Hydrothermal doping of Ag into three types of potassium niobates

Three types of Ag-doped potassium niobates, a layered K4Nb6O17 center dot nH(2)O, a pyrochlore-type (K,H)NbO3 center dot nH(2)O, and a perovskite-type KNbO3, were synthesized via a hydrothermal reaction. The layered-type K4Nb6O17 center dot nH(2)O was prepared at 240 degrees C using KOH/Nb2O5 = 6; the pyrochlore-type compound was prepared at 220 degrees C using KOH/Nb2O5 = 10; and the orthorhombic perovskite-type compound was prepared at 260 degrees C using KOH/Nb2O5 = 40. Ag ions were intercalated to the interlayer of the layered compound and the tunnel of the pyrochlore-type compound, while Ag metal was loaded on the surface of the perovskite-type compound. The layered-and perovskite-type compounds exhibited photocatalytic activity for phenol degradation under ultraviolet light irradiation; however, the pyrochlore-type compound did not exhibit good photocatalytic activity. (C) 2018 The Ceramic Society of Japan. All rights reserved.