Near infrared nonlinearity in silver telluride-core/carbon-sheath and tellurium-core/carbon-sheath nanostructures synthesized by reduction carbonization approach

Manzoor, Sobia; Liu, Yumin; Fu, Xiuli; Yu, Zhongyuan; Ban, Guijun

doi:10.1007/s10853-014-8391-0

Cited by 5 publications

(4 citation statements)

References 38 publications

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“…[1][2][3]. In addition, Te nanomaterials can be transformed to functional nanocompound by reacting with the other elements [4][5][6][7][8][9][10], which made fabrication of Te nanostructures become a hot research field, such as nanobelts, nanowires, nanotubes, and nanorods [11][12][13]. Nowadays, many methods were used to fabricate Te nanostructures, including physical vapor deposition [14], reflux [15], microwaveassisted method [15], surfactant-assisted approach [16], and solvothermal or hydrothermal methods [17].…”

Section: Introductionmentioning

confidence: 99%

Te hexagonal nanotubes: formation and optical properties

et al. 2016

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Hexagonal Te nanotubes have been synthesized via hydrothermal method. To demonstrate the formation mechanism, the effect of experimental parameters, such as concentration, surfactant, reducing agent, and reaction time, has been investigated. It is found the Te-tubular nanostructure in our experiments is the result of synergistic effect of surfactant, reducing agent, and reaction agent. Further investigation on the photoluminescence (PL) of the Te nanotubes indicates a broad PL peak at about 532 nm (2.33 eV), which is about 6.6 times over its bandgap (0.32 eV). By analyzing the temperature-related Raman spectra, the PL peak has been tentatively ascribed to the surface oxygen-related defect of the Te nanotubes.

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Section: Introductionmentioning

confidence: 99%

Te hexagonal nanotubes: formation and optical properties

et al. 2016

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“…Among them, Ag 2 Te and Ag 7 Te 4 are thermally stable at room temperature . Ag 2 Te is a narrow-band gap semiconductor (i.e., E g of ∼ 0.2 eV) that has drawn considerable attention due to its wide applications in electronic, optical, magnetic, and thermoelectric devices. − Especially for the thermoelectric application, the material possesses many unique advantages such as (1) low thermal conductivity (close to the amorphous limit value) due to the vibration of the Te 2– sublattices and the collision between randomly distributed Ag + ion and Te 2– sublattices; , (2) high electron mobility due to its low effective mass and thereby high electrical conductivity; (3) tunable carrier concentration by doping; and (4) a reversible crystal phase transition from the low-temperature monoclinic structure (β-Ag 2 Te) to the high-temperature fcc structure (α-Ag 2 Te) at about 403 to 423 K . The β-Ag 2 Te is a narrow band gap semiconductor with high electron mobility and low lattice thermal conductivity, whereas the α-Ag 2 Te is a superionic conductor because Ag + cations can easily move through the tellurium anion sublattices .…”

Section: Introductionmentioning

confidence: 99%

Thermoelectric Properties of Ultralong Silver Telluride Hollow Nanofibers

et al. 2015

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Ultra-long Ag x Te y nanofibers were synthesized for the first time by galvanically displacing electrospun Ni nanofibers. Control over the nanofiber morphology, composition and crystal structure was obtained by tuning the Ag + concentrations in the electrolytes. While Te-rich branched p-type Ag x Te y nanofibers were synthesized at low Ag + concentrations, Ag-rich nodular Ag x Te y nanofibers were obtained at high Ag + concentrations. The Te-rich nanofibers consist of coexisting Te and Ag 7 Te 4 phases, and the Ag-rich fibers consist of coexisting Ag and Ag 2 Te phases. The energy barrier height at the phase interface is found to be a key factor affecting the thermoelectric power factor of the fibers. A high barrier height increases the Seebeck coefficient, S, but reduces the electrical conductivity, σ, due to the energy filter effect. The Ag 7 Te 4 /Te system was not competitive with Ag 2 Te/Ag system due to its high barrier height where the increase in S could not overcome the severely diminished electrical conductivity. The highest power factor was found in the Ag-rich nanofibers with an energy barrier height of 0.054 eV. INTRODUCTIONThe rising cost of compliance to laws and regulations (from the Clean Air Act to Geologic Sequestration) for consuming non-renewable energy resources is the key driver to improve the efficiency of environmentally-friendly and renewable energy generation. 1 Thermoelectric materials offer simple, silent and reliable solid-state energy conversion devices due to their unique ability to directly convert heat into electricity and viceversa without moving parts or bulk fluids. The efficiency of a thermoelectric device can be determined by the thermoelectric figure-of-merit (ZT), given by ܼܶ = ܵ ଶ ߪܶ/ߢ. Here S, σ, κ, T, and S 2 σ are the Seebeck coefficient, electrical conductivity, thermal conductivity, temperature, and power factor, respectively. Nonetheless, the interrelationships of these key parameters in a bulk material tend to offset one another making it difficult to improve ZT. 2 Recent research in low-dimensional, especially one-dimensional (1-D) thermoelectric nanostructures, has invigorated the field by identifying quantum confinement, the energy filtering effect, and stronger phonon scattering effects to enhance S 2 σ and reduce κ. 3-5 Quantum confinement shifts the Fermi level away from the conduction band, creating a greater energy difference between them thereby improving the power factor. 6 Energy filtering enhances the average carrier energy by filtering out low energy carriers at grain boundaries or interfaces, thus increasing the Seebeck coefficient and optimizing the power factor. 7 Stronger phonon scattering at the grain boundaries and interfaces is anticipated in 1-D nanostructures due to their larger surface-to-volume ratio, which can significantly decrease the thermal conductivity. Among 1-D thermoelectric materials, nanotubes benefit from their unique wall thickness, which provides an extra de-

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“…Compared with initial Te NWs, the larger diameter of newly formed broken NWs can be attributed to a morphological evolution from the Te NWs to broken NWs. The formation of the broken NWs likely reflects relaxation of the strong mechanical stress in the galvanic replacement reaction. − …”

Section: Resultsmentioning

confidence: 99%

Synthesis of Ultralong, Monodispersed, and Surfactant-Free Gold Nanowire Catalysts: Growth Mechanism and Electrocatalytic Properties for Methanol Oxidation Reaction

Guo

Zhang

et al. 2017

J. Phys. Chem. C

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The understanding of factors influencing the growth of nanowires is critical for the precise control of the nanowire morphologies and the design of active nanowire catalysts for fuel cell reactions. While the formation of gold nanoparticles followed by self-assembly into short strings of nanowires is known, little is understood in terms of the control of the morphologies and surface properties toward enhanced electrocatalytic properties. This report describes novel findings of an investigation of the growth mechanism of ultralong, highly monodispersed, and surface surfactant-free gold nanowires (Au NWs) synthesized by a galvanic replacement reaction of Te NWs as an initial template. By manipulating reaction time and Au precursor concentration, an aggregative growth mechanism in terms of 1D and 3D growth pathways for the NW length and diameter, respectively, is revealed to be operative in the template-directed Au NW formation process, shinning some fresh insight into the controllability of the nanowire morphologies. In contrast to the use of various organic surfactants in most previous synthesis of Au NWs and catalysts, the surfactant-free Au NWs synthesized in this work have been demonstrated to exhibit enhanced electrocatalytic activities for methanol oxidation reaction, outperforming those for Au NWs with surface surfactants and Au NP counterparts.

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Near infrared nonlinearity in silver telluride-core/carbon-sheath and tellurium-core/carbon-sheath nanostructures synthesized by reduction carbonization approach

Cited by 5 publications

References 38 publications

Te hexagonal nanotubes: formation and optical properties

Te hexagonal nanotubes: formation and optical properties

Thermoelectric Properties of Ultralong Silver Telluride Hollow Nanofibers

Synthesis of Ultralong, Monodispersed, and Surfactant-Free Gold Nanowire Catalysts: Growth Mechanism and Electrocatalytic Properties for Methanol Oxidation Reaction

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