Green synthesis of a AgCl@AgI nanocomposite using Laminaria japonica extract and its application as a visible-light-driven photocatalyst.

A AgCl@AgI composite photocatalyst was greenly synthesized using Laminaria japonica extract as the source of halogen anions, and characterized by XRD, SEM, TEM and XPS techniques. The photocatalytic activity and photochemical stability of the AgCl@AgI were investigated by the photodegradation of methyl orange (MO) azo dye under visible light illumination ( λ > 420 nm). The AgCl@AgI composite showed good photochemical stability and much higher photocatalytic activity than that of single AgCl and AgI. Mechanism studies showed that the main active species are photoinduced holes (h + ) and superoxide anion radicals (·O 2 - ). Finally, a plausible mechanism for the separation of photoinduced charge carriers was proposed.