• Journal of Hydrogen and New Energy
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• v.29 no.5
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• pp.450-457
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• 2018

To design the practical core-shell electrocatalysts, combination of core and shell materials is important to meet catalytic activity and durability target. In general, Pd is considered as a good core material due to its best activity caused by strain/ligand effect. Preparing Pd nanoparticles can be a starting point in fabricating core-shell type electrocatalysts, much simplified Pd preparing process is suggested by using carbon monoxide (CO) as a reducing agent and/or capping agent. The solvent composition and reaction temperature can control to nanosheet, tetrahedron, and sphere without using additional stabilizer. Among them, Pd nanosheet which has mainly (111) plane showed about 3 times higher electrocatalytic activity for oxygen reduction reaction (ORR) to the spherical Pd nanoparticles. The enhanced ORR activity of Pd nanosheets can be attributed to the exposure of Pd (111) surface and the high electrochemical surface area. Therefore, we demonstrated that the shape of Pd nanomaterials is easily controlled via a facile reduction method using CO, and (111) plane-oriented Pd nanosheets can be a promising ORR catalysts and core material for polymer electrolyte fuel cells (PEFCs).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.160-161
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• 2008

$SnO_2$는 n형 반도체로써 3.6 eV의 큰 밴드갭을 가지는 물질로 CO와 NOx 가스에 좋은 감도를 나타내는 것으로 보고되고 있다. 문헌에 따른 일반적인 $SnO_2$ 가스센서는 후막이나 벌크형태로 제작되었다. 근래에는 가스감응체가 $SnO_2$ 나노선 형태인 가스센서가 활발한 연구 중에 있다. 본 논문에서는 기판 위에 서로 분리된 전극 패턴에 Au를 촉매로 하여 네트워크 구조로 된 $SnO_2$ 나노선이 합성되었다. 제작된 가스센서에 Pd 도핑에 따른 영향을 알아보기 위하여 1.8 mM의 Pd 용액 ($PdCl_2{\cdot}xH_2O$ 3 mg + $H_2O$ 10 ml)을 이용하여 센서에 도핑하였다. 측정 시스템에서 $NO_2$ 가스에 대한 센서의 특성을 분석한 결과 도핑하지 않은 $SnO_2$ 센서보다 20%정도의 감도가 개선되었다.

• Resources Recycling
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• v.26 no.3
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• pp.26-31
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• 2017

LIX 63 showed a selectivity for the extraction of Pd(II) over other PGMs, such as Pt(IV), Ir(IV) and Rh(III) from 6 M HCl solution. Moreover, HCl solution has significant effect on the oxidation-reduction reaction between Ir(IV) and LIX 63. Therefore, the applicability of employing LIX 63 for the separation of the 4 PGMs was investigated from 3 M HCl solution. From 3 M HCl solution, only Pd(II) was selectively extracted by LIX 63 and its extraction percentage was higher than from 6 M HCl solution. Extraction of the Pd(II) free raffinate with TBP led to the selective extraction of Pt(IV). After oxidation of Ir(III) with $NaClO_3$ to Ir(IV), extraction of the Pt(IV) free raffinate with Aliquat 336 selectively extracted Ir(IV). For each extraction step, optimum stripping conditions were obtained. By this process, it was possible to separate the 4 PGMs by solvent extraction from 3 M HCl solution.

• Korean Chemical Engineering Research
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• v.45 no.4
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• pp.351-355
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• 2007

It is necessary to convert butene-2 into butene-1 with higher added-values through positional isomerization. In this study, hydro-isomerization of butene-2 with hydrogen over Pd/alumina catalysts was investigated in a fixed bed reactor. The yield of butene-1 over Ld-265 catalyst was higher than that over other catalysts. The yield of butene-1 was highest (5.3%) under the conditions of reaction temperature of $75^{\circ}C$, reaction pressure of 150 psig, 2-butene flow rate of 48 cc/h and hydrogen flow rate of 3 cc/min. We conducted simulation for the process composed of a hydro-isomerization reactor and a distillation tower. In the case of 78% of tray efficiency, we obtained over 99% pure butene-1 through a distillation tower with 171 steps (R=120).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.4
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• pp.271-275
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• 2011

In this paper, thermal stability of palladium germanide (Pd germanide) is analyzed for high performance Schottky barrier germanium metal oxide semiconductor field effect transistors (SB Ge-MOSFETs). Pd germanide Schottky barrier diodes were fabricated on n-type Ge-on-Si substrates and the formed Pd germanide shows thermal immunity up to $450^{\circ}C$. The barrier height of Pd germanide is also characterized using two methods. It is shown that Pd germanide contact has electron Schottky barrier height of 0.569~0.631 eV and work function of 4.699~4.761 eV, respectively. Pd germanide is promising for the nanoscale Schottky barrier Ge channel MOSFETs.

• Journal of the Korean Chemical Society
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• v.55 no.1
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• pp.92-97
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• 2011

The effect of Group I alkali acetate promoters on vinyl acetate (VA) synthesis was evaluated. Catalyst product selectivity and ethylene conversion are compared to the unpromoted catalyst in the fixed-bed reactor with oxidation reaction of ethylene and acetic acid in gaseous phase over Pd-Au/$SiO_2$ catalyst. It was found that: a) the promoters were stabilized on the catalyst surface, b) common effect for the alkali promoted Pd-Au catalysts increaseed in product selectivity and ethylene conversion compared to unpromoted catalyst (these effects increase from top to the bottom of Group I). These promoting effect is due to the common-ion effect of acetate, present in the reaction, resulting in an increase in the activity of the catalyst. In addition a complementary theory for the effect of Au in the structure of the catalyst is proposed the imposition of distribution of palladium particles through decreasing the particle's diameter.

• Bulletin of the Korean Chemical Society
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• v.28 no.11
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• pp.1945-1950
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• 2007

Two fluorene-based conjugated copolymers containing hexyl-thiophene derivatives, PF-1T and PF-4T, were synthesized via the palladium-catalyzed Suzuki coupling reaction. The number-average molecular weights (Mn) of PF-1T and PF-4T were found to be 19,100 and 13,200, respectively. These polymers were soluble in common organic solvents such as chloroform, chlorobenzene, toluene, etc. The UV-vis absorption maximum peaks of PF-1T and PF-4T in the film state were found to be 410 nm and 431 nm, respectively. Electrochemical characterization revealed that these polymers have low highest occupied molecular orbital (HOMO) levels, indicating good resistance against oxidative doping. Thin film transistor devices were fabricated using the top contact geometry. PF-1T showed much better thin-film transistor performance than PF-4T. A thin film of PF- 1T gave a saturation mobility of 0.001-0.003 cm2 V?1 s?1, an on/off ratio of 1.0 × 105, and a small threshold voltage of ?8.3 V. To support TFT performance, we carried out DSC, AFM, and XRD measurements.

• Korean Journal of Crystallography
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• v.1 no.2
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• pp.66-75
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• 1990

The Pd-Te system has been investigated by differential thermal analysis, X-ray diffration, electron probe microanalysis and reflected light microscopy. New phase relations in 0-50at% Te portion of the binary system are proposed. Eight binary phases exist in the system:Pd17Te4, Pd20Te7.PdsTe3, P477e3, P497e4, P637e2, PeTe and PaTe2. Of these, P677e3 is a newly reported phase. P4177e4 is cubic, space group Fd3c, with a=12.678(5)A. The X-ray powder data of PdsTe3, indexed on an orthorhombic cell, give a= 12.843(3), b=15.126(3), c: 11.304(2)A and those of PdTTe.1, indexed on a monoclinic cell, give a=7.444(1), b= 13.918(2) , c=8.873(2)A. p =92.46(2). Some physical and optical properties of synthetic phases in the system are also reported.

• Membrane Journal
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• v.21 no.4
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• pp.345-350
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• 2011

No investigation has yet been accomplished to screen the boron-doped effects on vanadium based metal membranes. The synthesis, hydrogen permeation properties and chemical stability of a novel Pd-coated $V_{99.8}B_{0.2}$ alloy membrane are presented in this report. Hydrogen permeation experiments have been performed to investigate the hydrogen transport properties through the Pd-coated $V_{99.8}B_{0.2}$ alloy membrane in the absolute pressure range 1.0~3.0 bar under pure hydrogen, hydrogen-carbon dioxide gas mixture at $400^{\circ}C$. The maximum hydrogen permeation flux was $48.5mL/min/cm^2$ for a 0.5 mm thick membrane under pure hydrogen. This results offer new direction in the synthesis of novel non-Palladium-based metal membranes for hydrogen separation in water-gas shift reaction.

• The Journal of the Korean dental association
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• v.52 no.2
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• pp.96-104
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• 2014

The aim of this study was to investigate the frequency of positive patch test reaction to dental materials in patients with oral mucosal diseases. Epicutaneous patch test was performed in 110 patients with oral mucosal diseases; 41 patients with oral lichen planus(OLP), 44 patients with burning mouth syndrome(BMS), 25 patients with other oral mucosal diseases including recurrent aphthous ulcer and mucous membrane pemphigoid. The obtained results were as follows: Oral gold restorations were most common in patents with oral mucosal diseases and porcelain fused metal crown, implant appeared in the order. 33 of 110 patients did not appear skin reactions (negative, 30%) and 77 patients (positive, 70%) had skin reactions including redness, rash, blisters. Dental materials causing positive reaction to patch test were mainly as gold-sodium-thiosulfate (26.7%), nickel sulfate(Ni) (22.7%), cobalt chloride(Co) (14.7%), palladium chloride(Pd) (11.9%), potassium dichromate (10.7%) in order, respectively. In conclusion, old metal restorations could be the cause of oral mucosal diseases and epicutaneous patch test could be used as a tool to improve the oral conditions.