Coupled piezo-pyro-photocatalysis of oxygen vacancies and Bi quantum dots co-modified BaTiO3 for highly efficient removal of ciprofloxacin

Understanding the synergistic promotion of photocarrier separation by multiple parameters is crucial to developing superior photocatalysts in environmental remediation. In this study, we have engineered BaTiO3 photocatalyst by creating oxygen vacancies (OVs) and decorating Bi quantum dots (QDs) on its surface, and then elucidated its piezo-pyro-photocatalysis and mechanism for ciprofloxacin (CIP) elimination. The optimal OVs-/Bi QDs-engineered sample (labeled as 7 %Bi@BTO-325 °C) exhibits a photodegradation activity, under simulated-sunlight irradiation, that is improved by 3.8 times over that of pristine BTO. This phenomenon can be explained due to the improved visible-light absorption and photocarrier separation by OVs and Bi QDs. Moreover, when the simulated-sunlight illumination (photocatalysis) was companied with ultrasonic irradiation (piezocatalysis) and cold-hot alternation (pyrocatalysis), the coupling of piezo-pyro-photocatalysis shows a further improvement in the CIP removal with a synergistic enhancement factor SF = 1.77. The enhanced piezo-pyro-photocatalysis is ascribed to the fact that the piezoelectric/pyroelectric polarization field facilitates the separation of photocarriers (particularly the bulk photocarriers). Experiment and theory were combined to deeply study the catalysis mechanism. Moreover, the influence of multiple parameters on the CIP elimination was investigated and analyzed by machine learning to establish the best prediction model.