Potassium niobate nanostructures: controllable morphology, growth mechanism, and photocatalytic activity

Abstract

Various potassium niobate (KNbO₃) nanostructures, including nanowires, nanotowers, nanocubes and nanorods, were successfully fabricated through rather facile hydrothermal processes. By adjusting the concentration of potassium hydroxide, reaction temperature and reaction time, the product morphologies can be easily controlled. High crystallinity as well as the active (001) crystal plane exposed on KNbO₃ nanocrystals offer enhanced photocatalytic activity for rhodamine B decomposition in aqueous solutions under UV-visible light irradiation. The level of photocatalytic activity depends strongly on the microstructure of KNbO₃ and the photoreactivity towards RhB degradation follows the order of KNbO₃ nanocubes > nanowires > nanorods > nanotowers. The KNbO₃ nanocubes prepared at 200 °C for 7 days in the presence of 6.5 M KOH exhibited the enhanced photocatalytic performance for the degradation of RhB to 89% after 240 min of irradiation under a sunlight simulator.