Photocatalytic barium titanates

Since BaTi40g and Na2TieOi3 have a pentagonal prism tunnel and a rectangular tunnel structure, respectively, we have paid attention to the role of the tunnel structures in photocatalysis. A barium titanate, Ba4Tii303o, in a series of Ba-Ti titanates was chosen as a representative with non-tunnel structure, and we have compared the photocatalytic activity and the ability for the production of surface radical species with uv irradiation between the tunnel and the non-tunnel titanates. 

Kohno, M., Kaneko, T., Ogura, S., Sato, K., Inoue, Y. 1998. Dispersion of ruthenium oxide on barium titanates (BasTij,0. , Ba.,Tij303, BaTi.,0, and BajTi,Oj, ) and photocatalytic activity for water decomposition. J Chem Soc Faraday Trans 94 89-94. 

Fig. 15.3 Comparison of photocatalytic activity on Ru02/barium titanates of (a)Ba6Tii70, (b)Ba4Tiu03o, (c) BaTi409 and (d) Ba2Ti9020.

Recently, we have shown that the combination of barium tetratitanate, BaTi40g and sodium hexatitanate, NagTigOis, with ruthenium oxides leads to active photocatalysts for water decomposition[1,2]. The unique feature of these photocatalysts is that no reduction of the titanates is required to be activated this is intrinsically different from conventional photocatalysts using TIO2 which are often heat-treated in a reducing atmosphere. Such different photocatalytic characteristics suggest that efficiency for the separation of photoexcited charges (a pair of electrons and holes) which is the most important step in photocatalysis is... 

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