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전유권,Ohchan Kwon,Yunseong Ji,Ok Sung Jeon,Chanmin Lee,Yong-Gun Shul 한국화학공학회 2019 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.57 No.3
As rechargeable metal-air batteries will be ideal energy storage devices in the future, an active cathode electrocatalyst is required with bi-functionality on both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) during discharge and charge, respectively. Here, a class of perovskite cathode catalyst with a micro-tubular structure has been developed by controlling bi-functionality from different Ru and Ni dopant ratios. A micro-tubular structure is achieved by the activated carbon fiber (ACF) templating method, which provides uniform size and shape. At the perovskite formula of LaCrO3, the dual dopant system is successfully synthesized with a perfect incorporation into the single perovskite structure. The chemical oxidation states for each Ni and Ru also confirm the partial substitution to Bsite of Cr without any changes in the major perovskite structure. From the electrochemical measurements, the microtubular feature reveals much more efficient catalytic activity on ORR and OER, comparing to the grain catalyst with same perovskite composition. By changing the Ru and Ni ratio, the LaCr0.8Ru0.1Ni0.1O3 micro-tubular catalyst exhibits great bi-functionality, especially on ORR, with low metal loading, which is comparable to the commercial catalyst of Pt and Ir. This advanced catalytic property on the micro-tubular structure and Ru/Ni synergy effect at the perovskite material may provide a new direction for the next-generation cathode catalyst in metal-air battery system.
Lee, Jin Goo,Hwang, Ho Jung,Kwon, Ohchan,Jeon, Ok Sung,Jang, Jeongseok,Shul, Yong-Gun The Royal Society of Chemistry 2016 Chemical communications Vol.52 No.71
<P>A hexagonal perovskite BaNiO3 with unusually high-valence nickel(IV) was synthesized under atmospheric and low-temperature conditions by an ethylenediamine-derived wet-chemical route. Secondary phases disappeared with increase in the pH value, and the singlephase BaNiO3 was successfully synthesized at pH 10. The specific surface area was similar to 32 m(2) g(-1), which is significantly enhanced compared to the BaNiO3 (0.3 m(2) g(-1)) synthesized by flux-mediated crystal growth. The BaNiO3 was used as an oxygen-evolution reaction (OER) catalyst, and the specific mass activity was similar to 5 times higher than that of the BaNiO3 synthesized by flux-mediated crystal growth. As a result, the ethylenediamine-derived sol-gel synthesis could be a simple technique to prepare crystalline compounds such as perov-skites and spinels, with unusually high-valence transition metals.</P>
Hwang, Ho Jung,Chi, Won Seok,Kwon, Ohchan,Lee, Jin Goo,Kim, Jong Hak,Shul, Yong-Gun American Chemical Society 2016 ACS APPLIED MATERIALS & INTERFACES Vol.8 No.39
<P>Rechargeable secondary zinc air batteries with superior cyclic stability were developed using commercial polypropylene (PP) membrane coated with polymerized ionic liquid as separators. The anionic exchange polymer was synthesized copolymerizing 1-[(4-ethenylphenyl)methyl]-3-butylimidazolium hydroxide (EBIH) and butyl methacrylate (BMA) monomers by free radical polymerization for both functionality and structural integrity. The ionic liquid induced copolymer was coated on a commercially available PP membrane (Celguard 5550). The coat allows anionic transfer through the separator and minimizes the migration of zincate ions to the cathode compartment, which reduces electrolyte conductivity and may deteriorate catalytic activity by the formation of zinc oxide on the surface of the catalyst layer. Energy dispersive X-ray spectroscopy (EDS) data copolymer-coated separator showed less zinc element in the cathode, indicating lower zinc crossover through the membrane. Ion coupled plasma optical emission spectroscopy (ICP-OES) analysis confirmed over 96% of zincate ion crossover was reduced. In our charge/discharge setup, the constructed cell with the ionic liquid induced copolymer tasted separator exhibited drastically improved durability as the battery life increased more than 281% compared to the pure commercial PP membrane. Electrochemical impedance spectroscopy (EIS) during the cycle process elucidated the premature failure of cells due to the zinc crossover for the untreated cell and revealed a substantial importance must be placed in zincate control.</P>
Ag 담지된 LaSrCoFeO<sub>3</sub> 섬유상 perovskite 촉매의 탄소 입자상 물질의 산화반응
이찬민,전유권,황호정,지윤성,권오찬,전옥성,설용건,Lee, Chanmin,Jeon, Yukwon,Hwang, Ho Jung,Ji, Yunseong,Kwon, Ohchan,Jeon, Ok Sung,Shul, Yong-Gun 한국화학공학회 2019 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.57 No.4
디젤엔진 시스템은 미세먼지 배출의 엄격해진 저감/제어 기준을 충족하기 위해서 산화촉매는 매우 중요한 기술 중에 하나이다. 본 연구에서는 효율적인 soot산화의 촉매로 Ag 나노입자가 loading된 $La_{0.6}Sr_{0.4}Co_{0.2}Fe_{0.8}O_3$ 섬유상 web 촉매를 제시하였다. 제조된 촉매는 FE-SEM, EDS mapping, XRD, XPS 분석을 통해 특성을 평가하였다. Soot 산화성능측정결과 Ag의 효율적인 촉매특성과 증가된 soot입자와 표면의 접촉면적으로 인하여 50% 산화온도 평가($T_{50}=490^{\circ}C$)에서 자연적인 산화보다 $151^{\circ}C$ 가속화된 것을 확인하였다. 따라서 Ag가 loading된 촉매와 3차원적인 web 구조는 soot 산화에 효율적인 촉매후보군으로 확인하였다. The catalytic combustion of particulate matter (PM) is one of the key technologies to meet emission standards of diesel engine system. Therefore, we herein suggest Ag loaded $La_{0.6}Sr_{0.4}Co_{0.2}Fe_{0.8}O_3$ perovskite web catalyst. They were produced by the electrospinning method. FE-SEM, EDS mapping, XRD, XPS were studied to investigate the crystal and morphological structures of loaded Ag particles and $La_{0.6}Sr_{0.4}Co_{0.2}Fe_{0.8}O_3$ perovskite web catalyst. Following the catalytic soot oxidation, we found that the Ag loaded $La_{0.6}Sr_{0.4}Co_{0.2}Fe_{0.8}O_3$ perovskiteweb catalyst showed the higher catalytic activities (e.g., $T_{50}=490^{\circ}C$) than the only $La_{0.6}Sr_{0.4}Co_{0.2}Fe_{0.8}O_3$ perovskite web catalyst (e.g., $T_{50}=586^{\circ}C$). Thus, this finding suggests that Ag loaded $La_{0.6}Sr_{0.4}Co_{0.2}Fe_{0.8}O_3$ perovskite web catalyst can be a promising candidate for enhancing the soot oxidation.