Synergistic effect of Fe doping and oxygen vacancy in AgIO for effectively degrading organic pollutants under natural sunlight.

In this work, a series of hydrogenated Fe-doped AgIO (FAI-x) catalysts are synthesized for photodegrading diverse azo dyes and antibiotics. Under the irradiation of natural sunlight with a light intensity of ∼60 mW/cm, the optimum FAI-10 exhibits a considerable rate constant for decomposing methyl orange (MO) of 0.067 min, about 7.4 times higher than that of AgIO (0.009 min), and 24.6% and 83.8% of MO can be decomposed over AgIO and FAI-10 after irradiation for 40 min. In the amplification photodegradation experiments with using 0.5 g catalyst and 400 mL MO dye solution (10 mg/L), FAI-10 possesses greatly higher photoreactivity to common semiconductors (ZnO, TiO, InO and BiMoO), and the photodegradation rates over FAI-10 are 92%. Particularly, the FAI-10 shows superior stability, the activity of which remains unaltered after 8 continuous cycles. Foreign ions and water bodies have slight effect on the activity of FAI-10, but the MO degradation rates are decreased by adjusting pH values, especially when pH = 11 because of the strong electrostatic repulsion between MO and FAI-10. FAI-10 can also effectively decompose another azo dye (rhodamine B (RhB)) and diverse antibiotics (sulflsoxazole (SOX), chlortetracycline hydrochloride (CTC), tetracycline hydrochloride (TC) and ofloxacin (OFX)). The activity enhancement mechanism of FAI-10 has been systemically investigated and is ascribed to the promoted photo-absorption, charge separation and transfer efficiency, and affinity of organic pollutants, owing to the synergistic effect of Fe doping and oxygen vacancy (Ov). The photocatalytic mechanisms and process for decomposing MO are verified and proposed based on radical trapping experiments and liquid chromatography-mass spectrometry (LC-MS). This work opens an avenue for the fabrication of effective photocatalysts toward water purification.