1. Hydrogen and Oxygen Supply:
- Hydrogen (H2) is supplied to the anode of the fuel cell, while oxygen (O2) is supplied to the cathode. These gases are usually supplied by external tanks or reformers that extract hydrogen from fuels such as natural gas or methanol.
2. Anode Reaction (Hydrogen Oxidation):
- At the anode, hydrogen molecules are split into protons (H+) and electrons (e-). This reaction is catalyzed by a catalyst, typically made of platinum or a platinum-based alloy.
- The chemical reaction at the anode is:
2H2 → 4H+ + 4e-
3. Proton Exchange Membrane (PEM):
- Between the anode and cathode is a Proton Exchange Membrane (PEM). The PEM is a solid electrolyte that allows protons to pass through but blocks the flow of electrons.
4. Cathode Reaction (Oxygen Reduction):
- At the cathode, oxygen molecules combine with protons and electrons to form water (H2O). This reaction is also catalyzed by a catalyst, usually made of platinum or a platinum-based alloy.
- The chemical reaction at the cathode is:
O2 + 4H+ + 4e- → 2H2O
5. Electrical Circuit:
- Electrons produced at the anode flow through an external circuit, creating an electric current. The flow of electrons is directed to power devices or charge batteries.
6. Water and Heat Production:
- As a byproduct of the reactions at the anode and cathode, water is produced. Additionally, some heat is also generated as a result of the electrochemical reactions in the fuel cell.
The overall reaction in a hydrogen fuel cell can be represented as:
2H2 + O2 → 2H2O + Heat + Electrical Energy
Hydrogen fuel cells operate continuously as long as there is a supply of hydrogen and oxygen. They produce electricity through electrochemical reactions, with water and heat as the primary byproducts. The efficiency of hydrogen fuel cells can be quite high, making them a promising technology for various applications, including transportation, power generation, and portable devices.
