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권오훈,주상욱,신지영,김건태 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0
In perovskites, exsolution of transition metals has been attracted attention as a technique for smart catalyst design on the energy applications due to its superior features. The exsolution produces electro-catalytic nanoparticles evenly and the exsolved nanoparticles are socketed on the perovskite oxide surface, which can prevent carbon coking and increase redox stability. When a dopant is present in the perovskite, the exsolution of the dopant is often affected by the amount of oxygen vacancies. However, the mechanism for co-segregation of dopant with oxygen vacancies is still unclear. Here, we report exsolution characteristics for B-site transition metals on a redox stable layered perovskite oxide. The uniqueness of the exsolution of each transition metal is confirmed by density functional theory (DFT) calculations and transmission electron microscopy (TEM) analysis.
김현민,권오훈,신지영,김건태 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0
Compared to other energy conversion devices, solid oxide fuel cells (SOFCs) are advantageous energy devices offering notable conversion efficiency, fuel flexibility and long-term stability. To enhance commercial applicability of the SOFC system, symmetrical solid oxide fuel cells (S-SOFCs) have been reported because of the simplified fabrication processing, reduction in cost and minimized thermal stress issues between electrode and electrolyte. However, material selection for S-SOFC electrode is difficult since S-SOFC electrodes need to be stable in both oxidizing and reducing environment. Hereby, we suggest a strontium-doped Pr0.5Ba0.5-xSrxFeO3-d (x=0 ~ 0.4) series. Good redox stability, sufficient electrical conductivity in both environments and high-power density output demonstrates the Pr0.5Ba0.5-xSrx FeO3-d (x=0 ~ 0.4) series as favorable choices for S-SOFC electrodes.
주상욱,권오훈,신지영,김건태 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.1
Layered perovskite oxides have received extensive attention as promising cathode materials for SOFCs because of their faster diffusion coefficient and transport kinetics of oxygen compared to those of ABO<sub>3</sub>-type perovskite oxides. In this study, we investigate the effect of Fe doping into YBa<sub>0.5</sub>Sr<sub>0.5</sub>Co<sub>2</sub>O<sub>5+δ</sub> on the oxygen reduction reaction (ORR) and evaluate the optimal Fe amount through the analysis of the structural characteristics, electrical properties, and electrochemical performance of YBa<sub>0.5</sub>Sr<sub>0.5</sub>Co<sub>2-x</sub>Fe<sub>x</sub>O<sub>5+δ</sub> (x=0, 0.25, 0.5, and 0.75). The optimal amount of Fe substitution is assessed as 12.5% of the B site (YBa<sub>0.5</sub>Sr<sub>0.5</sub>Co<sub>1.75</sub>Fe<sub>0.25</sub>O<sub>5+δ</sub>), showing the maximum power density (1.57 W·cm<sup>-2</sup>) at 600 ℃. Moreover, the Fe-doped samples exhibit increased chemical stability under practical operating condition. The results suggest that YBa<sub>0.5</sub>Sr<sub>0.5</sub>Co<sub>1.75</sub>Fe<sub>0.25</sub>O<sub>5+δ</sub> is a promising cathode material for intermediate-temperature solid oxide fuel cells (IT-SOFCs).
Bi-functional metal oxide catalyst with the novel infiltration for rechargeable metal-air battery
김선아,권오훈,신지영,김건태 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0
To realize feasible devices for sustainable energy storage, electrocatalysts should have competitive price and effective bifunctional reactivity for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). In this regard, hybrid catalysts were suggested to satisfy the requirements. The infiltration technique is selected for the fabrication due to its simplicity and easiness. Herein, we designed a bifunctional hybrid catalyst (NSC@Co3O4) consisting of a Nd0.5Sr0.5CoO3 (NSC) perovskite and Co3O4 nanoparticles. Interestingly, the infiltration tried directly on the powder enhanced the onset potential and the limiting current for ORR and OER with unique microstructure. Furthermore, NSC@Co3O4 shows outstanding cell performance with the discharge-charge voltage gap of 0.5 V and excellent stability during 60 h for hybrid Li-air batteries, whereas those were 1.18 ~ 1.64 V and 40 h for Pt/C.
( Yunfei Bu ),권오훈,김건태 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.1
Considerable efforts have been devoted to the developing and fabrication of low-cost, precious metal-free electrocatalysts with high performance for the storage of renewable energies. Perovskite, due to its structural and compositional flexibility as well as high intrinsic catalytic activity, has been attracting lots of attentions. Perovskites with large particle sizes synthesized via traditional synthesis routes are suffering from the low mass activities. In this work, double-perovskite PrBa<sub>0.5</sub> Sr<sub>0.5</sub>Co<sub>1.5</sub>Fe<sub>0.5</sub>O5+δ mesoporous nanofiber (PBSCF-F) was prepared via an electrospinng process, which exhibited uniform diameter and high surface areas (near 7.7 times than powders calcined at same temperature), greatly enhancing both of the oxygen reduction reaction and oxygen evolution reaction performance. Benefiting from the unique morphological and superior bifunctional activities, PBSCF-F exhibited remarkable cell performance and exceptionally high stability for hybrid Li-air battery.
Application of Pt-N doped carbon based catalyst for the outstanding stability for PEMFC
김정원,김창민,( Yunfei Bu ),권오훈,주용완,신지영,김건태 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.1
Platinum (Pt)-based electrodes are the most widely used oxygen reduction reaction (ORR) electrocatalysts in proton exchange electrolyte fuel cell (PEMFC). Although fuel cell using platinum as cathode catalyst has the outstanding performance for ORR, it has plenty of drawbacks, such as CO poisoning effects, high cost of Pt catalyst for commercialization, and unfavorable stability. In this regard, the carbon based electrodes, such as graphene, carbon nanotubes, and carbon black, have been widely investigated in order to overcome the drawbacks of platinum catalysts. In this study, the electrochemical properties and the stability of the advanced Pt-N doped carbon based electrode were reported compared with conventional Pt-based electrodes. As a result, this advanced Pt-N doped carbon based catalyst showed the significantly high stability and electrical performance, 1.7W mg<sup>-1</sup><sub>pt</sub> , compared with commercial Pt-based catalyst (Pt/C) , 1.4W mg<sup>-1</sup><sub>pt</sub> at 70℃.