Controllable preparation of high tetragonal phase BaTiO3 nano/microstructure and its boosting piezocatalytic properties

Abstract

BaTiO3 terrace-like nano/microstructure were synthesized via a facile solvothermal method without surfacatant or template by controlling pH value. The phase structure, morphology and properties of the samples were characterized by XRD, FT-IR, XPS, SEM, UV–vis and ESR spectrum, etc. The piezoelectric potential analysis are calculated by finite element method simulation for BaTiO3 prepared at different pH values under ultrasonic vibration. Morphology and crystal phase transform mechanism of BaTiO3 at different pH values are proposed, respectively. The results show that pH value has a significant effect on the phase, crystallinity, morphology, size and piezocatalytic performance of BaTiO3. When pH value is 10, BaTiO3 exhibits spherical shape with an average size of ∼200 nm. With the increase of pH value, the morphology transforms grape-like shape from terrace-like shape. The transformation mechanism for BaTiO3 is proposed to be a two–step growth model: initial nucleation and ripen, an oriented attachement accompanied by Ostwald ripening. H+ ions in OH− group occupy the Ba2+ position and affect the supersaturation of Ti (OH)62−, thereby blocking the migration channel of Ba2+ and changing the crystal symmetry, resulting in changes in the content of tetragonal phase. FEM simulated shows the electric potential of BaTiO3 is dominated by their morphologies. Compared with other samples, the best piezocatalytic performance of BaTiO3 terrace-like nano/microstructure is demonstrated at pH = 12, which is the rate constant k of 15.5 × 10−3 min−1 by degrading 93 % of RhB dye solution in 180min, and keep almost unchanged after five cycles. The attractive piezocatalytic properties are considered to benefit from BaTiO3 terrace-like nano/microstructure, which is composed of the numerous nanounits self-assembly micrometer-scale structure.