Hydrogen production using highly active titanium oxide-based photocatalysts

Applying the principle of water decomposition over photoelectrochemical cells to heterogeneous photocatalytic systems using powdered semiconductors is now a field of great interest, encouraging new fundamental investigations into chemical reactions which take place at the electrode surfaces in the electrochemical cells. In the present review, we have focused on systems, which can convert solar energy into chemical energy by using TiO2 photocatalysts. The photocatalytic decomposition of water under UV light irradiation has been achieved with systems using various nanoparticle photocatalysts such as TiO2. However, recently, visible light-responsive TiO2 thin films photocatalysts have been successfully prepared by a radio frequency magnetron sputtering (RF-MS) deposition method. These thin film photocatalysts were found to have enough potential for the separate evolution of H-2 and O-2 from water under solar light. The TiO2 thin films were prepared on metal substrates by RF-MS deposition and mounted on H-type containers filled with water. This unique system enabled the separate evolution of H-2 and O-2 from water under sunlight irradiation, opening new opportunities for the practical on-site production of pure and clean H-2 from water using abundant and clean sunlight in a safe, environmentally harmonious way.