis and Their Thermoelectric Properties.

Bi2 Te3 hierarchical nanostrings have been synthesized through a solvothermal approach with the assistance of sucrose. The hierarchical Bi2 Te3 was supposed to be fabricated through a self-assembly process. Te nanorods first emerge with the reduction of TeO32- followed by heterogeneous nucleation of Bi2 Te3 nanoplates on the surface and tips of Te nanorods. Te nanorods further transform into Bi2 Te3 nanorods simultaneously with the nanoplates' growth leading to a hierarchical structure. By controlling the reaction kinetics by adding different amount of ethylene glycol, the length of nanorods and the number of nanoplates could be tailored. The use of sucrose is vital to the formation of hierarchical structure because it not only serves as a template for the well-defined growth of Te nanorods but also promotes the heterogeneous nucleation of Bi2 Te3 in the self-assembly process. The Bi2 Te3 nanomaterial shows a moderate thermoelectric performance because of its hierarchical structure. This study shows a promising way to synthesize Bi2 Te3 -based nanostructures through environmental friendly approach.

Morphological investigations on the growth of defect-rich Bi2Te3 nanorods and their thermoelectric properties

Bi2Te3 nanorods (NRs) have been successfully synthesized at different reaction temperatures via a surfactant-assisted hydrothermal method.

Bi2Te3 Nanorods: Preparation, Reaction Mechanism and Electrochemical Property

A rapid chemical method has been developed for the synthesis of the Bi2Te3 nanorods with hexagonal crystalline phase. The method is based on the template-engaged synthesis in which the Te nanowires were used as template reagents. On the basis of a series of experiments and characterizations, the effect factors and the formation mechanism of the Bi2Te3 nanorods were discussed. Furthermore, the electrochemical property of the Bi2Te3 nanorods was determined by the voltammetric technique.

Controllable Synthesis of Bismuth Chalcogenide Core–shell Nanorods

Bi2S3/Bi and Bi2Te3/Bi core–shell nanorods were successfully synthesized by a hydrothermal method using Bi2S3 nanorods as the template. The thickness of the Bi shell was controlled by varying the reaction time or the Bi2S3-to-Te ratio. Phase-pure Bi and Bi2Te3 nanorods were also obtained by this synthetic approach. The formation of Bi2S3/Bi and Bi2Te3/Bi core–shell nanorods can be separated into two different processes. One is the reduction of Bi2S3 nanorods by hydrazine. The other is the formation of Bi2Te3 through the exchange of Te2– and S2– and the subsequent reaction of Bi with Te. The formation mechanisms for the core–shell nanorods are discussed in detail.

Facile synthesis and thermoelectric studies of n-type bismuth telluride nanorods with cathodic stripping Te electrode

Bismuth telluride (Bi2Te3) nanorods (NRs) of n-type thermoelectric materials were prepared using an electrogenerated precursor of tellurium electrode in the presence of Bi3+ and mercapto protecting agent in aqueous solution under atmosphere condition. The optimal preparation conditions were obtained with ratio of Bi3+ to mercapto group and Te coulomb by photoluminescence spectra. The mechanism for generation of Bi2Te3 precursor was investigated via the cyclic voltammetry. The highly crystalline rhombohedral structure of as-prepared Bi2Te3 NRs with the shell of Bi2S3 was evaluated with high resolution transmission electron microscopy (HRTEM) and powder X-ray diffraction (XRD) spectroscopy. The near-infrared absorption of synthetic Bi2Te3 NRs was characterized with spectrophotometer to obtain information of electron at interband transition. The thermoelectric performance of Bi2Te3 NRs was assessed with the result of electrical resistivity, Seebeck coefficient, thermal conductivity, and the figure of merit ZT parameters, indicating that thermoelectric performance of as-prepared Bi2Te3 nanocrystals was improved by reducing thermal conductivity while maintaining the power factor.

Synthesis, characterization and enhanced thermoelectric performance of structurally ordered cable-like novel polyaniline–bismuth telluride nanocomposite

Bismuth telluride (Bi2Te3) nanorods and polyaniline (PANI) nanoparticles have been synthesized by employing solvothermal and chemical oxidative processes, respectively. Nanocomposites, comprising structurally ordered PANI preferentially grown along the surface of a Bi2Te3 nanorods template, are synthesized using in situ polymerization. X-ray powder diffraction, UV–vis and Raman spectral analysis confirm the highly ordered chain structure of PANI on Bi2Te3 nanorods, leading to a higher extent of doping, higher chain mobility and enhancement of the thermoelectric performance. Above 380 K, the PANI–Bi2Te3 nanocomposite with a core–shell/cable-like structure exhibits a higher thermoelectric power factor than either pure PANI or Bi2Te3. At room temperature the thermal conductivity of the composite is lower than that of its pure constituents, due to selective phonon scattering by the nanointerfaces designed in the PANI–Bi2Te3 nanocable structures. The figure of merit of the nanocomposite at room temperature is comparable to the values reported in the literature for bulk polymer-based composite thermoelectric materials.

Facile synthesis of ultra-small Bi2Te3 nanoparticles, nanorods and nanoplates and their morphology-dependent Raman spectroscopy

High-crystalline 0D, 1D and 2D ultra-small Bi2Te3 nanocrystals were synthesized using the pyrolysis of organometallic compound method. The Bi2Te3 nanocrystals was studied with transmission electron microscopy (TEM). Samples synthesized at 35°C possessed a dominant morphology of 0D nanoparticles or 1D nanorods, while samples synthesized at temperatures higher than 75°C possessed a dominant morphology of 2D nanoplates. Phonon vibrations were investigated by Raman spectroscopy. The 2D nanoplates showed similar Raman features as few-quintuple-thick Bi2Te3 layers, while the 0D and 1D nanostructures showed a blue-shifted A1g2 mode and a much stronger A1u mode. This is the first report regarding the morphology effect on the Raman-active phonon modes of Bi2Te3 nanocrystals.

Temperature-dependent thermal conductivity of nanorod-based nanofluids

In this work, the temperature dependence of thermal conductivity enhancement in nanofluids containing Bi2Te3 nanorods has been studied. The Bi2Te3 nanorods of average diameter 20nm and length 170nm are synthesized using the sonochemical technique. The 3ω-wire method has been developed to measure the thermal conductivity of nanofluids. The thermal conductivity enhancement in the nanorods-in-FC72 and the nanorods-in-oil nanofluids has been experimentally found to decrease with increasing temperature, in contrast to the trend observed in nanofluids containing spherical nanoparticles. The contrary trend is attributable mainly to the particle aspect ratio.

Synthesis and Characterization of Bismuth Sulfide and Bismuth Telluride Nanorods and their Polyaniline Nanocomposites

We present here a simplified approach to the synthesis of bismuth sulfide and bismuth telluride nanorods and their polyaniline(PAN)-coated nanocomposites. The present method gives highly crystalline nanorods of bismuth sulfide of varying aspect ratio depending on the capping ligand employed, and involves reacting bismuth(III) trioleate with thioacetamide in phenyl ether at elevated temperatures in the presence of excess capping ligand. Bismuth telluride was obtained in high yields by reacting bismuth(III) trioleate with trioctylphosphine telluride at relatively low temperature. Oleic acid, sodium dodecylsulfonate and sodium dodecylbenzene sulfonate, used as capping ligands, did not have significant effect on the aspect ratio of Bi2Te3 nanorods. The nanostructured materials obtained this way were then coated with polyaniline (PAN) by heating a specific amount of material with half as much PAN in toluene close to reflux temperature for 6–8 h. It was necessary to keep the mixture thoroughly stirred and intermittently sonicated in order to ensure that the particles remain dispersed at all times. Bismuth chalcogenide nanoparticles as well as their composites were characterized using transmission electron microscopy and X-ray powder diffraction.