Polymer electrolyte fuel cells alternatives

The conversion of hydrocarbon to hydrogen will play an important role in 21st century, especially, for providing hydrogen for polymer electrolyte fuel cell (PEFC). Currently, steam reforming of hydrocarbons, especially of CH4 (1), is the largest and generally the most economical way to make Hz. Alternative industrial chemical approach includes CH4 + HzO = CO H- 3Hz (1)... 

Ahluwalia R K and Wang X (2006), Rapid self-start of polymer electrolyte fuel cell stacks from subfreezing temperatures. Journal of Power Sources, 162,502-512. Ajanovic A (2008), On the economics of hydrogen from renewable energysources as an alternative fuel in transport sector in Austria, International Journal of Hydrogen Energy, 33,4223- 234. 

Sasaki K, Takasaki F, Noda Z, Hayashi S, Shiratori Y, Ito K (2010) Alternative electrocatalyst support materials for polymer electrolyte fuel cells. ECS Trans 33(1) 473 82... 

Abstract During the last two decades, extensive efforts have been made to develop alternative hydrocarbon-based polymer electrolyte membranes to overcome the drawbacks of the current widely used perfluorosulfonic acid Nafion. This chapter presents an overview of the synthesis, chemical properties, and polymer electrolyte fuel cell applications of new proton-conducting polymer electrolyte membranes based on sulfonated poly(arylene ether ether ketone) polymers and copolymers. 

Sahu, A.K., Selvarani, G., Pitchumani, S Sridhar, P and Shukla, A.K. (2007) A sol-gel modified alternative Nafion-silica composite membrane for polymer electrolyte fuel cells. /. Electrochim. Soa, 154 (2), B123-B132. 

Liquid-fuelled solid-polymer-electrolyte fuel cells are very promising as electrochemical power sources and have drawn immense attention as high-effidency and low-emission power sources, for application in portable devices and automotive ap>phcations (Li, 2006). Fuel cells are an alternative power sources that could be a future substitutes of the hydrocarbons as energy source. 

PEM fuel cells use a solid proton-conducting polymer as the electrolyte at 50-125 °C. The cathode catalysts are based on Pt alone, but because of the required tolerance to CO a combination of Pt and Ru is preferred for the anode [8]. For low-temperature (80 °C) polymer membrane fuel cells (PEMFC) colloidal Pt/Ru catalysts are currently under broad investigation. These have also been proposed for use in the direct methanol fuel cells (DMFC) or in PEMFC, which are fed with CO-contaminated hydrogen produced in on-board methanol reformers. The ultimate dispersion state of the metals is essential for CO-tolerant PEMFC, and truly alloyed Pt/Ru colloid particles of less than 2-nm size seem to fulfill these requirements [4a,b,d,8a,c,66j. Alternatively, bimetallic Pt/Ru PEM catalysts have been developed for the same purpose, where nonalloyed Pt nanoparticles <2nm and Ru particles <1 nm are dispersed on the carbon support [8c]. From the results it can be concluded that a Pt/Ru interface is essential for the CO tolerance of the catalyst regardless of whether the precious metals are alloyed. For the manufacture of DMFC catalysts, in... 

In the past two decades, fuel cells and in particular imi-exchange membranes have become a top priority topic in material research. Fuel cells are seen as promising alternative energy conversion systems replacing the combustion-based techniques. Among the various types of fuel cells, the low-temperature fuel cells like the polymer electrolyte membrane fuel cell (PEMFQ, DMFC, or alkaline fuel cell (AFC) are the most flexible ones concerning range of appUcations e.g. portable, automotive, and stationary. 

The best catalysts for the electrochemical oxidation and production of hydrogen are platinum metal and the hydrogenase enzymes. Both catalyze the reaction of two protons with two electrons to form H2, as shown in Equation 7.1. Because of its superior catalytic rates and overpotentials compared to other metals and because of its high stabihty compared to hydrogenase enzymes, platinum is currently used as the catalyst for both half reactions (the oxidation of H2 and the reduction of O2) in polymer electrolyte membrane (PEM) fuel cells, which have been proposed for automotive transportation [1]. However, the high cost of platinum provides a strong impetus for developing less expensive alternatives. 

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