One technology that needs a catalyst to work is a hydrogen fuel
cell. In these devices, hydrogen gas (H2) reacts with oxygen gas
(O2) to make water (H2O) and electricity. These systems can be
found in a hydrogen vehicle where they create the electricity to
power the engine. The fuel cell needs to separate the atoms in
molecules of hydrogen and oxygen so that those atoms can reshuffle
to create new molecules (water). Without some assistance, though,
that reshuffling would take place very slowly. So the fuel cell
uses a catalyst — platinum — to propel those reactions along.
~I have loved the stars too fondly to be
fearful of the night~