Size‐Tunable BaZrO₃ Cubes and Rhombic Dodecahedra Exhibiting Facet‐Dependent Optical, Photocatalytic, and Piezocatalytic Behaviors

Abstract BaZrO 3 cubes with four average sizes from 167 to 671 nm, and rhombic dodecahedra with four size ranges from 90 to 627 nm, have been synthesized solvothermally. In addition to slight cell constant differences between cubes and rhombic dodecahedra, synchrotron X‐ray diffraction (XRD) patterns verify size‐related peak shifts especially for rhombic dodecahedra. The cubes also show peak asymmetry that can be fitted with bulk and surface layer lattice components. Fast fourier transform (FFT) of high‐resolution transmission electron microscopy (HR‐TEM) images reveal greater lattice point deviations in the area near the particle surfaces. The lattice disturbance and cell constant changes produce size and facet effects in their band gaps. Despite very low photocatalytic hydrogen evolution yields, cubes are moderately more active than rhombic dodecahedra in this reaction. However, rhombic dodecahedra exhibit a stronger piezoelectric response, and are piezocatalytically more active than cubes toward rhodamine B (RhB) degradation. These phenomena should be linked to their internal lattice variations.