Reading about PEM Fuel Cells, first on Wikipedia then on some other sites, I notice they talk a lot about the problem of CO poisoning. But almost always it's explicitly referred to as a problem in fuel supply, not oxidizer.
In fact, some reports show that govt agencies have actually tested these things in school busses with lifetimes of about 1200 hours. So if they get the oxygen from ambient air, and driving around normal urban environments, then it appears that CO through the air does not cause a problem.
My question is, how?
Here is a diagram from wikipedia too: https://upload.wikimedia.org/wikipedia/commons/a/a2/Membrane_Electrode_Assembly_-_Electro-Chemical_Reaction_Diagram.jpg
(Pic uploader not working on that link for some reason)
The diagram shows the catalyst on both sides. It is facing the oxygen input as well as the hydrogen input.
How is this possible? How is CO poisoning in the fuel side possible, but CO poisoning on the O side impossible? It is all using the same catalyst as far as I can tell, a Platinum-Rhuthenium alloy. Is the diagram incorrect here?
