Photoelectrochemical Water Electrolysis

Photocatalysis is a water splitting event that produce hydrogen using photon energy. Most photocatalyst materials are made of semiconductor material because the semiconductor material has an energy gap that allows it to produce electron holes if it is to give the photon energy from a source. This electron-hole pair will later cause a water splitting event. So far, the most widely used semiconductor material as photocatalyst is TiO₂. Interest in TiO₂ to be used as photocatalyst compared to other semiconductor materials, TiO₂ is known to have various important advantages, for applications of hydrogen production from water (fractionation of water), including having high stability, corrosion resistance, abundant availability in nature and relatively inexpensive prices. In general, the TiO₂ photocatalyst which has been developed so far can only produce hydrogen optimally if it operates in an area under visible light. This is due to the band gap energy of the TiO₂ semiconductor material greater than the photonic energy produced by visible light. Efforts to design the TiO₂ catalyst to improve its performance in the water splitting, both in the ultraviolet (UV) and visible light zones, have been made by giving doping from other materials (metallic or non- metallic) such as: TiO₂/Pt -RuO₂, Rh-NaOH/TiO₂ (anatase), TiO₂ (P₂₅)/Pt, La₂Ti₂O₇ in layers, loose LaTiO₃/Ni and SrTiO₃. Although some of these studies in the engineering of TiO₂ photocatalysts have been successful, the Rh-NaOH/TiO₂ (anatase) which produces the most hydrogen in the water splitting event is approximately 449 mol H₂/h using a lamp source of 500 W-Hg.