A Proton Exchange Membrane (PEM) fuel cell consists of a proton-conducting membrane between two electrodes: the anode and the cathode. Hydrogen gas is supplied to the anode, and oxygen from the air is directed to the cathode. At the anode, hydrogen molecules split into protons and electrons with the help of a catalyst, usually platinum. The membrane allows only the protons to pass through to the cathode, while the electrons travel through an external circuit, generating electricity. At the cathode, protons, electrons, and oxygen combine to form water. This reaction, also facilitated by a catalyst, produces water and heat as by-products. The overall reaction in a PEM fuel cell is simple: hydrogen and oxygen react to produce water, heat, and electricity. This process is clean and efficient, making PEM fuel cells a great choice for applications like powering vehicles and providing backup power for buildings, all while producing no harmful emissions.