Fuel Cell

Summary: A fuel cell is an electrochemical device that converts the chemical energy of a fuel (usually H₂) directly into electrical energy. Unlike batteries, fuel cells do not run down as long as fuel and oxygen are supplied. Tags: igcse chemistry fuel-cell electrochemistry energy keyword Created: 2026-07-14 Last Updated: 2026-07-14

Definition

A fuel cell converts chemical energy directly into electrical energy via redox reactions at two electrodes, with fuel (H₂) and oxidant (O₂) supplied continuously from external sources. The only waste product from a hydrogen fuel cell is water.

Hydrogen-Oxygen Fuel Cell

Overall reaction: 2H₂(g) + O₂(g) → 2H₂O(l)

• Anode (−): H₂ + 2OH⁻ → 2H₂O + 2e⁻ (oxidation)
• Cathode (+): O₂ + 2H₂O + 4e⁻ → 4OH⁻ (reduction)
• Contains a platinum catalyst on porous electrodes
• Electrolyte: KOH(aq) or proton-exchange membrane

Key Advantage Over Batteries

Fuel cells do not run down — they produce electricity continuously as long as fuel (H₂) and oxygen (O₂ from air) are supplied. Batteries have a finite amount of stored chemicals and eventually go flat.

See Also

• Fuel Cells — Full topic page
• Electrolysis Applications — Hydrogen production by electrolysis
• Redox Reactions — Oxidation and reduction
• Half Equation — Electrode half equations
• IGCSE-Chem-Index