An example of such a metal catalyst is, for example, fuel cells. In fuel cells, plant and catalyst acts in the same manner to speed up the reactions the oxidation and reduction reactions in an anode in a cathode. Now, if you want to learn more about fuel cells, check out the link above. So now let's look at homogeneous catalysts. Now, homogeneous catalysts are catalysts that are in the same state as our reactant, usually liquid or gas. A great and common example of a homogeneous catalyst are acids.