H2 and anode:
Hydrogen fuel (H2) is channeled to the anode, where the catalyst separates the hydrogen's negatively charged electrons from the positively charged protons.
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PEM:
The membrane allows the positively charged protons to pass through to the cathode, but not the negatively charged electrons.

The negatively charged electrons must flow around the membrane through an external circuit. This flow of electrons forms an electrical current.
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Cathode:
At the cathode, the negatively charged electrons and positively charged hydrogen ions (protons) combine with oxygen to form water (H20) and heat.
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