Photocatalytic water splitting into H₂ and O₂ over various tantalate photocatalysts

Photocatalytic water splitting into H₂ and O₂ over various tantalates was reviewed and factors affecting photocatalytic activities of tantalates were discussed from a viewpoint of the crystal structure and the energy structure. Many tantalates, K₃Ta₃Si₂O₁₃, alkali and alkaline earth tantalates, were highly active photocatalysts for water splitting. The high activities were mainly due to the high conduction band level consisting of Ta5d orbitals. NiO-loaded NaTaO₃ with the distorted perovskite structure showed the highest activity among tantalates. Moreover, the activity of the NiO/NaTaO₃ photocatalyst was remarkably improved by doping of lanthanoids. The apparent quantum yield of NiO/NaTaO₃ doped with lanthanum was ca. 50% at 270 nm.