Rodlike AgI/Ag₂Mo₂O₇ Heterojunctions with Enhanced Visible-Light-Driven Photocatalytic Activity

Novel AgI/Ag₂Mo₂O₇ heterojunctions were prepared by reacting Ag₂Mo₂O₇ microrods with an aqueous KI solution at room temperature. The composite materials, compared with neat AgI and Ag₂Mo₂O₇, showed much higher activities in the photocatalytic degradation of aqueous rhodamine B, methyl orange, tetracycline hydrochloride, and levofloxacin solutions under visible-light irradiation. The structures, morphologies, and other physicochemical properties of AgI, Ag₂Mo₂O₇, and AgI/Ag₂Mo₂O₇ composites were studied via various characterization techniques. The active species involved in the photocatalytic process were examined via radical-capturing experiments and electron spin resonance. Superoxide anion radicals (^•O₂ ^-) and photogenerated holes (h⁺) were found to be the main active species. Photocatalytic mechanisms were proposed and reasons for the enhanced photocatalytic activity were explained.