• Bulletin of the Korean Chemical Society
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• v.31 no.6
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• pp.1543-1550
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• 2010

This work presents oxidation of formic acid on Bi-modified Pt nanoparticles of various sizes. The sizes of the studied Pt nanoparticles range from 1.5 to 5.6 nm (detailed in Rhee, C. K.; Kim, B.-J.; Ham, C.; Kim, Y.-J.; Song, K.; Kwon, K. Langmuir 2009, 25, 7140-7147), and the surfaces of the Pt nanoparticles are modified with irreversibly adsorbed Bi. The investigated coverages of Bi on the Pt nanoparticles are 0.12 and 0.25 as determined by coulometry of the oxidation of adsorbed hydrogen and Bi, and X-ray photoelectron spectroscopy. The cyclic voltammetric behavior of formic acid oxidation reveals that the adsorbed Bi enhances the catalytic activity of Pt nanoparticles by impeding a poison-forming dehydration path with a concomitant promotion of a dehydrogenation path. The chronoamperometric results indicate that elemental Bi and partially oxidized Bi are responsible for the catalytic enhancement, when the Bi coverages on Pt nanoparticles are 0.12 and 0.25, respectively. The size effect of Bi-modified Pt nanoparticles in formic acid oxidation is discussed in terms of specific activity (current per unit surface area) and mass activity (current per unit mass).

• Bulletin of the Korean Chemical Society
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• v.34 no.7
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• pp.2167-2170
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• 2013

A low-cost and simple recycling process of waste thermoelectric modules has been investigated using chemical reduction methods. The recycling is separated by two processes, such as dissolving and reduction. When the waste thermoelectric chips are immersed into a high concentration of $HNO_3$ aqueous solution at $100^{\circ}C$, oxide powders, e.g., $TeO_2$ and $Sb_2O_3$, are precipitated in the $Bi^{3+}$ and $HTeO{_2}^+$ ions contained solution. By employing a reduction process with the ions contained solutions, $Bi_2Te_3$ nanoparticles are successfully synthesized. Due to high reduction potential of $HTeO{_2}^+$ to Te, Te elements are initially formed and subsequently $Bi_2Te_3$ nanoparticles are formed. The average particle size of $Bi_2Te_3$ was calculated to be 25 nm with homogeneous size distribution. On the other hand, when the precipitated powders reduced by hydrazine, $Sb_2O_3$ and Te nanoparticles are synthesized because of higher reduction potentials of $TeO_2$ to Te. After the washing step, the $Sb_2O_3$ are clearly removed, results in Te nanoparticles.

• Bulletin of the Korean Chemical Society
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• v.31 no.5
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• pp.1123-1127
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• 2010

We report a simple and quick route for the preparation of high-quality, nearly monodisperse $Bi_2Te_3$, $Sb_2Te_3$, and $Bi_xSb_{2-x}-Te_3$ nanocrystallites. The reactions of bismuth acetate or antimony acetate with Te in oleic acid result in pure phase of $Bi_2Te_3$ or $Sb_2Te_3$ nanoparticles, respectively. Also, ternary $Bi_xSb_{2-x}Te_3$ nanoparticles were successfully synthesized using the same method. The size and morphology of the nanoparticles were controlled by varying the stabilizing agents. The as-prepared nanoparticles are characterized by X-ray diffraction, scanning electron microscope, and high-resolution transmission electron microscope using an energy dispersive spectroscopy.

• Journal of the Microelectronics and Packaging Society
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• v.19 no.2
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• pp.61-66
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• 2012

Bismuth(Bi) nanoparticles were synthesized at room temperature by a modified polyol process using bismuth(III) carbonate basic as precursor. In addition, some characteristics of the synthesis with respect to the exchange of a capping agent/surface stabilizer and solvent type were observed. When polyvinylpyrroldone was added, the finest Bi nanoparticles were synthesized in diethylene glycol(DEG), while the coarsest nanoparticles were formed in polyethylene glycol(PEG). The particle size immediately after synthesis was proportionate to final particle size which was determined by particle growth through coalescence and aggregation during drying. As a result, the finest Bi particles with the diameter range of several tens of nanometers - 300 nm were finally obtained in DEG. Regardless of the type of capping agent/surface stabilizer, extensive coalescence and aggregation behavior occurred in PEG, resulting in final products agglomerated with coarse particles.

• Journal of Magnetics
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• v.21 no.2
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• pp.179-182
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• 2016

In this paper, 10 nm $Fe_3O_4$ nanoparticles were modified on the surface of $2{\mu}m$ flower-like bismuth oxychloride (BiOCl) spheres by a facile co-precipitation method. The results showed that the $Fe_3O_4/BiOCl$ nanocomposites exhibited excellent photocatalytic activity and superparamagnetic property ($M_s=3.22emu/g$) under visible light for Rhodamine B (RhB) degradation. Moreover, the $Fe_3O_4-BiOCl$ photocatalyst possessed magnetic recyclable property, which could maintain high photocatalytic effective even after 20 cycle times. These characteristic indicates a promising application for wastewater treatment.

• Journal of the Korean Ceramic Society
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• v.55 no.5
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• pp.461-472
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• 2018

$Gd_2O_3:Eu/Bi$ nanoparticles were synthesized via spray pyrolysis and applied for the preparation of a luminescent pearl pigment as an anti-counterfeiting material. The luminescence properties were optimized by changing the $Eu^{3+}$ and $Bi^{3+}$ concentration. Ethylene glycol was used as an organic additive to prepare the $Gd_2O_3:Eu/Bi$ nanoparticles. The highest emission intensity was achieved when the total dopant content was 10.0 at.% and the mole fraction of Bi was 0.1. The concentration quenching was mainly due to dipole-dipole interactions between the same activators, and the critical distances were 9.0 and $19.6{\AA}$ for $Eu^{3+}$ and $Bi^{3+}$, respectively. The prepared $Gd_2O_3:Eu/Bi$ powder exhibited an average size of approximately 82.5 nm and a narrow size distribution. Finally, the $Gd_2O_3:Eu/Bi$ nanophosphor coated on the surface of the pearl pigment was confirmed to have good red emission under irradiation from a portable ultraviolet light-emitting diode lamp (365 nm).

• Proceedings of the Korean Ceranic Society Conference
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• 2002.10a
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• pp.99.2-99
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• 2002

• Journal of the Korean institute of surface engineering
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• v.48 no.6
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• pp.303-308
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• 2015

Pd-functionalized ${\beta}-Bi_2O_3$ nanowires are synthesized by thermal evaporation of Bi powder using VLS mechanism followed by Pd coating and annealing. In this study, sensing properties of Pd-functionalized ${\beta}-Bi_2O_3$ nanowires sensor to selected concentrations of $NO_2$ gas were examined. Scanning electron microscopy showed that the nanowires with diameters in a range of 100 - 200 nm and lengths of up to a few tens of micrometers. Transmission electron microscopy and X-ray diffraction confirmed that the products corresponded to the nanowires of ${\beta}-Bi_2O_3$ crystals and Pd nanoparticles. Pd-functionalized ${\beta}-Bi_2O_3$ nanowires sensor showed an enhanced sensing performance to $NO_2$ gas compared to as-synthesized ${\beta}-Bi_2O_3$ nanowires sensor. As synthesized and Pd-functionalized ${\beta}-Bi_2O_3$ nanowire sensors showed responses of 178% - 338% and 196% - 535% at $300^{\circ}C$, respectively, to 0.05 - 2 ppm $NO_2$. In addition, the underlying mechanism of the enhancement of the sensing properties of ${\beta}-Bi_2O_3$ nanowires by Pd-functionalization is discussed.

• Korean Journal of Materials Research
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• v.31 no.11
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• pp.593-600
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• 2021

Herein, a series of g-C₃N₄ modified Bi₂MoO₆ nanocomposites using Bi₂MoO₆ and melamine as original materials are fabricated via sintering process. For presynthesis of Bi₂MoO₆ an ultrasonic-assisted hydrothermal technique is researched. The structure and composition of the nanocomposites are characterized by Raman spectroscopy, X-ray diffraction (XRD), and high-resolution field emission scanning electron microscopy (SEM). The improved photoelectrochemical properties are studied by photocurrent density, EIS, and amperometric i-t curve analysis. It is found that the structure of Bi₂MoO₆ nanoparticles remains intact, with good dispersion status. The as-prepared g-C₃N₄/Bi₂MoO₆ nanocomposites (BMC 5-9) are selected and investigated by SEM analysis, which inhibits special morphology consisting of Bi₂MoO₆ nanoparticles and some g-C₃N₄ nanosheets. The introduction of small sized g-C₃N₄ nanosheets in sample BMC 9 is effective to improve the charge separation and transfer efficiency, resulting in enhancing of the photoelectric behavior of Bi₂MoO₆. The improved photoelectronic behavior of g-C₃N₄/Bi₂MoO₆ may be attributed to enhanced charge separation efficiency, photocurrent stability, and fast electron transport pathways for some energy applications.

• Proceedings of the Korean Magnestics Society Conference
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• 2002.12a
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• pp.100-101
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• 2002

자성가넷 박막은 가시광선 영역에서 큰 값의 페러데이 회전각을 갖고, 광흡수가 적어 우수한 자기광학 특성을 나타내는 재료로 널리 알려져 있다.[1]. 또한 가넷에 Bi를 치환하면 성능지수가 크게 증가하는 것이 알려져 있으므로 현재 연구개발의 초점이 Bi치환 가넷 박막에 모아지고 있다. 가넷박막을 제조하는 방법에 있어 종래에는 스퍼터링법, LPE법, 열분해법 등으로 연구되어 왔으나, 스퍼터링법과 LPE법의 경우 공정이 복잡하고 고가의 장치가 필요한 단점이 있으며, 열분해법의 경우에는 잔존하는 일부 분해가스로 인하여 박막이 다공질화 될 우려가 있다.[2]. (중략)