• 자원리싸이클링
• /
• 제27권2호
• /
• pp.32-37
• /
• 2018

본 연구는 금속 팔라듐 및 산화 팔라듐의 재활용을 위한 전 단계 연구로 수행되었다. 본 연구에서는 산화 팔라듐(PdO)의 형성을 위한 열역학적 수식들을 확립하였다. 또한 고상의 염화 팔라듐($PdCl_2$)을 염산 용액에 용해시킨 염화 팔라듐 용액을 원료용액으로 사용하였다. 이 원료 용액으로부터 분무열분해 공정에 의하여 평균입도 30 nm 이하의 산화 팔라듐 분체를 제조하였다. XRD 분석 결과 생성된 분체는 오직 PdO 상이었으며 TEM 분석결과 형성된 나노 PdO 입자들은 단결정 상임을 확인하였다. 또한 생성된 PdO 분말의 비표면적은 약 $32m^2/g$이었다.

• Bulletin of the Korean Chemical Society
• /
• 제16권6호
• /
• pp.479-483
• /
• 1995

The synergistic extraction of palladium(Ⅱ) was studied with 1,2-dichloroethane containing thenoyltrifluoroacetone (TTA; HA) and tri-n-octylphosphine oxide (TOPO; S). The main composition of synergistic adduct extracted into 1,2-dichloroethane phase was found to be PdA2S2. The equilibrium constants of the synergistic reaction were calculated. The application of this method to synthetic mixture for the separation of Pd from Pt was developed.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
• /
• pp.139.1-139.1
• /
• 2013

Graphene and graphene oxide (GO) have been modified with palladium nanoparticles (Pd NPs) to develop high performance catalysts for the Sonogashira cross coupling reaction. To understand catalytic performance of Pd NPs on graphene (Pd/G) and Pd NPs on GO (Pd/GO), we monitored their morphological and electronic structural changes before/after Sonogashira reaction using FT-IR, XRD, XPS, and XAFS. Here, we demonstrate that both Pd/G and Pd/GO show high catalytic efficiency toward the Sonogashira reaction, but only Pd/GO revealed excellent recyclability. The remarkable catalytic efficiency of both catalysts is attributed to the high degree of the Pd NP dispersions on supports and thus smaller Pd NPs can provide highly reactive low coordinated Pd atoms. However, we attributed the excellent recyclability of Pd/GO to the presence of oxygen functionalities on GO, which can provide nucleation sites for the detached Pd atoms during the Sonogashira reaction and prevent agglomeration of the Pd NPs since the oxygen functional groups are very reactive to mobile Pd adatoms.

• 한국표면공학회지
• /
• 제25권3호
• /
• pp.107-116
• /
• 1992

The optimum thickness of Pd-Ni plated layers used as an electrical contact film was investigated by evaluating mechanical, thermal and environmental characteristics. The variations of morphologies and chemical compositions were studied by using SEM, EDS and ESCA. As a result of wear test, the wear resistance behavior of the gold plated layers was not changed with the sliding velocity changes. The palladium-nickel plated layer showed better wear resistance than the gold plated layer at low sliding velocity, but it showed poor wear resistance at high sliding velocity. Under the thermal condition of $400^{\circ}C$ in air, the gold thickness of $2\mu\textrm{m}$ without underplate on phosphorous bronze formed copper oxide on the surface layer by rapid diffusion of copper whereas the gold thickness of $0.8\mu\textrm{m}$ deposited on nickel and palladium-nickel underplate was stable at $400^{\circ}C$. Under the sulfur dioxide environments, the gold thickness of $0.3\mu\textrm{m}$ deposited on the nickel thickness of$ 3\mu\textrm{m}$ and the palladium-nickel thickness of $2\mu\textrm{m}$ underplate was more corrosion-resistant than the gold thickness of $2\mu\textrm{m}$ without underplate on phosphorous bronze. Under the nitric acid vapor environment, corrosion resistance of the gold film was superior to an equivalent thickness of the palladium-nickel film.

• 한국표면공학회:학술대회논문집
• /
• 한국표면공학회 2011년도 춘계학술대회 및 Fine pattern PCB 표면 처리 기술 워크샵
• /
• pp.114-114
• /
• 2011

Aluminum oxide surface에 palladium 전처리 공정을 이용하여 무전해 Ni-P 도금을 진행하였다. Ni-P도금액을 산성(pH 4.8~5.3)용액과 알칼리(pH 9~10)용액에 따른 각각의 도금 특성을 평가하였다. 또한 다양한 공정조건(온도, pH, 두께 등...)에서의 도금 특성과 미세구조를 분석하여 $Al_2O_3$막에 적합한 Ni-P 도금액과 공정조건을 개발하였다. 산성 Ni-P 도금액의 경우 pH 5.3, $90^{\circ}C$의 도금 조건에서 phosphorous 12.1 wt.%, 도금속도 274nm/min.의 Ni-P 도금막을 얻을 수 있었다.

• Bulletin of the Korean Chemical Society
• /
• 제35권7호
• /
• pp.1979-1984
• /
• 2014

We have developed an efficient method to generate highly active Pd and PdO nanoparticles (NPs) dispersed on graphene and graphene oxide (GO) by an impregnation method combined with thermal treatments in $H_2$ and $O_2$ gas flows, respectively. The Pd NPs supported on graphene (Pd/G) and the PdO NPs supported on GO (PdO/GO) demonstrated excellent carbon-carbon cross-coupling reactions under a solvent-free, environmentally-friendly condition. The morphological and chemical structures of PdO/GO and Pd/G were fully characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). We found that the remarkable reactivity of the Pd/G and PdO/GO catalysts toward the cross-coupling reaction is attributed to the high degree of dispersion of the Pd and PdO NPs while the oxidative states of Pd and the oxygen functionalities of graphene oxide are not critical for their catalytic performance.

• 한국재료학회지
• /
• 제24권10호
• /
• pp.532-537
• /
• 2014

In this study, highly sensitive hydrogen micro gas sensors of the multi-layer and micro-heater type were designed and fabricated using the micro electro mechanical system (MEMS) process and palladium catalytic metal. The dimensions of the fabricated hydrogen gas sensor were about $5mm{\times}4mm$ and the sensing layer of palladium metal was deposited in the middle of the device. The sensing palladium films were modified to be nano-honeycomb and nano-hemisphere structures using an anodic aluminum oxide (AAO) template and nano-sized polystyrene beads, respectively. The sensitivities (Rs), which are the ratio of the relative resistance were significantly improved and reached levels of 0.783% and 1.045 % with 2,000 ppm H2 at $70^{\circ}C$ for nano-honeycomb and nano-hemisphere structured Pd films, respectively, on the other hand, the sensitivity was 0.638% for the plain Pd thin film. The improvement of sensitivities for the nano-honeycomb and nano-hemisphere structured Pd films with respect to the plain Pd-thin film was thought to be due to the nanoporous surface topographies of AAO and nano-sized polystyrene beads.

• 공업화학
• /
• 제10권4호
• /
• pp.557-562
• /
• 1999

압축천연가스 자동차에서 배출되는 메탄의 산화를 위한 Pd 촉매의 특성을 조사하였다. 알루미나에 담지된 Pd 촉매와 La과 Ce의 조촉매가 첨가된 촉매들을 함침법으로 제조하였다. 메탄산화 반응은 U-튜브 흐름 반응기에서 공간속도(GHSV)가 $72000h^{-1}$이고 반응온도가 $200{\sim}800^{\circ}C$ 범위에서 실험을 수행하였다. 촉매는 XRD, XPS, BET 표면적 및 수소화학흡착 실험에 의하여 특성화되었다. $Pd/{\gamma}-Al_2O_3$ 촉매 제조시 전구체로 $Pd(NO_3)_2$를 사용하고 $600^{\circ}C$로 소성하였을 때 $CH_4$ 산화의 활성이 가장 높았다. 소성된 $Pd/{\gamma}-Al_2O_3$ 촉매에서 palladium은 대부분 PdO로 존재하였으며, 이것의 메탄 산화 반응 활성이 환원된 촉매에 대부분 존재하는 Pd 금속 보다 높았다. 넓은 범위의 redox ratio에서 실험을 반복하면 $Pd/{\gamma}-Al_2O_3$ 촉매의 활성이 감소하고 높은 활성을 보이는 window 영역이 좁아지는 특성을 보였다. 조촉매로 Ce가 첨가된 촉매는 오히려 메탄 산화 활성이 감소하였으며, 조촉매로 La 이 첨가된 $Pd/La/{\gamma}-Al_2O_3$ 촉매는 담체와 Palladium의 열적 안정성이 향상되어 $1000^{\circ}C$에서 aging된 후에도 우수한 활성을 보였다. 또한 $Pd/La/{\gamma}-Al_2O_3$ 촉매의 NO에 의한 $CH_4$ 제거 반응 특성에서 산소가 존재하지 않는 경우 redox ratio가 1.2 근처에서 메탄이 모두 제거되었으나 산소가 존재하면 메탄 제거율이 크게 감소하였다.

• 한국산학기술학회논문지
• /
• 제20권4호
• /
• pp.458-463
• /
• 2019

팔라듐 (Pd)은 촉매 또는 유해 가스 감지물질로서 널리 활용되고 있다. 특히 자체 부피의 900배까지 수소를 흡착할 수 있는 특성 때문에 수소가스 센서로서의 다양한 연구가 이루어졌다. 본 연구에서는 팔라듐 옥사이드 (PdO) 나노구조물을 실리콘 기판 ($SiO_2(300nm)/Si$) 위에 열화학기상증착 장비를 이용하여 $230^{\circ}C{\sim}440^{\circ}C$ 영역에서 3시간 ~ 5시간 동안 성장시켰다. 원료물질인 Pd 파우더는 $950^{\circ}C$에서 기상화시켰고, 이송가스인 고순도 아르곤 가스를 200 sccm으로 흘려주었다. 성장된 팔라듐 옥사이드 나노구조물의 형상을 전계방출 주사전자현미경으로 조사하였고, 결정학적 특성을 Raman 분광학으로 분석하였다. 그 결과 성장된 나노구조물은 PdO 상을 가지고 있었으며, 특정한 기판 온도와 성장 시간에서 나노큐브 형태의 PdO 나노구조물이 성장되었다. 특히 5시간 동안 성장된 $370^{\circ}C$ 영역에서 균일한 형태의 나노큐브 PdO 나노구조물이 성장되었다. 이러한 PdO 나노큐브는 기상-액상-고상 공정으로 성장된 것으로 판단되며, 그래핀 위에 성장되는 PdO 나노큐브 구조는 고감도 수소가스 감지 센서로 활용될 수 있을 것으로 기대된다.

• 대한금속재료학회지
• /
• 제48권4호
• /
• pp.347-352
• /
• 2010

This study reports a novel method off abricating highly sensitive hydrogen gas sensors based on PdO thin films. The PdO thin films with a thickness of 40 nm were deposited on Si substrates under Ar and $O_2$ ambient conditions using a reactive de magnetron sputtering system. Considerable changes in the resistance of the palladium oxide thin films were observed when they were initially exposed to hydrogen gas, as a result of the reduction process. The sensitivity of the PdO thin films was found to be as high as 90%. After the thin films were exposed to hydrogen gas, the nano-sized cracks were discovered to have formed on the surface of the PdO thin films. These types of nano-cracks that formed on the deoxidized PdO thin films are known to play a key role incausing a four-fold reduction of the response time of the absorption process. The results of this study demonstrate that deoxidized PdO thin films can be applied for use in the creation of high-sensitivity hydrogen sensors.