Synthesis of a novel AgI/BiOI nanocomposites and their high-efficiency visible-light driven photocatalytic degradation performance for norfloxacin

The AgI/BiOI composites were prepared with BiOI nanosheets as the substrate by in-situ ion exchange and characterized by a series of characterization methods. The photocatalytic performance tests showed that the effective separation of photogenerated electron-hole pairs as well as the photocatalytic activities of the AgI/BiOI composites could be achieved by adjusting the Ag/Bi molar ratios, which may result in changes in composition and structure of AgI/BiOI composites. Among them, the AgI/BiOI-1.2 sample with a Ag/Bi molar ratio of 1.2 demonstrated Bi5O7I composition and the highest separation efficiency of photogenerated electron-hole pairs as well as the best photocatalytic performance for norfloxacin (NOR) photodegradation. More than 98.8% of NOR could be removed on over AgI/BiOI-1.2 within 120 min under the optimum conditions. Radical quenching experiments confirmed that the photo-generated holes and ∙O2‒ radicals played significant roles during the process of photocatalytic NOR degradation. A possible Z-type heterojunction mechanism for photocatalytic degradation of NOR over AgI/BiOI-1.2 was proposed.