Proton membrane development

DMFCs and direct ethanol fuel cells (DEFCs) are based on the proton exchange membrane fuel cell (PEM FC), where hydrogen is replaced by the alcohol, so that both the principles of the PEMFC and the direct alcohol fuel cell (DAFC), in which the alcohol reacts directly at the fuel cell anode without any reforming process, will be discussed in this chapter. Then, because of the low operating temperatures of these fuel cells working in an acidic environment (due to the protonic membrane), the activation of the alcohol oxidation by convenient catalysts (usually containing platinum) is still a severe problem, which will be discussed in the context of electrocatalysis. One way to overcome this problem is to use an alkaline membrane (conducting, e.g., by the hydroxyl anion, OH ), in which medium the kinetics of the electrochemical reactions involved are faster than in an acidic medium, and then to develop the solid alkaline membrane fuel cell (SAMFC). 

PEM ED - To develop thermally stable protonic membranes based on sulfonated polymers and hybrid inorganic-organic systems that can be produced on an industrial scale. 

The proton exchange membrane has to be improved so as to reduce resistance across the membrane and the transfer of sulphur species across the membrane that results in the deposition of sulphur on the cathode thereby poisoning the cathode. The focus will initially be on testing membranes developed for fuel cells. The NWU will be acquiring and testing fuel cell membranes which include the three top membranes in meeting the minimum requirements as set by US DOE for 2008, from Professor P. Pintauro (Vanderbilt University, Nashville, USA), Dr. R. Wycisk (Case Western Reserve University, Cleveland, USA) and Giner Electrochemical Systems Inc. 

Over the last few years, membrane development has intensified and numerous new developments have been reported [10]. This increase in the interest in novel proton-conducting membranes for fuel cell applications has resulted in several studies and review publications on the overall subject and also on some related topics (e.g., nonfluorinated membranes). The content of these reviews has been used and is cited in the appropriate sections. 

At this point, we do not know which of several approaches is most promising. Thus, our membrane development efforts involve (1) a full-fledged effort to explore approaches involving polymer synthesis and development, as well as implementation of new carrier media to replace the function of water in Nafion, and (2) a study of proton transfer dynamics. We are using theoretical approaches to explore specific possibilities for new acid group types or for... 

One of the more challenging locations, therefore, for consideration of the comprehensive hydrophobic effect in the panoply of biological energy conversions is the electron transport chain embedded within the inner mitochondrial membrane. Essential parts of these protein-based machines insert into and function in very hydrophobic lipid bilayers. Here the ingress and egress of protons for develop-... 

In situ NMR Investigation of electrocatalytic mechanism and degradation mechanism of proton exchange membranes, development of electrocatalysts h, H, Pt... 

In addition improvements in the sulfonated perfluorinated membranes, or development of new protonic membranes with reduced alcohol cross-over and better conductivity and stability at higher temperatures (up to 200 °C) are stiU challenging topics before any commercialization of DAFC systems. 

Use of sulfonated polymers as the proton-conductive component in the fuel cell membranes at T < 100°C Use of nonfluorinated ionomers physical and/or chemical cross-linking of the fuel cell membranes Use of nonfluorinated ionomers physical and/or chemical cross-linking of the fuel cell membranes Development of organic-inorganic composite membranes, based on our cross-linked ionomer membrane systems, in which the inorganic membrane component serves as water storage or even contributes to H -conduction Use of commercially available polymers for chemical modification and membrane formation, which avoids expensive development of novel polymers... 

In recent times, there has been considerable research effort to develop PEM membrane for higher operating temperature range. Membrane development effort is primarily concentrated on the development of high-temperature membrane with operation at 120°C or higher, lower relative humidity with less than 10% for operation at 80°C, higher proton conductivity, and a thinner membrane for reduced ohmic loss and improved tolerance for impurities like carbon monoxide. 

CFq-CFj is known to undergo a reversible activation of catalytic activity when a difference in the electrochemical potential of protons (AyH ) develops across the thylakoid membrane (Schlodder et al.,1982). This phenomenon may be es lained by a model based on a dual pH optimum requirement of CFq-CFj (Mitchell,1981). The model assumes the following ... 

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