Photodeposition of CoO nanoparticles on BiFeO nanodisk for efficiently piezocatalytic degradation of rhodamine B by utilizing ultrasonic vibration energy.

Piezoelectric materials have received much attention due to their great potential in environmental remediation by utilizing vibrational energy. In this paper, a novel piezoelectric catalyst, CoO nanoparticles anchored BiFeO nanodisk composite, was intentionally synthesized via a photodeposition method and applied in piezocatalytic degradation of rhodamine B (RhB) under ultrasonic vibration. The as-synthesized CoO/BiFeO composite presents high piezocatalytic efficiency and stability. The RhB degradation rate is determined to be 1.29 h, which is 2.38 folds higher than that of pure BiFeO. Via optimizing the reaction conditions, the piezocatalytic degradation rate of the CoO/BiFeO can be further increased to 3.20 h. A thorough characterization was implemented to investigate the structure, piezoelectric property, and charge separation efficiency of the CoO/BiFeO to reveal the nature behind the high piezocatalytic activity. It is found that the CoO nanoparticles are tightly adhered and uniformly dispersed on the surface of the BiFeO nanodisks. Strong interaction between CoO and BiFeO triggers the formation of a heterojunction structure, which further induces the migration of the piezoinduced holes on the BiFeO to CoO nanoparticles. The recombination of electron-hole pairs is retarded, thereby increasing the piezocatalytic performance greatly. This work may offer a new paradigm for the design of high-efficiency piezoelectric catalysts.