Oriented Plate-like KNbO3 Polycrystals: Topochemical Mesocrystal Conversion and Piezoelectric and Photocatalytic Responses

Plate-like KN oriented polycrystals haveexcellent piezoelectricand photocatalytic properties. KNbO3 (KN) with a perovskite structure isan outstandingrepresentative of lead-free piezoelectric materials, and its mesocrystalshave broad application prospects in the fields of catalysis, energystorage, and conversion. However, the formation conditions of KN mesocrystalsreported so far are difficult owing to their high aspect ratio andexcellent preferred orientation. In this study, the solvothermal processwas used successfully to prepare the flake-like potassium salt ofLindquist hexaniobate (K8Nb6O19 & BULL;10H(2)O). Subsequently, the precursor niobate was calcined to preparetwo-dimensional (2D) plate-like KN mesocrystals. The formation mechanismof the plate-like KN mesocrystals is further revealed from a pairedtopochemical mesocrystal conversion of K8Nb6O19 & BULL;10H(2)O niobate. Finally, the microscopicpiezoelectric and photocatalytic responses of the obtained plate-likeKN mesocrystals were investigated. The high piezoelectric coefficientof plate-like KN mesocrystals implies that excellent charge separationpromotes the photocatalytic performance of rhodamine B (RhB). Thisstudy provides a strategy for the efficient application of 2D orientedmaterials in the field of piezoelectricity and photocatalysis.

Automated summary

In this study, flake-like potassium salt of Lindquist hexaniobate precursor was prepared by solvothermal process and then calcined to obtain plate-like KN mesocrystals. The formation mechanism of the mesocrystals was revealed through topochemical conversion. The obtained mesocrystals showed excellent piezoelectric and photocatalytic properties, indicating their potential for application in the fields of piezoelectricity and photocatalysis.