What Is a Proton Exchange Membrane Fuel Cell

Fuel Cells are electrochemical devices that converts chemical energy into electricity. A PEM Fuel Cell (Proton Exchange Membrane fuel cell), also known as Proton Electrolyte Membrane fuel cell is an electrochemical device that uses a solid polymer membrane (PEM) to generate electricity by combining hydrogen and oxygen. This solid polymer membrane allows protons to pass through while blocking electrons.

Proton Exchange membrane fuel cells are one of the most widely used fuel cells especially for stationary power generation, automotive and academic application due to their low temperature operation.

How Does a PEM Fuel Cell Work

In a PEM fuel cell (Proton Electrolyte Membrane-based fuel cell), hydrogen gas is supplied at the anode and a chemical reaction occurs between hydrogen and a catalyst to produce a hydrogen ion and a free electron. The hydrogen ion diffused through the membrane to the cathode while the electron flows through a circuit to generate current and then combines to form water and heat as the only byproducts.

Overall reaction:

2H₂(g) + O₂(g) → 2H₂O(l)

Anode (Oxidation): Hydrogen gas loses electrons (is oxidized).

H₂(g) → 2H⁺(aq) + 2e⁻ (Acidic Medium)

Cathode (Reduction): Oxygen gas gains electrons (is reduced).

½O₂(g) + 2H⁺(aq) + 2e⁻ → H₂O(l) (Acidic Medium)

The overall process is called a redox reaction where simultaneous oxidation- loss of electrons at the anode and reduction - gain of electrons at the cathode occurs. These reactions are generally slow, so there is a need for catalysts such as platinum to speed up the reaction to give up electrical energy with water and heat as the by-product.