Proton exchange membrane fuel cell electrochemical reaction

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). 

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. 

Camara, G.A. et al.. The CO poisoning mechanism of the hydrogen oxidation reaction in proton exchange membrane fuel cells, J. Electrochem. Soc., 149, A748, 2002. 

The transport of energy, mass, and charge is at the heart of proton exchange membrane fuel cell (PEMFC) operation. The porous layers in modern membrane electrode assemblies (MEAs) lie at the Interface between the macroscopic phenomena occurring in the flow channels and the micro- and nanoscopic processes in the catalyst layers (see Figure 5.1). These layers must deliver the reactants and remove the products from the electrochemical reactions at the fuel cell electrodes. They must also provide connections to the current collecting plates with minimal thermal and electrical resistances. 

Fig. 11 A proton exchange membrane fuel cell experiencing Hj/air front start/stop, showing the major electrochemical reactions considered during start/stop operations. ORR Oxygen reduction reaction, COR Carbon oxidation reaction, OER Oxygen evolution reaction, and HOR Hydrogen oxidation reaction...

Fuel cells are electrochemical cells where the chemical energy of the fuel was converted into electricity for power generation with high efficiency [1,2]. Industrial purified hydrogen and air are often used in fuel cells to eliminate any pollution or emission, which is known as proton exchange membrane fuel cells (PEMFCs). In a typical PEMFC, a steam of hydrogen is deUvered to the anode side of the membrane electrode assembly (MEA) [3,4], At the anode, it is catalyzed by platinum (Pt) and split into protons and electrons. This oxidation half-cell reaction is represented as follows ... 

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