Novel CQDs/BiOI Microspheres with Gradient Oxygen Vacancies for Efficient Photocatalytic Performance Boosting by the Synergism of Reactive Oxygen and Iodine Species

Abstract The synergy of reactive oxidative species (ROSs: ⋅OH, ⋅O 2 − and 1 O 2 ) and reactive iodine species (RISs: ⋅I and ⋅I 2 − ) is conclusive to driving organic pollutant degradation in various aquatic environments. Over the past years, rational design of Vis‐NIR responsive photocatalyst with enhanced photocatalytic performance has attracted drawing attention. Herein, CQDs/BiOI composites with up‐conversion photoluminescence (UCPL) properties and oxygen vacancies was constructed for tetracycline (TC) and oxytetracycline (OTC) degradation. The apparent kinetic constant of the 4‐CQDs/BiOI is 2.13 and 2.38 times on pure BiOI. The excellent photodegradation efficiency can be attributed to the enhanced light absorption originated from the up‐conversion property and improved charge separation efficiency. Furthermore, the iodine free radicals (⋅I) and superoxide free radicals (⋅O 2 − ) played a crucial role in the photodegradation procedure. I − from BiOI could be partially oxidized to form ⋅I. At the same time, the electron capture traps formed by Oxygen vacancies can promote the production of ⋅O 2 − . Remarkably, the removal efficiency of TC and OTC was still maintained at 80 % by 4‐CQDs/BiOI under different water quality conditions due to the synergy of ⋅O 2 − with ⋅I. This work sheds light on a new treatment for the synergistic degradation of pollutants in complex water by RISs and ROSs.