In a PEM fuel cell, hydrogen gas is fed to the anode side where it is catalytically split into protons and electrons. The protons pass through the PEM to the cathode, while the electrons are forced through an external circuit, generating electricity. At the cathode, the protons, electrons, and oxygen gas combine to form water. This process is facilitated by catalysts at both the anode and cathode, typically made from platinum or platinum alloys.
