• Bulletin of the Korean Chemical Society
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• v.30 no.7
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• pp.1485-1488
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• 2009

A facile, seed-mediated preparation method of trimetallic Au@Pb@Pt core-shell nanoparticles is developed. Au nanoparticles are the template seeds onto which sequentially reduced Pb and Pt are deposited. The trimetallic core-shell structure is confirmed by UV-Vis spectroscopy, TEM and EDS analysis, and cyclic voltammetry. The trimetallic Au@Pb@Pt core-shell nanoparticles show high electrocatalytic activity for formic acid and methanol electrooxidation.

• Journal of the Korean Physical Society
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• v.73 no.10
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• pp.1444-1451
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• 2018

The surface-to-volume ratio of one-dimensional (1D) semiconductor metal-oxide sensors is an important factor for achieving good gas sensing properties because it offers a wide response area. To exploit this effect, in this study, we determined the optimal calcination temperature to maximize the specific surface area and thereby the sensitivity of the sensor. The $In_2O_3$ nanorods were synthesized by using vapor-liquid-solid growth of $In_2O_3$ powders and were decorated with the Pt nanoparticles by using a sol-gel method. Subsequently, the Pt nanoparticle-decorated $In_2O_3$ nanorods were calcined at different temperatures to determine the optimal calcination temperature. The $NO_2$ gas sensing properties of five different samples (pristine uncalcined $In_2O_3$ nanorods, Pt-decorated uncalcined $In_2O_3$ nanorods, and Pt-decorated $In_2O_3$ nanorods calcined at 400, 600, and $800^{\circ}C$) were determined and compared. The Pt-decorated $In_2O_3$ nanorods calcined at $600^{\circ}C$ showed the highest surface-to-volume ratio and the strongest response to $NO_2$ gas. Moreover, these nanorods showed the shortest response/recovery times toward $NO_2$. These enhanced sensing properties are attributed to a combination of increased surface-to-volume ratio (achieved through the optimal calcination) and increased electrical/chemical sensitization (provided by the noble-metal decoration).

• Journal of Electrochemical Science and Technology
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• v.7 no.1
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• pp.27-32
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• 2016

Although the time dependences of the electrocatalytic activities of Pt and Pd nanoparticles during electrochemical operations have been widely studied, the time dependences under nonpolarized conditions have never been investigated in depth. This study reports the changes in the electrocatalytic activities of Pt and Pd nanoparticles with aging in air and in solution. Pt (or Pd) nanoparticle-modified electrodes are obtained by adsorbing citrate-stabilized Pt (or Pd) nanoparticles on amine-modified indium-tin oxide (ITO) electrodes, or by electrodeposition of Pt (or Pd) nanoparticles on ITO electrodes. The electrocatalytic activities of freshly prepared Pt and Pd nanoparticles in the oxygen reduction reaction slowly decrease with aging. The electrocatalytic activities decrease more slowly in solution than in air. An increase in surface contamination may cause electrocatalytic deactivation during aging. The electrocatalytic activities of long-aged Pt (or Pd) nanoparticles are significantly enhanced and recovered by NaBH₄ treatment.

• Journal of Powder Materials
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• v.11 no.3
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• pp.242-246
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• 2004

FePt nanoparticles for high-density magnetic recording media were synthesized by the simultaneous chemical reduction of Fe(acac) $_2$ and Pt(acac) $_2$ with 1,2-hexadecanediol as the reducing reagent. TEM images showed that the shape of as-synthesized FePt nanoparticle was spherical and average particle size was 3 nm. Also, SAD pattern showed that crystal structure was disordered FCC (face centered cubic). These FCC structured nanoparticles were transformed FCT (face centered tetragonal) structure by annealing at 55$0^{\circ}C$ for 30 min in Ar atmosphere. XRD analysis revealed that as-synthesized FePt nanoparticles were transformed from disordered FCC to ordered FCT. Finally, the coercivity of 2 kOe for FePt nanoparticles with FCT structure was obtained by VSM measurement.

• Journal of the Korean institute of surface engineering
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• v.56 no.6
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• pp.420-426
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• 2023

We prepared a highly sensitive hydrogen (H₂) sensor based on Indium oxides (In₂O₃) porous nanoparticles (NPs) loaded with Platinum (Pt) nanoparticle in the range of 1.6~5.7 at.%. In₂O₃ NPs were fabricated by microwave irradiation method, and decorations of Pt nanoparticles were performed by electroless plating on In₂O₃ NPs. Crystal structures, morphologies, and chemical information on Pt-loaded In₂O₃ NPs were characterized by grazing-incident X-ray diffraction, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, respectively. The effect of the Pt nanoparticles on the H₂-sensing performance of In₂O₃ NPs was investigated over a low concentration range of 5 ppm of H₂ at 150-300 ℃ working temperatures. The results showed that the H₂ response greatly increased with decreasing sensing temperature. The H₂ response of Pt loaded porous In₂O₃ NPs is higher than that of pristine In₂O₃ NPs. H₂ gas selectivity and high sensitivity was explained by the extension of the electron depletion layer and catalytic effect. Pt loaded porous In₂O₃ NPs sensor can be a robust manner for achieving enhanced gas selectivity and sensitivity for the detection of H₂.

• Korean Journal of Materials Research
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• v.22 no.8
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• pp.421-425
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• 2012

Two types of Pt nanoparticle electrocatalysts were composited on Pt nanowires by a combination of an electrospinning method and an impregnation method with NaBH4 as a reducing agent. The structural properties and electrocatalytic activities for methanol electro-oxidation in direct methanol fuel cells were investigated by means of scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry. In particular, SEM, HRTEM, XRD, and XPS results indicate that the metallic Pt nanoparticles with polycrystalline property are uniformly decorated on the electro-spun Pt nanowires. In order to investigate the catalytic activity of the Pt nanoparticles decorated on the electro-spun Pt nanowires, two types of 20 wt% Pt nanoparticles and 40 wt% Pt nanoparticles decorated on the electro-spun Pt nanowires were fabricated. In addition, for comparison, single Pt nanowires were fabricated via an electrospinning method without an impregnation method. As a result, the cyclic voltammetry and chronoamperometry results demonstrate that the electrode containing 40 wt% Pt nanoparticles exhibits the best catalytic activity for methanol electro-oxidation and the highest electrochemical stability among the single Pt nanowires, the 20 wt% Pt nanoparticles decorated with Pt nanowires, and the 40 wt% Pt nanoparticles decorated with Pt nanowires studied for use in direct methanol fuel cells.

• The Journal of the Korea institute of electronic communication sciences
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• v.4 no.4
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• pp.301-305
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• 2009

Pt nanoparticles with a narrow size distribution (dia. ~4 nm) were synthesized via an alcohol reduction method and used for the fabrication of hybrid Pt-$SiO_2$ nanoparticles. Also, the self-assembled monolayer of Pt nanoparticles (NPs) was studied as a charge trapping layer for non-volatile memory (NVM) applications. A metal-oxide-semiconductor (MOS) type memory device with Pt NPs exhibits a relatively large memory window. These results indicate that the self-assembled Pt NPs can be utilized for NVM devices. In addition, it was tried to show the control of thin-film thickness of hybrid Pt-$SiO_2$ nanoparticles indicating the possibility of much applications for the MOS type memory devices.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.264-264
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• 2013

Strong metal-support interaction effect is an important issue in determining the catalytic ac-tivity for heterogeneous catalysis. In this study, we investigated the support effect and the role of organic capping layers of two-dimensional Pt nanocatalysts on reducible metal oxide supports under the CO oxidation. Several reducible metal oxide supports including CeO2, Nb2O5, and TiO2 thin films were prepared via sol-gel techniques. The structure, chemical state and optical property were characterized using XRD, XPS, TEM, SEM, and UV-VIS spectrometer. We found that the reducible metal oxide supports have a homogeneous thin thickness and crystalline structure after annealing at high temperature showing the different optical band gap energy. Langmuir-Blodgett technique and arc plasma deposition process were employed to ob-tain Pt nanoparticle arrays with capping and without capping layers, respectively on the oxide support to assess the role of the supports and capping layers on the catalytic activity of Pt catalysts under the CO oxidation. The catalytic performance of CO oxidation over Pt supported on metal oxide thin films under oxidizing reaction conditions (40 Torr CO and 100 Torr O2) was tested. The results show that the catalytic activity significantly depends on the metal oxide support and organic capping layers of Pt nanoparticles, revealing the strong metal-support interaction on these nanocatalysts systems.

• Journal of the Korean Institute of Gas
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• v.15 no.4
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• pp.27-32
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• 2011

Management of gas safety is becoming important with increasing use of gas facilities. U-safety system is being promoted as part of national management of gas, and thus real-time and in-situ gas sensor should be developed. Detection method for When the gas sensor is installed in gas conduit, explosion may be likely, because hydrocarbon gases is usually used the difference of thermal resistance between reference and working electrode. Therefore, it is required to detect the hydrocarbons, such as $CH_4$ and CO, at room temperature via electrochemically catalytic reaction. In this study, Pt nanoparticle was doped on the porous gold powder by electrolytic plating method, and then it was used as catalytic electrode for CO oxidation. For Pt/PAu electrode, approximately 21% of CO conversion was obtained. It is noted that Pt/PAu electrode could be used to react the oxidation of hydrocarbon gases at room temperature via applying of external voltage.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.83-84
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• 2006

In aqueous phase, we directly prepared conducting and photoluminescent nano-structured particles by oxidation polymerization. Thiophene(PT) was initiated by $FeCl_{3}/H_{2}O_{2}$ (catalyst/oxidant) combination system. And, polydispersed core-shell poly(styrene/thiophene) and polyaniline(PANI)-coated multi core-shell polystyrene latex particles were successfully prepared by oxidative and radical polymerization. The resulting latex particles have fine improved luminescence and conductive efficiency and dispersion state due to the PT and PANI shell. Hyper functionalized nanoparticle would be expected to increase the processibility in various electrical and electro-optical fields.