Potassium hexatitanate photocatalysts prepared by a flux method for water splitting

•Potassium hexatitanate samples of various shapes were synthesized by a flux method.•Rhodium loaded potassium hexatitanate photocatalysts were active for water splitting.•Potassium hexatitanate photocatalysts consisting of fine hexagonal rod-like crystals exhibited high photocatalytic activity for water splitting.

Potassium hexatitanate (K2Ti6O13) photocatalysts were prepared by a flux method from K2CO3 and TiO2 by using a KCl flux with various concentration of solute and various cooling rate of the molten mixture. A low concentration of the solute and a moderately slow cooling rate provided fine hexagonal rod-like crystals of potassium hexatitanate, which would be formed through dissolution of the solutes in enough amount of the molten salt followed by crystallization and growth of potassium hexatitanate during the cooling step, presumably with fewer defects formation. The fine crystals of potassium hexatitanate loaded with rhodium cocatalyst continuously exhibited the best photocatalytic activity for water splitting among the photocatalysts prepared in this study including a sample prepared by a solid state reaction method.

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