Hydrogen purification
Most fuel cells are hydrogen based and often require ultra-pure hydrogen to operate effectively. Palladium can be used to generate, purify, store and detect hydrogen, thus performing many important functions in the hydrogen economy. The discovery of palladium's remarkable ability to absorb hydrogen has since led to sues which take advantage of this affinity.
As a thin membrane, palladium will allow hydrogen to permeate through the membrane, but block all other gases. The further discovery of the stability of palladium-silver alloys and the ability to manufacture membranes of these alloys made hydrogen purification using palladium-silver membranes possible.