A fuel cell is primarily used to provide electricity from chemical reactions. It uses the chemical energy of hydrogen and oxygen to generate electricity without combustion. One of the basic types of fuel cells is the polymer electrolyte membrane fuel cell (PEMFC). This section will provide a general description of its parts, how they work, and the material they are made of.3.2 BackgroundPolymer electrolyte membrane fuel cells operate at relatively low temperatures, around 80°C (176°F). Low temperature operation allows them to start quickly (less warm-up time) and results in less wear on system components, resulting in better life. However, a noble metal catalyst (typically platinum) must be used to separate the hydrogen's electrons and protons, adding cost to the system. PEM fuel cells are mainly used for transportation applications and some stationary applications. Due to their fast startup time, low orientation sensitivity and favorable power-to-weight ratio, PEM fuel cells are particularly suitable for use in passenger vehicles, such as cars and buses. A significant barrier to using these fuel cells in vehicles is hydrogen storage. Most fuel cell vehicles (FCVs) powered by pure hydrogen must store the hydrogen on board as compressed gas in tanks. Due to hydrogen's low energy density, it is difficult to store enough hydrogen on board to allow vehicles to travel the same distance as gasoline-powered vehicles before refueling. This increases costs and maintenance. They provide high power density and offer the advantages of reduced weight and volume compared to other fuel cells. 3.3 PEMFC StructurePEMFC Figure- 1 Polymer ...... in the center of the paper ...... for the fuel cell. [Lister & McLean]• Electrolyte membrane: Electrolyte membrane is usually made of Nafion due to its availability, low cost, low permeability, good chemical stability and strength. However, it is expensive. [Lister & McLean]• Catalyst: The most widely used catalyst for PEM fuel cells is platinum. Platinum catalytic layers are rough and porous to provide a larger surface area for oxygen and hydrogen to react with Pt. They can also be particles. [Wang 2011]• Current collectors, GDLs and bipolar plates: Current collectors are made of graphitic materials due to its good conduction. The GDL gas diffusion layers are made of carbon paper, which has low electronic resistance to provide maximum electronic contact and prevent water flooding. The bipolar plates are made of graphite thermosetting materials. [Lister and McLean ]