http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
대체에너지 분야에서의 촉매기술 심포지엄 3 : F-42
( Scibioh M. Aulice ),하흥용 한국화학공학회 2007 화학공학의이론과응용 Vol.10 No.2
Much of the performance still to be gained in proton exchange membrane fuel cells (PEMFCs) and direct methanol fuel cells (DMFCs) in use today is available from improvements to the cathode, traditionally made from unsupported or carbon supported platinum. This presentation is aiming not at the mere updation of the work in the field of cathode catalysts in low temperature fuel cells, but to critically address some of the vital issues in their development particularly with respect to formulation, design and fabrication of cathode materials. The current loadings of noble metals need to be reduced. In order to reduce the usage of precious metals and thus cost, the best possible performance has to be extracted from a given amount of the catalyst. It is worth emphasizing on the areas where improvements would be highly advantageous.
D-33 : Modification of carbon support to improve catalyst utilization for DMFC
박찬희,이재영,( Scibioh M Aulice ),오인환,홍성안,하흥용 한국화학공학회 2007 화학공학의이론과응용 Vol.10 No.2
Carbon supported and unsupported Pt-Ru alloys are currently considered as the best electrocatalysts for methanol oxidation in direct methanol fuel cells (DMFCs). Significant efforts have been made to find appropriate synthesis procedure for production of these catalysts with suitable dispersions. Major attempts were focused on lowering the amount of catalyst loading in the electrodes. The platinum utilization even in the best performing electrodes remained very low (10-25%). The main requirement of a good electrode is a three-phase boundary, between the supply of reactants on one hand and the catalyst particle and the ionic conductor on the other hand. In this work, the carbon supported Pt-Ru catalyst was prepared by using a modified carbon fine powder as support to extent the reaction area of three-phase boundary and to increase the utilization of catalyst particulates. The prepared catalysts were characterized by using BET surface area and pore size distribution measurements, XRD, TEM, SEM, CV techniques and DMFC single cell tests. Compared to commercial catalysts, the home-made 40 wt.% Pt-Ru supported on modified carbon support exhibited the highest cell performance in DMFC. The results will be discussed in the light of comprehensive data.
Investigations of performance degradation and mitigation strategies in direct methanol fuel cells
Park, J.Y.,Scibioh, M.A.,Kim, S.K.,Kim, H.J.,Oh, I.H.,Lee, T.G.,Ha, H.Y. Pergamon Press ; Elsevier Science Ltd 2009 International journal of hydrogen energy Vol.34 No.4
This paper addresses a gradual performance loss that is encountered in a direct methanol fuel cell (DMFC) when it is subjected to a continuous operation at constant-load conditions for a period of 600h. To gain insights into the physico-chemical origins of the degradation process, various analytical techniques are employed and characterization of the membrane electrode assembly (MEA) is carried out before and after the lifetime test. The results reveal that the performance degradation of MEA mainly stems from the degradations at the cathode, and this is further confirmed by individual impedance analyses of cathode and anode as well as by the observation on finding increased quantity of methanol exiting from the cathode with increased operational time. Supplement experiments with the cathodes containing either pre-oxidized Pt catalyst or a fractional amount of Ru catalyst offer new clues to understand the deactivation mechanism. The hydrophobicity losses of gas diffusion layers are prominent in the outlet regions compared to the inlet regions of the DMFC assembly. Further, a couple of restoration techniques are employed to evaluate performance recovery. A periodical on-off switching of applied load and an air-break technique are found to be effective to restore the performance loss that occurs during fuel cell operations.