BiOBr Micro–Nanosheets: Controllable Synthesis and Piezoelectric and Photoelectric Properties

The intrinsic electric field in piezoelectric materials strongly controls the recombination dynamics, and choosing a specific piezoelectric material in designing a photocatalyst is of great interest. Herein, uniform BiOBr single-crystal micro–nanosheets with 2–8 μm side length and 100–300 nm thickness were suitably prepared using a hydrothermal method after optimizing the fabrication parameters. A near single-domain structure with reversible polarization switching was detected along with a typical butterfly-shape piezoelectric hysteresis loop, showing over 150 pm displacement under a ∼37 V bias voltage. Photoelectric characterization displayed almost a three times difference for the photoelectric anisotropy along and perpendicular to the plane, whereas the photoelectrochemical measurement indicated a low charge transfer resistance and a correspondingly efficient photoelectrochemical response under 365 nm laser, which are attributed to the significant increase in surface potential observed using Kelvin probe force microscopy and the potential internal field related to the piezoelectricity.