"Water splitting" simply refers to the process of separating water molecules into its two main components, which are hydrogen and oxygen gases. Full definition
For one thing, sufficient light must reach the solar cell in order to create the voltage for water splitting — despite the additional layers of material. (sciencedaily.com)
The method advanced by the new device, called direct solar water splitting, only uses water and light from the sun. (futurity.org)
It also had an unusually high concentration of charged particles, perhaps the result of water splitting into hydrogen and oxygen. (sciencenews.org)