AgI loading BiOI composites with enhanced photodegradation efficiency for bisphenol A under simulated solar light

Highlights: • Novel hierarchical AgI-BiOI microsphere was synthesized via solvothermal method. • 1.25% AgI loading BiOI (AgI-BiOI(1–8)) greatly enhanced photodegradation of BPA. • Photogenerated h⁺ and O₂^{• −} radicals are mainly responsible for BPA degradation. • The eco-toxicity of AgI-BiOI(1–8) and intermediates of BPA were evaluated. • The photocatalytic mechanism of AgI loading BiOI heterojuncture was proposed. -- Abstract: Bismuth oxyiodide (BiOI) is a narrow band gap semiconductor which can be driven by visible irradiation. In order to efficiently separate photo-generated carriers and utilization of visible light, a facile solvothermal approach was used to synthesize a novel AgI loading BiOI 3D hierarchical composite (AgI-BiOI). The AgI-BiOI with Ag and Bi molar ratio of 1:8 (AgI-BiOI (1–8)) showed great enhancement for photocatalytic degradation of bisphenol A (BPA) with pseudo-first degradation rate constant about 3.7 or 14.5 times than that of pristine BiOI or AgI under simulated solar light. This synergistic enhancement for BPA degradation on AgI-BiOI(1–8) is mainly ascribed to enhancing the light absorption intensity and accelerating photo-generated carriers separation due to the formation of AgI-BiOI heterojunction. Free radical quenching experiments proved that positive holes (h⁺) and superoxide (O₂^{• −}) radicals were dominantly responsible for the degradation of BPA rather than singlet oxygen (¹O₂) or hydroxyl radicals (• OH). The AgI-BiOI(1–8) hardly showed any ecotoxicity to C. elegans through lethal experiments. The luminance bacteria acute toxicity of degradation intermediates of BPA increased before 30 min then reduced significantly with reaction. The good durability and environmental-friendly characteristics make AgI-BiOI(1–8) catalyst to be a good solar light-driven candidate.