The Proton-Exchange Membrane Fuel Cell PEMFC

The Proton-Exchange Membrane Fuel Cell (PEMFC) 

Typically, carbon electrodes with a platinum electrocatalyst are used for both the anode and cathode. The PEM used in the fuel cell serves to keep the fuel separate from the oxidant, and also as an electrolyte. 

Another issue for PEMFCs is that of water management. Whereas, dehydration of the membrane leads to a reduction in proton conductivity, an excess of water may lead to the electrode being flooded. 

An additional, but critical, disadvantage of PEMFCs is their high cost, this being associated primarily with the platinum catalyst and fluorinated polymer electrolyte membrane. 

A fuel cell is a layered structure consisting of an anode, a cathode, and a solid electrolyte (Fig. 8.31). Hydrogen reacts on the anode, typically Pt or Pt/Ru nano-particles deposited on a conducting graphite support, where it is oxidized into protons and electrons  

The electrons are transported through an outer circuit connected to the cathode, where oxygen is reduced to oxygen ions on a similar catalyst system as for the anode  

Since the electrolyte membrane only allows the conduction of ions, the electrons are forced through an exterior circuit, creating an electromotive force. The voltage generated by such a cell is given by the Nernst equation. For the hydrogen-oxygen reaction we can write  

Since two electrons pass through the circuit per water molecule generated and AG is given per mole, the potential is found by dividing AG by the charge associated with one mole of water, 

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The most promising fuel cell for transportation purposes was initially developed in the 1960s and is called the proton-exchange membrane fuel cell (PEMFC). Compared with the PAFC, it has much greater power density state-of-the-art PEMFC stacks can produce in excess of 1 kWA. It is also potentially less expensive and, because it uses a thin solid polymer electrolyte sheet, it has relatively few sealing and corrosion issues and no problems associated tvith electrolyte dilution by the product water. 

Would the preferential CO oxidation reaction be needed if the proton-exchange membrane fuel cell (PEMFC) with Pt anode catalyst were able to work at temperatures higher than about 403 K ... 

Gamburzev, S., and Appleby, A. J. Recent progress in performance improvement of the proton exchange membrane fuel cell (PEMFC). Journal of Power Sources 2002 107 5-12. 

Because of its lower temperature and special polymer electrolyte membrane, the proton exchange membrane fuel cell (PEMFC) is well-suited for transportation, portable, and micro fuel cell applications. But the performance of these fuel cells critically depends on the materials used for the various cell components. Durability, water management, and reducing catalyst poisoning are important factors when selecting PEMFC materials. 

After rehearsing the working principles and presenting the different kinds of fuel cells, the proton exchange membrane fuel cell (PEMFC), which can operate from ambient temperature to 70-80 °C, and the direct ethanol fuel cell (DEFC), which has to work at higher temperatures (up to 120-150 °C) to improve its electric performance, will be particularly discussed. Finally, the solid alkaline membrane fuel cell (SAMFC) will be presented in more detail, including the electrochemical reactions involved. 

Proton Exchange Membrane Fuel Cells (PEMFCs) The proton exchange membrane fuel cells (PEMFCs) are also... 

Molecular hydrogen in the gaseous state has been used widely as a chemical resource and is now becoming a significantly important energy source, especially as the fuel source for the Proton Exchange Membrane Fuel Cell (PEMFC). 

Engineering applications such as hydrogen storage in metal hydrides, the nickel-metal hydride rechargeable battery (Ni-MH), and the proton exchange membrane fuel cell (PEMFC) are basically dependent on the surface properties and characteristics. 

The proton exchange membrane fuel cell (PEMFC) has been extensively studied in the last two decades for many applications and especially for low emissions vehicles.Pure hydrogen is the ideal fuel for the PEMFC. However, it cannot be stored practically in sufficient quantities on-board a vehicle and, therefore, there is a need for an adequate supply infrastructure. On-board H2 production from liquid fuel such as methanol is considered as a promising method for fuel cell vehicle application. Hydrogen-rich reformed gas presents 1-2% of CO. Unfortunately, this CO concentration cannot be tolerated by the PEMFC electrodes at low operating temperature. In order to avoid... 

Since the proton exchange membrane fuel cell (PEMFC) anode catalyst can be poisoned by CO at ppm levels of concentration, it is necessary to estimate how much CO will exist at each of the fuel processing steps. Let us use the steam reforming As an example to do some analyses. Table 3.2 lists the molar Gibbs free energy of formation of the species involved, plus values for CO2 and O2 for later analysis. 

Carbon materials, such as carbon cloth and carbon paper, are also good substrates for the deposition of photocatalysts, due to their low resistivity and cost. They are also widely used in the proton exchange membrane fuel cell (PEMFC), and are also commercially available at www.fuelcellstore.com. Carbon cloth/paper is supplied with an untreated surface or reinforced with PTFE. Since the photocatal5ftic reactions at the anode side involve three phases liquid electrol)4e, solid anode photocatalyst, and the produced gaseous CO2, carbon materials with hydrophilic surfaces are preferred in the fabrication of photoanodes. Compared to the previous two substrates, carbon material can be used directly without any pretreatment. 

The proton exchange membrane fuel cell (PEMFC), also called the solid polymer fuel cell (SPFC), was first developed by General Electric in the United States in the 1960s for use by NASA on their first manned space vehicles. 

Now that technologies to use hydrogen as a clean fuel are readily available, like the Proton Exchange Membrane Fuel Cell (PEMFC), and can be developed at an industrial scale, research mainly focuses on the barrier of development which is hydrogen storage for delayed use. In fact, if nowadays the H2 production methods are well known and controlled, the storage and transportation of the fuel remain major obstacles to its use [3]. 

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