Synthesis of nitrogen-doped KNbO₃ nanocubes with high photocatalytic activity for water splitting and degradation of organic pollutants under visible light

The effects of KOH concentration (10–30 M) on the morphology of KNbO₃ produced from Nb₂O₅ by hydrothermal synthesis have been investigated. High purity KNbO₃ nanocubes have been obtained using 30 M KOH at 200 °C. The KNbO₃ nanocubes can be readily doped with nitrogen by heating with urea at 425 °C without significant change in morphology. The band gap of KNbO₃ decreases from 3.13 to 2.76 eV as a result of N-doping, the surface area also increases substantially. The photocatalytic activity of the N-doped KNbO₃ nanocubes has been evaluated by photodegradation of four organic contaminants (rhodamine B, orange G, bisphenol A and pentachlorophenol) as well as water splitting under visible light irradiation. The results show that the photocatalytic activity of N-doped KNbO₃ is significantly higher than that of pure KNbO₃ nanocubes and Degussa TiO₂ P25 under visible light irradiation. Copyright © 2013 Published by Elsevier B.V.