How Electrolyzers Work
At the cathode, the hydrogen ions that pass through the electrolyte combine with electrons to form hydrogen gas molecules.
In a PEM electrolysis stack, the function of the polymer electrolyte is to allow only the hydrogen ions to pass through it to the cathode. The membrane also serves as a physical barrier to prevent mixing of the hydrogen and oxygen gas products.
At the anode, water is split to hydrogen ions that pass through the cell membrane and oxygen ions that combine at the catalyst to form oxygen gas.
Electrons combine with hydrogen ions to generate the gaseous hydrogen product.