In today’s world, one of the most important problems of humanity is the energy. Due to irregular use of fossil fuels, the environment is getting polluted more and more. Therefore, it’s crucial to replace the fossil fuels with modern clean energies. Fuel cells are one of the most promising technologies that can be used with any electrical system. Polymer electrolyte membrane or proton exchange membrane (PEM) fuel cells are currently one of the most efficient systems designed to convert chemical energy of hydrogen and oxygen to electricity directly. These systems can be used anywhere from cars to power plants.
In polymer electrolyte membrane or proton exchange membrane (PEM) fuel cells, there is polymer membrane between two porous electrically conductive electrodes. The membrane side surfaces are covered with two thin catalyst layers. Compressed hydrogen is the main fuel used for these cells. The entering hydrogen, while facing to the anode electrode and the catalyst, will split to an electron and a hydrogen positive ion. The catalyst is usually made of platinum supported on carbon fiber. The hydrogen ions will diffuse to the membrane, reaching to the oxygen negative ions and produce water as the only byproduct. The electrons obtained from hydrogen ionization will travel through the anode electrode to an external circuit, then travel back to oxygen molecules through the porous cathode electrode and produce negative oxygen ions [1,2].
H2 → 2H+ + 2e– Anode reaction
½ O2 + 2H+ +2e– → H2O cathode reaction
As was mentioned before, cleanness is the key factor for future energy sources and the fuel cells seem to have this key factor beside the high efficiency, portability, and safety. Today, many car or other energy consuming device factories, have concentrated on the fuel cell and its usage on their systems. It’s reported by  that fuel cell technology will be the main energy production system by year 2100. this trend is shown in the following figure.
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