Oxygen Vacancy-Mediated Microflower-like Bi<sub>5</sub>O<sub>7</sub>I for Reactive Oxygen Species Generation through Piezo-Photocoupling Effect
Yongfei Cui, Wei Liu, Liangliang Chang, Cuicui Wang, Subhajit Pal, Joe Briscoe, Zhuo Wang
Abstract
Photocatalytic reactive oxygen species (ROS) evolution with Bi 5 O 7 I still suffers from sluggish charge carrier dynamics and limited light absorption. Herein, abundant oxygen vacancies (OVs) were introduced into the microflower-like Bi 5 O 7 I, 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 Bi 5 O 7 I (2-PEG-Bi 5 O 7 I), 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 2 – with 2-PEG-Bi 5 O 7 I was 1.5 times higher than that with Bi 5 O 7 I, 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 –1 h –1, respectively, with OV-enriched Bi 5 O 7 I, surpassing the pristine Bi 5 O 7 I 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.