Oxygen Vacancy-Mediated Microflower-like BiOI for Reactive Oxygen Species Generation through Piezo-Photocoupling Effect.

Photocatalytic reactive oxygen species (ROS) evolution with BiOI still suffers from sluggish charge carrier dynamics and limited light absorption. Herein, abundant oxygen vacancies (OVs) were introduced into the microflower-like BiOI, and its ROS generation toward organic dye degradation under the synergistic effect of visible light and ultrasound irradiation was investigated. Benefiting from the broadened visible-light absorption range, stronger piezoresponse, and higher carrier transport efficiency in OV-enriched BiOI (2-PEG-BiOI), both its photocatalytic and piezocatalytic degradations were improved. More importantly, its piezo-photocatalytic degradation performance was greater than the sum of the corresponding photocatalysis and piezocatalysis, indicating a strong coupling effect. In addition, the piezo-photocatalytic yield of O with 2-PEG-BiOI was 1.5 times higher than that with BiOI, and it was also 4.3 and 3.1 times higher than its single photocatalysis and piezocatalysis, respectively. Interestingly, no noticeable OH was detected in the case of visible-light irradiation, while the piezocatalytic and piezo-photocatalytic yields of OH were 3.6 and 5.3 μmol g h, respectively, with OV-enriched BiOI, surpassing the pristine BiOI as well. This work advances the coupling effect between photocatalysis and piezocatalysis as a new strategy for efficient ROS generation and also discloses the positive role of oxygen vacancies in improving multiresponsive catalysis.