Highly Efficient Degradation of Perfluorooctanoic Acid over a MnO_x‐Modified Oxygen‐Vacancy‐Rich In₂O₃ Photocatalyst

Abstract

Abstract Destructive removal of perfluoroalkyl substances (PFASs) from water has been an emerging concern, as the C−F bond cleavage requires energy‐consuming advanced oxidation approaches. The conventional photocatalyst materials exhibit insufficient PFAS degradation due to either a weak absorption ability towards PFASs or a limited reaction oxygen species (ROS) generation. Herein, In 2 O 3 , which has an excellent absorption ability towards perfluorooctanoic acid (PFOA), is chosen as the main catalyst materials. Oxygen vacancies are then generated on the surface of In 2 O 3 to assist the PFOA adsorption. Further depositions of the MnO x cocatalyst on the surface of In 2 O 3 are performed to enhance the ROS generation efficiency. Based on the above design, the MnO x ‐modified oxygen‐vacancy‐rich In 2 O 3 photocatalyst shows a remarkably improved PFOA photodegradation and defluorination efficiencies under the solar light irradiation as compared with the pristine and commercial In 2 O 3 . The photodegradation pathway of PFOA is investigated. The experimental results from the PFOA adsorption analysis and electron spin resonance (ESR) spectra confirm the enhanced adsorption ability and the higher ROS generation efficiency, respectively. The catalyst is further tested in the presence of different anions and cations, where rapid degradation of PFOA is also observed, indicating the potential of the composite materials applied in the practical treatment of PFAS‐contaminated water.