Tellurium Nanostructures Research Articles

A Rapid Room-Temperature NO2 Sensor Based on Tellurium–SWNT Hybrid Nanostructures

One-dimensional nanostructure-based chemiresistive sensors have received great attention because of their compact design and excellent sensing performance, including high sensitivity, low detection limits, low power consumption, and the ability to integrate multisensor arrays. However, these sensors generally suffer from slow response and recovery times when they are operated at ambient conditions because of slow catalytic or absorption/desorption processes. The sensors overcome this obstacle by operating at high temperature, which increases the device complexity with a higher power consumption rate. In this work, we demonstrated the construction of an ultrafast NO2 sensor at ambient conditions by utilizing feather-like tellurium (Te) nanostructures functionalized on single-walled carbon nanotube networks. By tailoring the morphology and density of Te nanostructures, hybrid nanostructures show excellent response and recovery times of approximately 63 s and 7 min to 100 ppbV NO2 gas at room temperature.

THE EFFECT OF SUBSTRATE TEMPERATURE ON FABRICATION OF ONE-DIMENSIONAL NANOSTRUCTURES OF TELLURIUM

Tellurium nanostructures have been prepared by physical vapor deposition method in a tube furnace. The experiments were carried out under argon gas flow at a pressure of 1 mbar. Tellurium powder was evaporated by heating at 350°C and 430°C and was condensed on substrates at 110–250°C, in the downstream of argon gas flow. The products were characterized by field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). FESEM revealed that most of the products have one dimensional structure. X-Ray diffraction (XRD) patterns show that the products are crystalline with hexagonal structures.

Fabrication of CdTe/Te Hetero-Nanostructures by Vapor-Solid Process

CdTe/Te core-shell heterostructures were fabricated by the vapor phase synthesis at low temperatures using a quartz tube furnace. Two step vapor-solid processes were employed. First, various tellurium structures such as nanowires, nanorods, nanoneedles, microtubes and microrods were synthesized under different deposition conditions. These tellurium nanostructures were then used as substrates in the second step to synthesize the CdTe/Te core-shell heterostructures. Using this method, various sizes, shapes and types of CdTe/Te core-shell structures were fabricated under a range of conditions. The temperature, pressure and gas flow rate were very important parameters for synthesizing these nanostructures in the vapor phase process. The morphology, crystal structure and orientation were characterized by field-emission scanning microscopy, field-emission transmission electron microscopy and X-ray diffraction. The vapor phase process at low temperatures appears to be an efficient method for producing a variety of Cd/Te hetero-nanostructures. In addition, the hetero-nanostructures can be tailored to the needs of specific applications by deliberately controlling the synthetic parameters.

Microstructure and ordering of iron vacancies in the superconductor systemKyFexSe2as seen via transmission electron microscopy

Structural investigations by means of transmission electron microscopy (TEM) on KFexSe2 with 1.5 \leq x \leq 1.8 have revealed a rich variety of microstructure phenomena, the KFe1.5Se2 crystal often shows a superstructure modulation along the [310] zone-axis direction, this superstructure can be well interpreted by the Fe-vacancy order within the a-b plane. Increase of Fe-concentration in the KFexSe2 materials could not only result in the appearance of superconductivity but also yield clear alternations of microstructure. Structural inhomogeneity, the complex superstructures and defect structures in the superconducting KFe1.8Se2 sample have been investigated based on the high-resolution TEM.

Controlled Synthesis of Tellurium Nanostructures from Nanotubes to Nanorods and Nanowires and Their Template Applications

In the present study, we report a facile hydrothermal route developed to synthesize various 1D tellurium nanostructures including nanotubes, nanowires, and nanorods on a large scale. Te nanotubes with a tunable diameter from 200 nm to 2 μm are fabricated in NaOH solution. With poly(vinyl pyrrolidone) as the surfactant, ultrathin Te nanowires with a diameter of 5−8 nm are synthesized in NaOH solution. However, in both cases, only Te nanorods are obtained if NaOH is not added. The formation of Te nanotubes is attributed to the depletion of Te atoms at the surface of seeds. The influence of the reaction conditions including pH value, reaction temperature, reducing agent, and reactant concentration on the size and morphology of the Te nanostructures is investigated and the structural evolution with different growth rate is illustrated. A reduction reaction rate controlled growth mechanism has been proposed for the variable nanostructures. In addition, the obtained Te nanostructures are ideal templates to synthesize other Te-related nanocompounds, which is demonstrated by the synthesis of ultrathin Ag2Te nanowires through the direct reaction of ultrathin Te nanowires with AgNO3 at room temperature.

Formation of single-crystal tellurium nanowires and nanotubes via hydrothermal recrystallization and their gas sensing properties at room temperature

Single-crystal tellurium nanowires and nanotubes were selectively synthesized from tellurium powder through a hydrothermal recrystallization route. The nanowires have an average diameter of 40 nm and lengths of several micrometers, while the nanotubes have diameters of 100–200 nm and lengths of 1–2 µm. The morphologies of the as-obtained tellurium nanocrystals could be controlled by tuning the amount of hydrochloric acid added in the hydrazine hydrate solution. The experimental results demonstrated that tellurium powder could be dissolved and recrystallized in hydrazine hydrate solution under hydrothermal conditions. A dissolution–recrystallization mechanism was proposed for the conversion from tellurium powder to tellurium nanowires or nanotubes. The gas sensing properties of as-synthesized tellurium nanowires and nanotubes were investigated in detail, which revealed that the as-prepared tellurium nanowires and nanotubes, especially the tellurium nanowires, exhibited excellent sensitivity to NH3 at room temperature. The response times of the tellurium nanowires and nanotubes were 5 s and 18 s, and the recovery times were 720 s and 170 s, respectively, which are shorter than those reported for tellurium films. The as-prepared tellurium nanostructures could have potential applications in nanosensors.

Comment On “1D Tellurium Nanostructures: Photothermally Assisted Morphology‐Controlled Synthesis and Applications in Preparing Functional Nanoscale Materials”

Comment On “1D Tellurium Nanostructures: Photothermally Assisted Morphology‐Controlled Synthesis and Applications in Preparing Functional Nanoscale Materials”

Response To Comment On “1D Tellurium Nanostructures: Photothermally Assisted Morphology‐Controlled Synthesis and Applications in Preparing Functional Nanoscale Materials”

Response To Comment On “1D Tellurium Nanostructures: Photothermally Assisted Morphology‐Controlled Synthesis and Applications in Preparing Functional Nanoscale Materials”

Tellurium Nano-Structure Based NO Gas Sensor

Tellurium nanotubes were grown on bare and silver/gold nanoparticle (nucleation centers) deposited silicon substrates by vacuum deposition technique at a substrate temperature of 100 degrees C under high vacuum conditions. Silver and gold nanoparticles prepared on (111) oriented silicon substrates were found to act as nucleation centers for growth of Tellurium nanostructures. Density of nanotubes was found to increase while their diameter reduced when grown using metallic nanoparticle template. These Te nanostructures were investigated for their gas sensitivity. Tellurium nanotubes on Ag templates showed better response to NO in comparison to H2S and NH3 gases. Selectivity in response to NO was improved in comparison to Te thin film sensors reported earlier. The gas sensing mechanism was investigated using Raman and X-ray photoelectron spectroscopy techniques. The interaction of NO is seen to yield increased adsorption of oxygen that in turn increases hole density and conductivity in the material.

Construction of Unconventional Hexapod-like Tellurium Nanostructure with Morphology-Dependent Photoluminescence Property

Unconventional hexapod-like tellurium nanostructures have been successfully constructed through an easy solution-based approach by recrystallizing Te powder in a mixture of ethylenediamine and hydrazine hydrate at 110 °C for 72 h. The hexapod-like nanostructure is composed of six cross-linked branches with length of about 1 μm. Each branch consists of two perpendicularly intersected nanoribbons with a constant thickness of 12 nm and tapered width from ∼200 nm at root to less than 20 nm at tip. Prominent photoluminescence emission centered at around 428 nm in blue-violet region under excitation wavelength of 365 nm has been found to be closely associated with the unique morphology of the product. A possible solid-solution-solid mechanism has been proposed on the basis of experimental facts to elucidate the formation this unconventional nanostructure. The influence of reaction temperature and solution property on the morphology and structure of the final product has also been discussed.

Synthesis of Tellurium Nanostructures by Physical Vapor Deposition and Their Growth Mechanism

One-dimensional tellurium nanostructures have been prepared by thermal evaporation in a tubular furnace under argon gas flow at a pressure of 1 atm. The depositions were found to occur along the length of the quartz tube with microrods deposited at higher temperatures (350–400 °C) and nanotubes at lower temperatures (<200 °C). It was observed that the growth of nanostructures is initiated by nucleation of spherical particles followed by growth of one-dimensional structures. Possible mechanisms for the growth of these nanostructures and the effect of source temperature on the structures obtained are discussed.

1D Tellurium Nanostructures: Photothermally Assisted Morphology‐Controlled Synthesis and Applications in Preparing Functional Nanoscale Materials

AbstractA facile visible‐light‐assisted solution‐phase approach has been successfully developed to synthesize trigonal Te 1D nanostructures. By varying the relative amount of H2TeO3 and water‐soluble polymers, wirelike, beltlike, tubular Te, and Te nanoparticle‐joined 1D aggregates, as well as a novel thorny 1D assembly of Te nanothreads can be synthesized on a large scale. The diameter of the Te nanowires can be modulated by controlling the nucleation and growth process through modulation of the pH value of the reaction mixture. It is believed that the light irradiation and thermal effect play a significant role in this photothermally assisted technique. We have shown that the Te nanowires can be used as a template to prepare Pt–Te nanochains, where the composition of Pt in the Pt–Te 1D products can be modulated by adjusting the ratio of the Te nanowires and Pt salts. Preliminary optical investigations reveal that blue–violet emission of Te nanowires can be enhanced by the formation of defects or dislocations in the Te region through the galvanic replacement reaction between Te nanowires and H2PtCl6. In addition, we demonstrate that Te 1D nanostructures can be utilized to prepare Te at carbon‐rich nanocables and carbonaceous nanotubes. Te–Pt at carbon‐rich nanocables can also be fabricated using Te–Pt nanochains as the template. These Pt–Te nanochains and carbonaceous nanostructures are expected to find wide applications in electrochemistry, catalysis, fuel cells, sensors, and other fields. Furthermore, the successful preparation of Te 1D nanostructures with abundant shapes, Pt–Te nanochains, and their carbonaceous composite nanomaterials will offer great opportunities to explore the dependence of novel properties of nanomaterials on their morphology and composition, regulate the photoconductivity of semiconductors, and also be essential for the manufacture of potential optoelectronic devices.

High-Quality Luminescent Tellurium Nanowires of Several Nanometers in Diameter and High Aspect Ratio Synthesized by a Poly (Vinyl Pyrrolidone)-Assisted Hydrothermal Process

Large-scale selective synthesis of uniform single crystalline tellurium nanowires with a diameter of 4-9 nm, and microbelts with a width of 250-800 nm and tens of micrometers in length, can be realized by a poly (vinyl pyrrolidone) (PVP)-assisted hydrothermal process. The formation of tellurium nanowires and nanobelts in the presence of PVP is strongly dependent on the reaction conditions such as temperature, the amount of PVP, and reaction time. The results demonstrated that the keys for selective synthesis of Te nanobelts and nanowires are to modulate the growth rates of (100), (101), and (110) planes in the presence of PVP and to precisely control the reaction kinetics. High-quality luminescent ultrathin t-Te nanowires with a diameter of 4-9 nm display strong luminescent emission in the blue-violet region. This approach provides a facile route for the production of high-quality tellurium nanostructures with an interesting optical property. Furthermore, the synthesized ultrathin nanowires with deep blue color and nanobelts in gray color by this approach can be well dispersed in water or ethanol, making it possible for further engineering of their surfaces to prepare other hybrid core-shell nanostructures.

Gluconate controls one-dimensional growth of tellurium nanostructures

In this paper, we show for the first time that by using sodium gluconate-assisted solution route, fine, uniform, and single-crystalline tellurium nanorods and nanowires can be synthesized. Sodium gluconate is a green and safe chemical with strong chelating function, and this property may be useful in the fabrication of nanomaterials, especially one-dimensional (1D) nanomaterials. The sodium gluconate acts as both reducing agent and morphology-directing agent and by adjusting the experimental parameters, the lengths and the diameters of the tellurium nanorods could be further controlled in a certain range. This method is a simple and economical route for 1D nanostructure fabrication and might bring about a novel concept for the synthesis of 1D nanostructures with bio-ligand, sodium gluconate.

Enhancing hope, control and meaningfulness through group-work in the treatment of Parkinson

A new rapid and single step thermal method was successfully developed to synthesize tree-like tellurium (Te) nanostructures at mild condition. Te nanostructures were synthesized using tellurium tetrachloride (TeCl4) as a Te precursor and thioglycolic acid (TGA) as reducing and caping agent. No secondary chemical reducing agent is required to proceed and complete the reaction. A preliminary study on the possibility of developing a solar cell having the fluorine-doped tin oxide (FTO)/TiO2/Te/Pt–FTO structure was also investigated to produce an inexpensive solar cell by Te nanostructures.