Science Buddies: "Ask an Expert"

Hello,

My project this year is titled "The Effect of Different Catalysts on the Efficiency/Electrical Output of a Polymer Exchange Membrane (PEM) Fuel Cell". I am starting my research and I am confused about the role of platinum catalyst in fuel cells.

In a hydrogen fuel cell, the reaction goes like this: At the cathode, the hydrogen is split into protons and electrons. The protons cross the proton exchange membrane to reach the oxygen molecules. The electrons take a different path (though an external circuit) and rejoin with oxygen and protons to form water. Does the platinum break apart the hydrogen into protons and electrons at the beginning of the reaction, or does it catalzye the reaction of the protons, electrons, and oxygen into water at the end of the reaction?

Hello and welcome to the forums!

You've asked an interesting question, one that has more than one answer. However, for a Proton Exchange Membrane fuel cell, I think Wikipedia has the simplest answer:http://en.wikipedia.org/wiki/Fuel_cell

The anode catalyst breaks down the fuel into electrons and ions. The anode catalyst is usually made up of very fine platinum powder.
The cathode catalyst turns the ions into the waste chemicals like water or carbon dioxide.

It sounds like the answer to your question is that the catalyst does both things, working at both electrodes. Other types of fuel cells use catalysts differently, so I think you should research all the different types of fuel cells for your report. Good luck!
Keith