• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2011년도 추계학술대회 초록집
• /
• pp.93-93
• /
• 2011

Nanostructures consisting of $TiO_2$ particles as a core and carbon as a shell ($TiO_2$@C) were prepared by heat treatment of $TiO_2$ nanoparticles at high temperature in a methane atmosphere. X-ray diffraction and transmission electron microscopy showed that a carbon shell layer was formed well. These structures were used as supports for platinum nanoparticles and the hybrid particles exhibit improved catalytic activity and stability toward ORR compared to Pt on a carbon black (Vulcan XC-72R). It is likely that enhanced catalytic properties of the Pt on $TiO_2$@C could be due to the stability of the core-shell support in comparison with carbon black support.

• 한국표면공학회지
• /
• 제50권1호
• /
• pp.1-9
• /
• 2017

Design of novel materials in renewable energy systems plays a key role in powering transportation vehicles and portable electronics. This review introduces the research work of first principles-based computational design for the materials over the last decade to accomplish the goal with less financial and temporal cost beyond the conventional approach, especially, focusing on electrocatalyst toward a proton exchange membrane fuel cell (PEMFC). It is proposed that the new method combined with experimental validation, can provide fundamental descriptors and mechanical understanding for optimal efficiency control of a whole system. Advancing these methods can even realize a computational platform of the materials genome, which can substantially reduce the time period from discovery to commercialization into markets of new materials.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
• /
• pp.280-280
• /
• 2013

In green plants, energy generation is accomplished through light-harvesting photosystem, which utilize abundant visible light and multi-stepwise redox reaction to oxidize water and reduce NADP+, transferring electrons efficiently with active cofactors1. Inspired by natural photosynthesis, artificial solar water-splitting devices are being designed variously. However, the several approaches involving immobilization2, conjugation3, and surface modification4 still have limitations. We have made artificial photosynthesis templates by self-assembling tyrosine-based peptide to mimick photosystem II. Porphyrin sensitizer absorbing blue light strongly was conjugated with the templates and they were hybridized with cobalt oxide through the reduction of cobalt ions in an aqueous solution. The formation of hybrid templates was characterized using TEM, and their water oxidation performance was measured by fluorescence oxygen probe. Our results suggest that the bio-templated assembly of functional compounds has a great potential for artificial photosynthesis.

• 한국식품영양과학회지
• /
• 제26권6호
• /
• pp.1252-1257
• /
• 1997

In order to investigate the immunomodulatory mechanism of white ginseng, the effects of total saponin of Ginsenoside Rb$_2$component on the phagocytosis and reactive oxygen intermediate(ROI) production of mouse peritoneal macrophages were studied. Both phagocytosis assay nitrobluetetrazolium reduction test showed 20$\mu\textrm{g}$/ml concentration of total saponin significantly increased the activity of phagocytosis and production of ROI. Also cytokine gene expression of the macrophages was analyzed using reverse transcription polymerase chain reaction. In the RT-PCR assay, 20$\mu\textrm{g}$/ml concentration of either total saponin or Ginsenoside Rb$_2$increased IL-1 and TNF expression of the macrophages.

• 한국응용과학기술학회지
• /
• 제17권1호
• /
• pp.1-5
• /
• 2000

The selective catalytic reduction(SCR) of nitric oxide by ethane in the presence of oxygen was investigated on Cu-ZSM-5, Co-ZSM-5 and Ga-ZSM-5 catalysts over a range of 400, 450 and $500^{\circ}C$. The catalysts were prepared by ion-exchange method. The composition of the reactant gases were 1000 ppm of NO, 1000 ppm of $C_{2}H_{6}$ and 2.5% of $O_{2}$, and the reaction was conducted in a fixed-bed reactor at 1 atm. For the 20wt% Co-ZSM-5(50) catalyst, the NO conversion reached up to 100%, while the $C_2H_6$ conversion and the CO selectivity were about 50% and 25%, respectively, at $450^{\circ}C$. For the 20wt% Cu-ZSM-5(50) catalyst, the NO conversion and the C2H6 conversion were about 80% and 100%, respectively, but there was no CO produced. The metal ion-exchanged ZSM-5 catalysts exhibited a tendency to increase the NO conversion with the Si/Al ratio of the ZSM-5, that is, NO conversion was inversely proportional to the acidity of the catalysts. But, the effect of the acidity on NO conversion was not so large. From the XRD results of the catalysts before and after SCR reaction it was found that there was no structural change.

• 청정기술
• /
• 제19권3호
• /
• pp.287-294
• /
• 2013

구리-제올라이트 촉매와 Fe-제올라이트 촉매로 과잉산소 분위기에서 일산화질소의 암모니아 선택적 촉매환원반응을 체계적으로 조사하였다. 촉매는 디젤엔진에서의 SCR기술의 적용을 위하여 구리와 철을 $NH_4$-BEA와 $NH_4$-ZSM-5 제올라이트에 이온교환법과 함침법으로 담지시켜 제조하였다. 촉매의 특성은 BET, XRD, FE-TEM과 SEM/EDS를 사용하여 조사하였다. 고정된 반응조건에서 선택적 촉매환원반응의 활성을 조사한 결과에서 구리를 BEA 제올라이트에 이온교환시켜 제조한 촉매가 $200{\sim}250^{\circ}C$의 저온영역에서 탁월한 성능을 나타내었다. $250^{\circ}C$ 이하의 저온에서 구리-제올라이트 촉매가 Fe-제올라이트 촉매보다 높은 반응활성을 나타내었다. BEA 제올라이트에 담지된 촉매가 ZSM-5 제올라이트에 담지된 촉매보다 $250^{\circ}C$ 이하의 저온에서 우수한 반응활성을 나타내었다.

• Journal of Electrochemical Science and Technology
• /
• 제8권1호
• /
• pp.7-14
• /
• 2017

This study aims to examine the influences of substrates/diffusion layers (DL) and oxygen reduction reaction catalysts ($M_{ORR}$) on the performance of $M_{ORR}/IrO_2$/DL-type bifunctional oxygen electrodes for use in polymer electrolyte membrane (PEM)-type unitized regenerative fuel cells (URFC). The $M_{ORR}/IrO_2$/DL electrodes were prepared via two sequential steps: anodic electrodeposition of $IrO_2$ on various DLs and fabrication of $M_{ORR}$ layers (Pt, Pd, and Pt-Ru) by spraying on $IrO_2/DL$. Experiments using different DLs, with Pt as the $M_{ORR}$, revealed that the roughness factor of the DL mainly determined the electrode performance for both water electrolyzer (WE) and fuel cell (FC) operations, while the contributions of porosity and substrate material were insignificant. When Pt-Ru was utilized as the $M_{ORR}$ instead of Pt, WE performance was enhanced and the electrode performance was assessed by analyzing round-trip efficiencies (${\varepsilon}_{RT}$) at current densities of 0.2 and $0.4A/cm^2$. As a result, using Pt-Ru instead of Pt alone provided better ${\varepsilon}_{RT}$ at both current densities, while Pd resulted in very low ${\varepsilon}_{RT}$. Improved efficiency was related to the additional catalytic action by Ru toward ORR during WE operation.

• Korean Chemical Engineering Research
• /
• 제51권2호
• /
• pp.163-170
• /
• 2013

$V_2O_5/TiO_2$계 촉매상에서 $NH_3$에 의한 $NO_x$의 선택적환원은 310의 지구온난화지수를 갖는 $N_2O$의 또 다른 인위적인 배출원이 될 수 있는 것으로 보고되고 있으므로, 본 총설은 화석연료를 연소시키는 화력발전소용 상기 촉매상에서 SCR 탈질반응 동안에 $N_2O$ 생성과 관계되는 주요 변수들의 유의성을 다루고자 한다. $NH_3$-SCR 탈질반응에서 $N_2O$ 배출은 $NH_3$ 산화반응에 더하여 반응 중에 존재하는 $NO_x$와 $NH_3$ 간의 부반응을 통해 일어나 이 부반응들의 정도는 SCR 촉매의 활성성분인 $V_2O_5$의 함량과 조촉매의 종류($WO_3$와 $MoO_3$), 반응온도, $NO_2/NO_x$ 비율, 산소농도, 공간속도, 수분함량, 열처리 등과 같은 유입가스 조건과 운전변수 및 화력발전소 현장에 설치된 상용 SCR 탈질공정에서 격은 촉매의 이력에 크게 의존한다. 상기의 모든 변수들이 탈질반응에서 $N_2O$ 생성과 관계된다고 할지라도, 몇몇 핵심변수들이 $N_2O$ 생성에 미치는 영향과 상용 SCR 공정에서 $N_2O$ 생성을 억제할 수 있는 방안이 고찰되었다.

• 대한화학회지
• /
• 제36권2호
• /
• pp.261-272
• /
• 1992

네자리 Schiff base의 착물 Co(II)(3MeOSED)$(H_2O)_2$을 합성하였다. 이 착물의 균일 산화 활성촉매로서 산소첨가 착물은 DMF와 DMSO 용매에서는 ${\mu}$-peroxo형인 [Co(III)(3MeOSED)(DMF)]$_2O_2$와 [Co(III)(3MeOSED)(DMSO)]$_2O_2$이나 pyridine 용매에서는 superoxo형인 [Co(Ⅲ)(3MeOSED)(Py)]$O_2$로 주어진다. 이들의 CV법과 DPP법에 의한 전기화학적인 특성으로 ${\mu}$-peroxo형은 3단계 환원과정으로 일어나지만, superoxo형은 $O_2$의 prewave를 포함한 4단계 환원과정으로 일어난다. 산소가 포화된 메탄올 용액에서 [Co(III)(3MeOSED)(L)]$O_2(L: CH_3OH)$ 의 균일 산화 활성촉매에 의한 hydrazobenzene-$(H_2AB)$의 산화 주생성물은 trans-azobenzene(t-AB)이 선택적으로 다음과 같은 반응식으로 생성되고 이 때 속도상수는 k = (2.96 ${\pm}$ 0.2) ${\times}$ $10^{-1}$M/sec임을 알았다. $H_2AB$ + Co (Ⅱ)(3MeOSED)$(L_2)+O_2\;{\rightleftarrow^K}$ [Co(III)(3MeOSED)(L)]$O_2{\cdot}H_2AB{\longrightarrow^K}$ Co(II(3MeOSED)$(L)_2$+t-AB+$H_2O_2 $.

• Composites Research
• /
• 제32권6호
• /
• pp.355-359
• /
• 2019

고효율의 물 분해 시스템은 수소 발생 반응(HER)과 산소 발생 반응(OER) 각각에서의 촉매로 인한 전기화학적 반응에서의 효율로 인해 향상되는 높은 과전압의 감소가 수반되어야 한다. 그 중에서도 전이 금속 기반의 화합물(산화물, 황화물, 인화물, 그리고 질화물)은 현재 상용되고 있는 귀금속을 대체할 촉매 재료로써 주목받고 있다. 본 연구에서, 우리는 FESEM 분석을 통해 최적의 단분산된 Co₃[Co(CN)₆]₂ PBAs를 합성하고 XRD, FT-IR 분석을 통하여 결정성을 확인하고 TG-DTA를 통해 PBAs의 열적 거동을 확인하였다. 그리고 합성된 최적의 Co₃[Co(CN)₆]₂ PBAs를 열처리해서 단분산된 Co₃O₄나노 큐브를 합성하였고 XRD를 통해 이의 결정성을 확인하고 OER 측정을 진행하였다. 최종적으로 합성된 Co₃O₄ 나노 큐브는 10 mA·cm^-2의 전류 밀도에서 312 mV의 낮은 과전압과 96.6 mV·dec^-1의 낮은 Tafel slope을 보인다.