Photocatalytic hydrogen evolution with fibrous titania prepared by the solvothermal reactions of protonic layered tetratitanate (H₂Ti₄O₉)

Various titania such as monoclinic titania, anatase and rutile were prepared via the heat treatment of protonic layered tetratitanate. The microstructure and hydrogen evolution activity of titania changed significantly depending on the reaction conditions. Generally, the hydrogen evolution activity of titania prepared by solvothermal reactions in water and alcohols at 200-325°C was much higher than that prepared by calcination in air. The solvothermal reactions using methanol and ethanol were much more efficient in increasing the hydrogen evolution activity than when water was used. When the titania formed by the solvothermal reaction in methanol was heated in air, the hydrogen evolution activity decreased with increasing temperature; however, the powders possessed higher hydrogen evolution activity than those produced directly by calcining the protonic layered tetratitanate at the same temperature without a solvothermal treatment. (C) 2000 Elsevier Science Ltd.