Photoelectrochemical cell
Photoelectrochemical cells extract electrical energy from light, including visible light. Each cell consists of a semiconducting photoanode and a metal cathode immersed in an electrolyte.
Some photoelectrochemical cells simply produce electrical energy, while others produce hydrogen in a process similar to the electrolysis of water. One type of the former is called Graetzel cells or dye-sensitized solar cells; these cells use dye-absorbed highly porous nanocrystalline titanium oxide (nc-TiO2). In the latter case, electrolysis of water to hydrogen and oxygen gas occurs when the anode is irradiated with electromagnetic radiation. This has been suggested as a way of converting solar energy into a transportable form, namely hydrogen.