Oxygen-deficient AgIO₃ for efficiently photodegrading organic contaminants under natural sunlight

Defect engineering is regarded as an effective strategy to boost the photo-activity of photocatalysts for organic contaminants removal. In this work, abundant surface oxygen vacancies (Ov) are created on AgIO₃ microsheets (AgIO₃-O_V) by a facile and controllable hydrogen chemical reduction approach. The introduction of surface Ov on AgIO₃ broadens the photo-absorption region from ultraviolet to visible light, accelerates the photoinduced charges separation and migration, and also activates the formation of superoxide radicals (•O₂^-). The AgIO₃-O_V possesses an outstanding degradation rate constant of 0.035 min^-1, for photocatalytic degrading methyl orange (MO) under illumination of natural sunlight with a light intensity is 50 mW/cm², which is 7 and 3.5 times that of the pristine AgIO₃ and C-AgIO₃ (AgIO₃ is calcined in air without generating Ov). In addition, the AgIO₃-O_V also exhibit considerable photoactivity for degrading other diverse organic contaminants, including azo dye (rhodamine B (RhB)), antibiotics (sulflsoxazole (SOX), norfloxacin (NOR), chlortetracycline hydrochloride (CTC), tetracycline hydrochloride (TC) and ofloxacin (OFX)), and even the mixture of organic contaminants (MO-RhB and CTC-OFX). After natural sunlight illumination for 50 min, 41.4% of total organic carbon (TOC) for MO-RhB mixed solution can be decreased over AgIO₃-O_V. In a broad range of solution pH from 3 to 11 or diverse water bodies of MO solution, AgIO₃-O_V exhibits attractive activity for decomposing MO. The MO photo-degradation process and mechanism over AgIO₃-O_V under natural sunlight irradiation has been systemically investigated and proposed. The toxicities of MO and its degradation intermediates over AgIO₃-O_V are compared using Toxicity Estimation Software (T.E.S.T.). Moreover, the non-toxicity of both AgIO₃-O_V catalyst and treated antibiotic solution (CTC-OFX mixture) are confirmed by E. coli DH5a cultivation test, supporting the feasibility of AgIO₃-O_V catalyst to treat organic contaminants in real water under natural sunlight illumination.