Hydrogen solid alkaline membrane fuel cell

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). 

There exist a variety of fuel cells. For practical reasons, fuel cells are classified by the type of electrolyte employed. The following names and abbreviations are frequently used in publications alkaline fuel cells (AFC), molten carbonate fuel cells (MCFC), phosphoric acid fuel cells (PAFC), solid oxide fuel cells (SOFC), and proton exchange membrane fuel cells (PEMFC). Among different types of fuel cells under development today, the PEMFC, also called polymer electrolyte membrane fuel cells (PEFC), is considered as a potential future power source due to its unique characteristics [1-3]. The PEMFC consists of an anode where hydrogen oxidation takes place, a cathode where oxygen reduction occurs, and an electrolyte membrane that permits the transfer of protons from anode to cathode. PEMFC operates at low temperature that allows rapid start-up. Furthermore, with the absence of corrosive cell constituents, the use of the exotic materials required in other fuel cell types is not required [4]. 

A single fuel cell is essentially an electrochemical sandwich, only a fraction of an inch thick, with a negatively charged anode on one side, a positively charged cathode on the other, and an electrolyte (a watery acidic or alkaline solution or a solid plastic membrane that permits the migration of electrically charged hydrogen atoms from the anode to the cathode) in the middle. Many individual cells can be stacked to produce a usable amount of electricity. 

Fuel cells are typically classified according to the types of the electrolytes they use. There are alkaline fuel cells (operating temperature -60-200 °C), phosphoric acid fuel cells ( 120-210 °C), molten carbonate fuel cells ( 650 °C), solid oxide fuel cells (-600-1000 °C), and proton-exchange membrane (PEM) fuel cells (RT-90 °C). A direct methanol fuel cell (DMFC) can be considered as a special type of the PEM fuel cell that uses methanol (in either vapor or liquid form) rather than hydrogen as the fuel. This review article focuses exclusively on PEM fuel cells. 

Vinodh, R. Purushothaman, M. Sangeetha, D., Novel quatemized polysulfone/ZiOj composite membranes for solid alkaline fuel cell applications. International Journal of Hydrogen Energy 2011,36(12), 7291-7302. 

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