AgI/TiO2 nanocomposites: Ultrasound-assisted preparation, visible-light induced photocatalytic degradation of methyl orange and antibacterial activity

• A rapid and effective ultrasound-assisted precipitation preparation for AgI/TiO2 nanocomposites.
• Distinctive reduction of crystallite size of AgI nanoparticles after low-temperature calcination.
• Superior visible light induced photocatalytic activity of methyl orange and antibacterial activity.

AgI/TiO2 nanocomposites were prepared by an ultrasound-assisted precipitation process and subsequent low-temperature (350 °C) calcination. The crystal phase, morphology and optical properties of the AgI/TiO2 nanocomposites were characterized by X-ray diffraction, transmission electron microscopy and UV–vis absorption spectroscopy. After calcination, the crystallite size of AgI nanoparticles in the AgI/TiO2 nanocomposites decreased, and visible light absorption intensity of the AgI/TiO2 nanocomposites was significantly enhanced. The AgI/TiO2 nanocomposites after calcination exhibited the superior photocatalytic activity for methyl orange degradation and killing of Escherichia coli under visible light irradiation. The improvement of photocatalytic activity could be attributed to two reasons, namely, reduced crystallite size and enhanced visible light absorption of AgI nanoparticles in calcined AgI/TiO2 nanocomposites. The trapping experiments demonstrated that superoxide radical (O2−) and holes (h+) were the main reactive species for the photodegradation of methyl orange under visible light irradiation. The ultrasound-assisted preparation approach is efficient and facile, which promotes large-scale production and application of AgI/TiO2 nanocomposites in photocatalytic degradation of organic pollutants, disinfection and other fields.