• Journal of Electrochemical Science and Technology
• /
• v.13 no.3
• /
• 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.

• Journal of Microbiology and Biotechnology
• /
• v.23 no.12
• /
• pp.1765-1773
• /
• 2013

The cathode reaction is one of the most seriously limiting factors in a microbial fuel cell (MFC). The critical dissolved oxygen (DO) concentration of a platinum-loaded graphite electrode was reported as 2.2 mg/l, about 10-fold higher than an aerobic bacterium. A series of MFCs were run with the cathode compartment inoculated with activated sludge (biotic) or not (abiotic) on platinum-loaded or bare graphite electrodes. At the beginning of the operation, the current values from MFCs with a biocathode and abiotic cathode were $2.3{\pm}0.1$ and $2.6{\pm}0.2mA$, respectively, at the air-saturated water supply in the cathode. The current from MFCs with an abiotic cathode did not change, but that of MFCs with a biotic cathode increased to 3.0 mA after 8 weeks. The coulomb efficiency was 59.6% in the MFCs with a biotic cathode, much higher than the value of 15.6% of the abiotic cathode. When the DO supply was reduced, the current from MFCs with an abiotic cathode decreased more sharply than in those with a biotic cathode. When the respiratory inhibitor azide was added to the catholyte, the current decreased in MFCs with a biotic cathode but did not change in MFCs with an abiotic cathode. The power density was higher in MFCs with a biotic cathode ($430W/m^3$ cathode compartment) than the abiotic cathode MFC ($257W/m^3$ cathode compartment). Electron microscopic observation revealed nanowire structures in biofilms that developed on both the anode and on the biocathode. These results show that an electron-consuming bacterial consortium can be used as a cathode catalyst to improve the cathode reaction.

• Journal of Soil and Groundwater Environment
• /
• v.18 no.1
• /
• pp.129-136
• /
• 2013

This research was conducted to investigate effects of acid buffering capacity and soil component in treatment of phenanthrene using electrokinetic-Fenton process. In Hadong clay of high acid buffering and low iron oxide content, it was difficult to oxidize phenanthrene due to shortage of iron catalyst and scavenger effect of carbonate minerals. The desorbed phenanthrene conductive to Fenton oxidation was transported toward cathode by electroosmotic flow. However, in Youngdong illitic clay, oxidation of phenanthrene near anode readily occurred compared to Hadong clay due to high iron content and low acid buffering capacity.

• Bulletin of the Korean Chemical Society
• /
• v.32 no.2
• /
• pp.571-575
• /
• 2011

Graphite-based electrodes were prepared using synthetic graphite (MCMB 1028) or natural graphite (NG) powder using a dimensionally stable anode (DSA) as a substrate. Their electrochemical properties were investigated in vanadiumbased electrolytes to determine how to increase the durability and improve the energy efficiency of redox flow batteries. Cyclic voltammetry (CV) was performed in the voltage range of -0.7 V to 1.6 V vs. SCE at various scan rates to analyze the vanadium redox reaction. The graphite-based electrodes showed a fast redox reaction and good reversibility in a highly concentrated acidic electrolyte. The increased electrochemical activity of the NG-based electrode for the $V^{4+}/V^{5+}$ redox reaction can be attributed to the increased surface concentration of functional groups from the addition of conductive material that served as a catalyst. Therefore, it is expected that this electrode can be used to increase the power density and energy density of redox flow batteries.

• Journal of the Korean Electrochemical Society
• /
• v.17 no.3
• /
• pp.179-186
• /
• 2014

Methanol electro oxidation on the surface of carbon paste modified by $NiCl_2/6H_2O$ was studied in 1M NaOH by potentiostatic and potentiodynamic methods. Ni/C catalyst by the concentration of 5% Ni showed about twice higher electro catalytic activity than Ni metal. The amount of monolayer's on the surface of electrode is almost one order higher for Ni/C than Ni electrode. The kinetic parameters and the diffusion coefficient of methanol were derived from chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) measurements.

• Journal of the Korean Ceramic Society
• /
• v.42 no.12 s.283
• /
• pp.860-864
• /
• 2005

In this study, we fabricated honeycomb type Mixed-Gas Fuel Cell (MGFC) which has advantages of stacking to the axial direction and increasing volume power density. Honeycomb-shaped anode with four channels was prepared by dry pressing method. Two alternative channels were coated with electrolyte and cathode slurry in order to make cathodic reaction sites and the others were filled with partial oxidation (POX) catalyst to increase fuel conversion. Furthermore we employed the sol-gel technique which can increase cell performance and decrease carbon coking.

• Proceedings of the KIPE Conference
• /
• 2017.07a
• /
• pp.461-462
• /
• 2017

가장 대표적인 연료전지인 고분자 전해질 연료전지(PEMFC; polymer electrolyte membrane fuel cell)은 두 개의 전극으로 이루어지며, 각 전극(electrode)에 공급되는 수소(anode)와 공기(cathode)의 원활한 반응을 위해 촉매(catalyst)로서 백금(Pt)을 사용한다. 이 때, 촉매의 실험 조건에 따라 연료전지 두 전극의 반응이 달라지므로 촉매의 가변성 즉, 가변적인 전극 조건에 따른 전기화학적 특성이 면밀히 분석되어야 한다. 그러므로, 본 논문에서는 촉매의 변화에 기인한 가변적인 전극 특성에 따른 연료전지의 전기화학적 특성 분석을 실시하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1999.11a
• /
• pp.617-620
• /
• 1999

To reduce the consumption of chemicals and ultra pure water(UPW) in cleaning process used in device manufacturing, we proposed wet processes that use electrolytic ionized water(EIW), which is generated by electrolysis of a diluted electrolyte solution or UPW and systemically investicate the EIW\`s characteristics. EIW\`s pH values are increased in cathode chamber and decreased in anode chamber according to the electrolysis time and its varied ratio is reduced with time increasement. The variation of pH and ORP is increased accordin to the applied voltage until critical voltage. But more than that voltage, the variation is decreased because of ion\`s scattering effect. When electrolyte is added, the effects of electrolysis is increased because electrolyte acts as catalyst. But when the density of electrolyte is increased more than critical value, ion\`s flowage is obstructed and the effects of electrolysis is decreased.

• Transactions of the Korean hydrogen and new energy society
• /
• v.31 no.6
• /
• pp.587-595
• /
• 2020

Nickel-based bimetallic catalysts were investigated for use in direct borohydride/hydrogen peroxide fuel cells. For anode and cathode, PdNi and AuNi catalysts were used, respectively. Nickel-based bimetallic catalysts have been investigated through various methods, such as inductively coupled plasma optical emission spectroscopy, transmission electron microscopy, scanning electron microscopy, and energy dispersive spectroscopy. The performance of the catalysts was evaluated through fuel cell tests. The maximum power density of the fuel cell with nickel-based bimetallic catalysts was found to be higher than that of the fuel cell with the monometallic catalysts. The nickel-based bimetallic catalysts also exhibited a stable performance up to 60 minutes.

• Journal of the Korean Applied Science and Technology
• /
• v.29 no.1
• /
• pp.102-107
• /
• 2012

The recovery of a Pt anode in a PEMFC through 30 ppm $H_2S/H_2$ exposure was evaluated by using a cyclic voltametry(CV) scan. First, the PEMFC unit cell performanc loss was measured three times under an anode feeding with 30 ppm $H_2S/H_2$ for 1hr at $0.5A/cm^2$ of current density. The initial cell performance was $1.16A/cm^2$ at 0.6 V without $H_2S$ poisoning. After first poisoning step for 1hr the cell performance was decrease to $0.77A/cm^2$, and the further poisoning steps decreased up 0.57 V. Finally, the recovery of the cell performance of $H_2S$ poisoned PEMFC was achieved up to 90.3% by applying CV scan. Moreover, we also found out that another possible approach for over 80% recovery of the cell performance of $H_2S$ poisoned anode Pt catalyst layer was to just inject fresh hydrogen into the anode feeding stream.