Synthesis of potassium titanoniobate in supercritical and subcritical water and investigations on its photocatalytic performance

Abstract

Synthesis of potassium titanoniobate (KTiNbO 5) powder was achieved by the hydrothermal process in supercritical and subcritical water using Nb 2O 5 fine powder, titanium tetra-isopropoxide and potassium hydroxide aqueous solution as starting reactants. The novel hydrothermal process for synthesizing KTiNbO 5 powders employs significantly reduced reaction temperature (300–400 °C) in comparison with the conventional solid-state synthesis and polymerizable complex methods (1100 and 700 °C), to get an advantage in the preparation of multicomponent oxide compounds such as KTiNbO 5 with pure phase, thin rectangular particles and large surface area. Hydrothermal temperature, time duration and alkaline concentration employed in the synthesis determined the structure and particle morphology of the final products. The hydrothermally synthesized KTiNbO 5 powders with ruthenium loading were used for the photocatalytic hydrogen evolution from aqueous methanol solution. The surface area is responsible for the highly photocatalytic performance of ruthenium loaded KTiNbO 5 powders hydrothermally synthesized in supercritical and subcritical water.