• Bulletin of the Korean Chemical Society
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• 제31권6호
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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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• 제34권7호
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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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• 제31권5호
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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.

• 마이크로전자및패키징학회지
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• 제19권2호
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• pp.61-66
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• 2012

Bismuth(III) carbonate basic을 전구체로 사용하여 상온 습식 환원법인 변형 폴리욜법으로 순수 비스무트 나노입자를 합성하면서 캡핑제 또는 표면 안정제의 교체 및 용매의 종류에 따른 비스무트 입자의 제조 특성을 각각 관찰하였다. Polyvinylpyrroldone(PVP) 캡핑제 첨가 조건에서 합성 직후 기준으로 diethylene glycol(DEG) 용매 사용 시 가장 미세한 비스무트 나노입자가 형성되었으며, polyethylene glycol(PEG) 용매 사용 시 가장 조대한 비스무트 나노입자가 합성되었다. 합성 직후에 관찰된 나노입자의 크기와 건조 후 합체 및 엉겨붙음 거동으로 성장한 입자의 크기는 잘 비례하였는데, DEG 용매 사용 시 최종 단계에서 수십 nm~약 300 nm 직경의 가장 미세한 비스무트 입자를 얻을 수 있었다. 또한 캡핑제 및 표면 안정제의 종류에 상관없이 PEG 용매를 사용하여 합성한 경우에서는 광범위한 합체 및 엉겨붙음 거동이 관찰되어 상대적으로 조대한 입자들이 뭉친 형태의 최종 시료가 얻어졌다.

• Journal of Magnetics
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• 제21권2호
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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.

• 한국세라믹학회지
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• 제55권5호
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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).

• 한국세라믹학회:학술대회논문집
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• 한국세라믹학회 2002년도 추계총회 및 연구발표회 초록집
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• pp.99.2-99
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• 2002

• 한국표면공학회지
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• 제48권6호
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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.

• 한국재료학회지
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• 제31권11호
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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.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2002년도 동계연구발표회 논문개요집
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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)