File:Anatase (titania, TiO2) photocatalyst producing hydrogen.jpg

English: In the reaction here, photons from the light source (which is just out of frame to the right of the picture) hit the surface of the titania disc, exciting electrons within the atomic structure These then react with the water molecules, splitting it into its constituents of hydrogen and oxygen. In this experiment, chemicals dissolved in the water prevent the formation of oxygen, which would otherwise recombine with the hydrogen.