Role of stirring assist during solvothermal synthesis for preparing single-crystal bismuth telluride hexagonal nanoplates

Takashiri, Masayuki; Kai, Shintaro; Wada, Kodai; Takasugi, Soichi; Tomita, Koji

doi:10.1016/j.matchemphys.2016.02.007

Cited by 44 publications

(27 citation statements)

References 28 publications

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“…Here, the XRD results reveal that crystallite size obtained by stirred-assisted hydrothermal process are smaller compared to that reported in other works [35,46], this may be due to the effect of agitation during the hydrothermal treatment which provides more uniform distribution of temperature and concentration [47].…”

Section: Structure Composition and Morphologycontrasting

confidence: 66%

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Correlation Between Morphology Control and Photocatalytic Performance of BiOBr Nano-Microstrutures

et al. 2019

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A systematic approach to optimize the photocatalytic activity of BiOBr nanoparticles was investigated and compared. The resulting BiOBr powders were successfully synthesized through two different pathways: stirred solvothermal and stirred hydrothermal processes under identical synthesis conditions of temperature and time. The composition, morphology, structure and optical properties of as-prepared samples were characterized by means of X-ray diffraction, scanning electron microscopy with energy dispersive X-ray spectroscopy, transmission electron microscopy, diffuse reflectance UV-Visible spectroscopy. Effective surface areas of the synthesized samples were estimated by Brunauer-Emmett-Teller studies. Catalysts prepared by solvothermal process and named (S-BiOBr) were of hierarchical microspheres, while the hydrothermally prepared ones called (H-BiOBr) were nanoflakes, both with a pure crystalline phase. The photocatalytic activities of as-synthesized structures were then examined to evaluate the effect of the synthetic route on the degradation of methyl orange (MO) dye as an organic compound model under simulated solar light irradiation (250 W Xenon lamp, 300 ≤ λ ≤ 800 nm). The photodegradation of MO was monitored by UV-Visible spectroscopy, substantiated by total organic carbon analysis. Hydrothermal process was a non-template method while in solvothermal route ethylene glycol has been used indicating the relative effects of the relationship of medium viscosity on morphology. On the basis of such analysis, the degradation efficiency of S-BiOBr towards MO was found to be 97% compared to 56% using H-BiOBr for 20 ppm concentration of dye. The kinetic analysis confirmed that the reaction rate constant k app was nearly 3 times higher than that of H-BiOBr, suggesting that S-BiOBr displayed the highest photocatalytic activity for the effective decomposition of MO. Graphical AbstractKeywords BiOBr · Hydrothermal/solvothermal syntheses · Micro-nano-structure · Photocatalytic degradation · Solar light irradiation

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Section: Structure Composition and Morphologycontrasting

confidence: 66%

“…(1) is 12.8 nm, which is smaller than that found in the literature [48]. It appears that stirring seems to have an effect on the BiOBr crystallite size as well for hydrothermal and solvothermal processes [47].…”

Section: Structure Composition and Morphologymentioning

confidence: 57%

Correlation Between Morphology Control and Photocatalytic Performance of BiOBr Nano-Microstrutures

et al. 2019

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“…The basic experimental setup has been described in our previous reports. 17,25) This setup was mainly composed of a Teflon-lined stainless-steel autoclave and a hot plate with a magnetic stirrer. To prepare the precursor solution, we used Bi 2 O 3 , TeO 2 , ethylene glycol, poly(vinyl pyrrolidone) (PVP), and sodium hydroxide (NaOH).…”

Section: Methodsmentioning

confidence: 99%

“…Bi 2 Te 3 nanoplates usually contain a single-crystalline phase, with the typical diameter on the order of submicrons and thickness of approximately 30 nm. [15][16][17] The electrical and thermal transports along the top-bottom crystallite plane are quite different from those along the c-axis direction, which is perpendicular to these top-bottom planes. In addition, it has been recently reported that ultrathin nanoplates of Bi 2 Te 3 and related alloys exhibit the characteristics of topological insulators.…”

Section: Introductionmentioning

confidence: 99%

Thermal annealing effect on structural and thermoelectric properties of hexagonal Bi₂Te₃ nanoplate thin films by drop-casting technique

Hosokawa

Wada

Tanaka

et al. 2017

Jpn. J. Appl. Phys.

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High-purity hexagonal bismuth telluride (Bi 2 Te 3 ) nanoplates were prepared by a solvothermal synthesis method, followed by the fabrication of nanoplate thin films by the drop-casting technique. The Bi 2 Te 3 nanoplates exhibited a single-crystalline phase with a rhombohedral crystal structure. The nanoplates had a flat surface with edge sizes ranging from 500 to 2000 nm (average size of 1000 nm) and a thickness of less than 50 nm. The resulting Bi 2 Te 3 nanoplate thin films were composed of well-aligned hexagonal nanoplates along the surface direction with an approximate film thickness of 40 µm. To tightly connect the nanoplates together within the thin films, thermal annealing was performed at different temperatures. We found that the thermoelectric properties, especially the Seebeck coefficient, were very sensitive to the annealing temperature. Finally, the optimum annealing temperature was determined to be 250°C and the Seebeck coefficient and power factor were %300 µV/K and 3.5 µW/(cm&K 2 ), respectively.

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“…Bi 2 (Se x Te 1−x ) 3 nanoplates were synthesized via a solvothermal process 33 . The outline of this process is described in the supplemental information provided in Fig.…”

Section: Methodsmentioning

confidence: 99%

Solvothermal synthesis of n-type Bi2(SexTe1−x)3 nanoplates for high-performance thermoelectric thin films on flexible substrates

Kimura

Mori

Yonezawa

et al. 2020

Sci Rep

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To improve thermoelectric performance of materials, the utilization of low-dimensional materials with a multi-alloy system is a promising approach. We report on the enhanced thermoelectric properties of n-type Bi 2 (Se x te 1−x) 3 nanoplates using solvothermal synthesis by tuning the composition of selenium (Se). Variation of the Se composition within nanoplates is demonstrated using X-ray diffraction and electron probe microanalysis. The calculated lattice parameters closely followed Vegard's law. However, when the Se composition was extremely high, an impurity phase was observed. At a reduced Se composition, regular-hexagonal-shaped nanoplates with a size of approximately 500 nm were produced. When the Se composition was increased, the shape distribution became random with sizes more than 5 μm. To measure the thermoelectric properties, nanoplate thin films (NPTs) were formed on a flexible substrate using drop-casting, followed by thermal annealing. The resulting NPTs sufficiently adhered to the substrate during the bending condition. The electrical conductivity of the NPTs increased with an increase in the Se composition, but it rapidly decreased at an extremely high Se composition because of the presence of the impurity phase. As a result, the Bi 2 (Se x te 1−x) 3 NPTs exhibited the highest power factor of 4.1 μW/(cm•K 2) at a Se composition of x = 0.75. Therefore, it was demonstrated that the thermoelectric performance of Bi 2 (Se x te 1−x) 3 nanoplates can be improved by tuning the Se composition. With the development of information technology including the Internet of things (IoT), the importance of thermoelectric materials that form flexible thin films has increased. This is because thermoelectric materials can directly convert thermal energy to electrical energy and vice versa. The electrical energy generated from the thermal energy via the Seebeck effect can be used to power wireless and wearable sensors 1-4. The thermal energy produced from electrical energy via the Peltier effect can be used to cool electronic devices 5-7. In both cases, the energy conversion efficiency depends on the dimensionless figure-of-merit ZT, defined as ZT = S 2 σT/κ, where S is the Seebeck coefficient, σ is the electrical conductivity, κ is the thermal conductivity, and T is the absolute temperature. In addition, the power factor PF defined by PF = S 2 σ is an important material property. Among thermoelectric materials, bismuth telluride-based alloys which were developed in the 1950s are the most suitable materials for application to IoT technology 8-10. This is because they exhibit the highest thermoelectric properties near 300 K. At this temperature, thermoelectric materials can be used as both thermoelectric generators and Peltier coolers. In particular, ternary alloys such as Bi 2 (Se x Te 1-x) 3 are known to exhibit superior performance compared to binary alloys such as Bi 2 Te 3 and Bi 2 Se 3 11-14. Bismuth telluride-based alloys including binary and ternary alloys commonly have rhombohedral tetradymite-type crystal str...

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Role of stirring assist during solvothermal synthesis for preparing single-crystal bismuth telluride hexagonal nanoplates

Cited by 44 publications

References 28 publications

Correlation Between Morphology Control and Photocatalytic Performance of BiOBr Nano-Microstrutures

Correlation Between Morphology Control and Photocatalytic Performance of BiOBr Nano-Microstrutures

Thermal annealing effect on structural and thermoelectric properties of hexagonal Bi₂Te₃ nanoplate thin films by drop-casting technique

Solvothermal synthesis of n-type Bi2(SexTe1−x)3 nanoplates for high-performance thermoelectric thin films on flexible substrates

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Role of stirring assist during solvothermal synthesis for preparing single-crystal bismuth telluride hexagonal nanoplates

Cited by 44 publications

References 28 publications

Correlation Between Morphology Control and Photocatalytic Performance of BiOBr Nano-Microstrutures

Correlation Between Morphology Control and Photocatalytic Performance of BiOBr Nano-Microstrutures

Thermal annealing effect on structural and thermoelectric properties of hexagonal Bi2Te3 nanoplate thin films by drop-casting technique

Solvothermal synthesis of n-type Bi2(SexTe1−x)3 nanoplates for high-performance thermoelectric thin films on flexible substrates

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Thermal annealing effect on structural and thermoelectric properties of hexagonal Bi₂Te₃ nanoplate thin films by drop-casting technique