What roles do the anode and cathode play in a hydrogen fuel cell?
The proton exchange membrane is one of the most advanced fuel cell designs. Hydrogen gas under pressure is forced through a catalyst, typically made of platinum, on the anode (negative) side of the fuel cell. At this catalyst, electrons are stripped from the hydrogen atoms and carried by an external electric circuit to the cathode (positive) side. The positively charged hydrogen ions (protons) then pass through the proton exchange membrane to the catalyst on the cathode side, where they react with oxygen and the electrons from the electric circuit to form water vapour (H2O) and heat. The electric circuit is used to do work, such as power a motor.
In a hydrogen fuel cell, the anode and cathode serve as the two essential electrodes that facilitate the conversion of chemical energy into electricity.12
- Anode: Hydrogen fuel is supplied to the anode, where it undergoes oxidation. During this process, the anode acts as the source of electrons, separating them from the hydrogen atoms to produce hydrogen ions and electrons.12
- Cathode: An oxidizer, such as oxygen, is supplied to the cathode. The cathode functions by absorbing electrons from the external circuit. Here, the hydrogen ions that migrated from the anode through the electrolyte combine with these electrons and the oxygen to produce water.12
By separating these oxidation and reduction reactions at distinct electrodes, the fuel cell creates an electromotive force that drives an electric current through an external circuit.12