Electrons in a hydrogen fuel cell move through an external circuit because they cannot pass through the membrane.
Here's a breakdown of the electron flow in a hydrogen fuel cell:
- Hydrogen Input: Hydrogen fuel enters the anode side of the fuel cell.
- Separation at the Anode: At the anode, a catalyst separates hydrogen molecules into protons (H+) and electrons (e-).
- Proton Movement: The positively charged protons (H+) pass through a special membrane to the cathode. This membrane is specifically designed to allow only protons to pass.
- Electron Detour: The negatively charged electrons (e-) cannot pass through the membrane. According to the provided reference, "The membrane allows the positively charged protons to pass through to the cathode, but not the negatively charged electrons."
- External Circuit Flow: Instead, the electrons flow around the membrane through an external circuit. This external circuit connects the anode and cathode.
- Electrical Current: This flow of electrons forms an electrical current, which can be used to power devices.
- Arrival at the Cathode: The electrons eventually arrive at the cathode side of the fuel cell.
- Recombination: At the cathode, the electrons, protons, and oxygen from the air combine to form water (H2O).
In summary, because the membrane is impermeable to electrons, they are forced to take an alternate path via an external circuit, thereby generating electricity.
