Hydrogen-Oxygen Fuel Cell
Definition and meaning of Hydrogen-Oxygen Fuel Cell in chemistry.
A hydrogen-oxygen fuel cell is an electrochemical device that combines hydrogen and oxygen gas to generate electricity directly, producing water and heat as the only products.
In more detail
Hydrogen gas is oxidized at the anode, releasing electrons that travel through an external circuit to do electrical work, while oxygen is reduced at the cathode. The two electrodes are separated by an electrolyte (a proton-exchange membrane in PEM cells, or aqueous KOH in alkaline cells) that allows ions to cross while forcing electrons through the circuit. Because the reaction is a controlled redox process rather than combustion, it converts chemical energy to electrical energy with high efficiency and no direct carbon dioxide emissions. This makes hydrogen-oxygen fuel cells valuable for spacecraft power, fuel-cell electric vehicles, and backup power systems.
Key facts
| Overall reaction | 2H2 + O2 → 2H2O |
|---|---|
| Standard cell potential | E°cell ≈ 1.23 V |
| Byproducts | Water and heat (no combustion) |
| Field | Physical Chemistry |
In a proton-exchange membrane (PEM) fuel cell, the anode half-reaction is 2H2 -> 4H+ + 4e-, the cathode half-reaction is O2 + 4H+ + 4e- -> 2H2O, and the overall cell reaction is 2H2(g) + O2(g) -> 2H2O(l), with a standard cell potential of about 1.23 V.
Frequently asked questions
Is a hydrogen-oxygen fuel cell the same as burning hydrogen?
No. Combustion releases energy as heat and light through an uncontrolled radical chain reaction, while a fuel cell separates the oxidation and reduction half-reactions across an electrolyte so the electron transfer flows as usable electric current.
Why were hydrogen-oxygen fuel cells used on Apollo and Space Shuttle missions?
They provided reliable, efficient onboard electricity, and the water produced as a byproduct was purified and used as drinking water for astronauts.