Phase-pure BaTi4O9 powders were prepared at temperatures higher than 700 °C by the Pechini-type polymerizable complex (PC) technique, based upon polyesterification between citric acid and ethylene glycol. BaTi4O9 was subsequently converted to nanocomposite materials by modifying its surface with ultrafine particles of RuO2, and the nanocomposite was used as photocatalyst for the decomposition of water into H2 and O2. The RuO2/PC-BaTi4O9 material prepared at 800 °C showed a photocatalytic activity ∼5 times higher than that of a sample prepared by a solid-state reaction at 1100 °C. The activity did not scale simply with the specific surface area of the samples; e.g. the sample having a surface area of 20.4 m2/g (prepared at 700 °C ) showed, unexpectedly, a ∼50% reduction in the activity when compared with that of a sample having a surface area of 7.6 m2/g (prepared at 800 °C ). The anomalous reduction in the activity was interpreted as a consequence of the increased number of lattice defects acting as inactivation centers. The average emission lifetime estimated from an emission decay curve decreased from 4.0 to 2.5 ns with a decrease in the preparation temperature from 900 to 700 °C, suggesting that the number of lattice defects is increased as the temperature is lowered.

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We demonstrate applicability of (NH4)8[Ti4(C6H4O7)4(O2)4]·8H2Owater-soluble titanium complexfor preparation of oxide materials containing titanium in the form of thin films by dip coating and fine powders by the sol−gel method. Anatase thin films and RuO2/BaTi4O9 powders were selected as examples of photocatalytic materials, which synthesis is not trivial and functional properties depend essentially on the sample purity and morphology. The utilized technique yielded excellent samples quality; the obtained films and powders demonstrate good photocatalytic activity.

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A polymerized complex (PC) technique was utilized to prepare high-purity barium tetratitanate (BaTi4O9) fine powders at a low temperature (700 °C). BaTi4O9 via the PC route, combined with RuO2, exhibited 2.4 times larger photocatalytic activities for the decomposition of water compared to those for a sample prepared by a solid-state reaction method. A considerably large surface area (∼30 m2/g) of the BaTi4O9/RuO2 powder via the PC route, when compared with ∼5 m2/g for the solid-state reaction powder, was supposed to be one of the key factors responsible for the high photocatalytic activity observed.