*1.6.6. SOFC*

*1.6.4. PAFC*

makes it uneconomical.

238 Electrodeposition of Composite Materials

*1.6.5. PEMFC*

on system components).

des.

"PAFC" uses liquid phosphoric acid as an electrolyte contained in a silicon carbide matrix bonded in Teflon and has finely dispersed platinum catalyst inside its porous carbon electro‐

Phosphoric acid fuel cell is considered as the first-generation modern fuel cells. It is the first most commercially developed fuel cell used to power many commercial premises and large buses such as city buses. The major challenge of PAFC is the costly platinum catalyst which

**Figure 7.** Showing components of phosphorus acid fuel cell (www.fuelcellmarkets.com)

ruthenium catalysts that are more resistant to CO, as better substitutes.

"PEMFC" uses a solid polymeric membrane as the electrolyte and platinum catalyst contained in porous carbon electrodes. Polymer electrolyte membrane fuel cells[2,4& 12]operate at moderately low temperature range of 80°C to 100°C. The low operating temperature range enables them to quick start (short warm-up time) and results in better durability (lesser wear

PEMFC utilizes the platinum catalyst on its membrane. Platinum catalyst[7]is very expensive even in small quantity and also very sensitive to carbon monoxide poisoning, making application of reactor that will reduce its concentration in hydrogen fuel gas-derived fossil fuel necessary. This adds to the overall cost. In recent times, researchers are exploring platinum/ "SOFC" uses a hard, nonporous solid ceramic compound as the electrolyte, such as zirconium oxide stabilized with yttrium oxide, instead of a liquid. It works at a higher temperature range of 800° C to 1000°C and can attain efficiencies around 60%. This makes it suitable for providing auxiliary power in vehicles and also for industrial electricity and heat generation. The hightemperature operating conditions allow fuels to reform internally and also nullify the need for any precious metal catalyst, thereby saving cost. The high operating temperature results in a slow start-up and requires huge thermal shielding which renders it unsuitable for transpor‐ tation and small portable applications. The development of moderate cost materials that will be stable under the stringent operating conditions is the major challenge facing this technology. Research and development are currently developing lower-temperature SOFCs operating at or below 800°C with minimal durability problems and lesser cost.

**Figure 9.** Showing components of molten carbon fuel cell (www.iit.edu)
