Why is platinum used as a catalyst in many fuel cells?
The proton exchange membrane is one of the most advanced fuel cell designs. Hydrogen gas under pressure is forced through a catalyst, typically made of platinum, on the anode (negative) side of the fuel cell. At this catalyst, electrons are stripped from the hydrogen atoms and carried by an external electric circuit to the cathode (positive) side. The positively charged hydrogen ions (protons) then pass through the proton exchange membrane to the catalyst on the cathode side, where they react with oxygen and the electrons from the electric circuit to form water vapour (H2O) and heat. The electric circuit is used to do work, such as power a motor.
Platinum is used as a catalyst in fuel cells because it effectively facilitates the electrochemical reactions necessary to generate electricity. Specifically, it acts as an active layer on the anode to help separate electrons from hydrogen atoms, a critical step in the power-generation process.123
The use of platinum in this capacity is long-standing, dating back to the work of William Grove in 1839. While platinum is highly efficient for these reactions, it is a precious metal, and its high cost remains a significant challenge in making fuel cell technology commercially competitive. To address this, researchers often use a carbon base to support the platinum, which allows for the use of smaller quantities of the metal while maintaining the necessary catalytic activity.213