Hydrothermal doping of Ag into three types of potassium niobates

Abstract

Three types of Ag-doped potassium niobates, a layered K₄Nb₆O₁₇·nH₂O, a pyrochlore-type (K,H)NbO₃·nH₂O, and a perovskite-type KNbO₃, were synthesized via a hydrothermal reaction. The layered-type K₄Nb₆O₁₇·nH₂O was prepared at 240°C using KOH/Nb₂O₅ = 6; the pyrochlore-type compound was prepared at 220°C using KOH/Nb₂O₅ = 10; and the orthorhombic perovskite-type compound was prepared at 260°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.