• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2001년도 추계학술대회 논문집 전기물성,응용부문
• /
• pp.165-167
• /
• 2001

Emitter injection efficiency of p+/n-buffer Junction with Gaussian impurity distribution is presented. This model takes into account the variation of the carrier lifetime with injection level which allows a unified interpretation of the injection efficiency for all injection level. The injected carrier density and injection efficiency of the anode are calculated as a function of the current density with the low level lifetime as a parameter for different thicknesses of the anode. The analytical results agree well with simulation.

• Carbon letters
• /
• 제4권3호
• /
• pp.121-125
• /
• 2003

The Pt-Ru/Carbon as an anode catalyst supported on the commercial activated carbon (AC) having high surface area and micropore was characterized for application of Direct Methanol Fuel Cell (DMFC). The Pt-Ru/AC anode catalyst used in this experiment showed the performance of $600\;mA/cm^2$ current density at 0.3 V. The borohydride reduction process using $NaBH_4$, denoted as a process A, showed much higher current and power densities than process B prepared by changing the reduction and washing process of process A. The particle sizes are strongly affected by the reduction process than the specific surface area of raw active carbon and the sizes are almost constant when the specific surface area of carbon are over than the $1200\;m^2/g$. Smaller particle size of catalyst and more narrow intercrystalite distance increased the performance of DMFC.

• 한국전기화학회:학술대회논문집
• /
• 한국전기화학회 2004년도 수소연료전지공동심포지움 2004논문집
• /
• pp.195-198
• /
• 2004

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2006년도 추계학술대회
• /
• pp.411-412
• /
• 2006

PEM(proton exchange membrane) fuel cell have been receiving considerable interest as power source because of high-energy efficiency. However by using reforming hydrogen gas, CO poisoning occur in anode. To improve CO tolerance PtRu catalysts were prepared by galvanostatic pulse electrodeposition. The composition(atomic ratio) of catalysts are controllable by using different concentrations of PtRu solutions. Also, the particle sizes of PtRu on carbon are similar to about $3.5{\sim}4nm$ regardless of concentration.

• Journal of Electrochemical Science and Technology
• /
• 제13권3호
• /
• pp.354-361
• /
• 2022

In a direct methanol fuel cell system (DMFC), one of the drawbacks is methanol crossover. Methanol from the anode passes through the membrane and enters the cathode, causing mixed potential in the cell. Only Pt-based catalysts are capable of operating as cathode for oxygen reduction reaction (ORR) in a harsh acidic condition of DMFC. However, it causes mixed potential due to high activity toward methanol oxidation reaction of Pt. To overcome this situation, developing Pt-based catalyst that has methanol tolerance is significant, by controlling reactant adsorption or reaction kinetics. Pt/C decorated with phosphate ion was prepared by modified polyol method as cathode catalyst in DMFC. Phosphate ions, bonded to the carbon of Pt/C, surround free Pt surface and block only methanol adsorption on Pt, not oxygen. It leads to the suppression of methanol oxidation in an oxygen atmosphere, resulting in high DMFC performance compared to pristine Pt/C.

• 대한환경공학회지
• /
• 제32권4호
• /
• pp.357-362
• /
• 2010

미생물연료전지는 미생물이 유기물을 분해하면서 전기를 발생시킨다. 미생물연료전지는 여러 분야로 응용이 가능하며 현재 생산되는 전력이 낮기 때문에 상용화가 되기 위해서는 미생물연료전지(MFC)의 전력을 증진시키는 방안 연구가 필요하다. 미생물연료전지(MFC)의 전력을 증진시키기 위해서는 산화, 환원전극에서의 활성화전압손실(Activation losses)과 저항전압손실(Ohmic losses)을 줄여야 하며 활성화전압손실과 저항전압손실의 정확한 측정과 이를 줄이기 위한 인자를 찾는 것이 중요하다. 본 연구에서는 H형태의 미생물연료전지(Microbial Fuel Cell, MFC)에서 전류차단법(Current interruption)을 이용하여 산화전극 및 환원전극에서의 활성화 전압손실과 저항전압손실을 측정하였다. H형태의 미생물연료전지에서 백금이 코팅된 전극(0.5 $mg/cm^2$; 10% Pt)을 환원전극으로 이용하였음에도 환원전극 전압손실이 산화전극 전압손실보다 4배 가량 큼을 알 수 있었다. 전류차단법(Current interruption)에 의하여 구한 저항전압손실 값(1146 ${\Omega}$) 과 impedance에 의하여 구한 내부저항(1167 ${\Omega}$)은 거의 일치하였다. 또한 산화, 환원전극 활성화 전압손실의 합은 전지(cell)의 활성화 전압손실과 일치하였다.

• Korean Chemical Engineering Research
• /
• 제45권4호
• /
• pp.345-350
• /
• 2007

고분자전해질 연료전지를 OCV(open circuit voltage)나 저가습 조건하에서 운전하면 고분자전해질 막의 열화 (degradation)가 가속화된다. 그런데 왜 이러한 조건에서 막 열화가 심하게 되는지 명확히 규명한 연구결과들이 없다. 본 연구에서는 OCV/저가습 조건에서 운전 중 막의 수소 투과도, I-V 분극곡선 변화를 측정하고 응축수 내 불소이온 방출 속도(FER)와 셀 내 생성된 과산화수소 농도를 측정하였다. 그리고 기존의 과산화수소와 라디칼에 의한 고분자막 열화 메카니즘이 실험결과를 설명할 수 있는지 비교 검토하였다. OCV/저가습 조건에서 고분자 막 열화가 잘 되는 것은 건조한 anode의 Pt 촉매 상에서 Pt와 수소원자가 결합된 상태 즉 [PtH]로의 반응이 잘 일어나고 이 [PtH]가 OCV 조건에서는 $HO_2{\cdot}$를 형성할 수 있는 조건을 만족하기 때문으로 보인다.

• 대한환경공학회지
• /
• 제30권4호
• /
• pp.453-458
• /
• 2008

본 연구는 생활하수 최종처리수의 색도, 잔류 유기물질 제거 및 소독에 관한 연구를 Nb/Pt Anode 전극으로 구성된 전기분해장치를 이용하여 수행하였다. RNO는 OH$\cdot$에 의하여 빠르게 탈색시키며, 전류세기 5 A, 10 A, 15 A에서 RNO의 2차 분해속도는 각각 $\frac{0.223l}{mg{\cdot}min}$, $\frac{1.679l}{mg{\cdot}min}$, $\frac{2.322l}{mg{\cdot}min}$로 96% 이상의 r$^2$ 조사되었다. 회분식 전기분해장치에서 전류세기 15 A와 초기 pH 5, 7.5, 9일 때 15분 후 COD$_{Mn}$ 농도는 4 mg/L 미만, 색도는 5도 미만, 일반세균은 불검출로 먹는물 수질 기준값으로 조사되었다. 전기분해 연속 시스템의 HRT 3.7$\sim$49.2분에서 유리염소는 0.2$\sim$0.7 mg/L, 일반세균은 불검출, 색도는 5도 미만과 THMs는 0.017 mg/L이다. 그러므로 Nb/Pt anode 전기분해 공정은 소독뿐만 아니라 생물학적 처리수의 재이용 기술로 적용될 수 있다.

• Nuclear Engineering and Technology
• /
• 제49권7호
• /
• pp.1451-1456
• /
• 2017

Finding technical issues associated with equipment scale-up is an important subject for the investigation of pyroprocessing. In this respect, electrolytic reduction of 1 kg $UO_2$, a unit process of pyroprocessing, was conducted using graphite as an anode material to figure out the scale-up issues of the C anode-based system at pilot scale. The graphite anode can transfer a current that is 6-7 times higher than that of a conventional Pt anode with the same reactor, showing the superiority of the graphite anode. $UO_2$ pellets were turned into metallic U during the reaction. However, several problems were discovered after the experiments, such as reaction instability by reduced effective anode area (induced by the existence of $Cl_2$ around anode and anode consumption), relatively low metal conversion rate, and corrosion of the reactor. These issues should be overcome for the scale-up of the electrolytic reducer using the C anode.

• Environmental Engineering Research
• /
• 제15권2호
• /
• pp.71-78
• /
• 2010

To understand the effects of acclimation schemes on the formation of anode biofilms, different electrical performances are characterized in this study, with the roles of suspended and attached bacteria in single-chamber microbial fuel cells (MFCs). The results show that the generation of current in single-chamber MFCs is significantly affected by the development of a biofilm matrix on the anode surface containing abundant immobilized microorganisms. The long-term operation with suspended microorganisms was demonstrated to form a dense biofilm matrix that was able to reduce the activation loss in MFCs. Also, a Pt-coated anode was not favorable for the initial or long-term bacterial attachment due to its high hydrophobicity (contact angle = $124^{\circ}$), which promotes easy detachment of the biofilm from the anode surface. Maximum power ($655.0\;mW/m^2$) was obtained at a current density of $3,358.8\;mA/m^2$ in the MFCs with longer acclimation periods. It was found that a dense biofilm was able to enhance the charge transfer rates due to the complex development of a biofilm matrix anchoring the electrochemically active microorganisms together on the anode surface. Among the major components of the extracellular polymeric substance, carbohydrates ($85.7\;mg/m^2_{anode}$) and proteins ($81.0\;mg/m^2_{anode}$) in the dense anode biofilm accounted for 17 and 19%, respectively, which are greater than those in the sparse anode biofilm.