β particles induced directional inward migration of oxygen vacancies: Surface oxygen vacancies and interface oxygen vacancies synergistically activate PMS

In this work, a high-energy β electron beam was applied to promote the generation and directional inward migration of surface oxygen defects. The valence band potential changed to a high potential due to the transfer of surface oxygen vacancies on BiVO4/Bi2O3−x. Interface oxygen vacancies have significant advantages in inducing the formation of oxygen vacancy levels and reducing the band gap energy. Surface oxygen vacancy and vacancy levels can prevent the recombination of photogenerated carriers. The electrons enriched in the surface oxygen vacancies can remarkably activate PMS with O−O bonds to degrade ciprofloxacin (CIP). The degradation kinetic constant and CIP mineralization rate of BiVO4/Bi2O3−x-450/PMS were 2.09 and 1.51 times higher than those of BiVO4/Bi2O3−x/PMS, respectively. BiVO4/Bi2O3−x-450 with a lower relative content of surface oxygen vacancies (24.70%) exhibited a stronger activation ability. Obviously, the change of band structure caused by interface oxygen vacancies is the reason for increasing photoactivation efficiency of PMS.