In-situ preparation of Z-scheme AgI/Bi5O7I hybrid and its excellent photocatalytic activity

Abstract

The aim of this work was to synthesize, characterize and evaluate the photocatalytic activity of AgI/Bi5O7I composite photocatalyst under visible light irradiation. The photocatalyst was prepared by a simple one-step ionic reaction between Bi5O7I microrods and AgNO3 solutions, and was characterized by various techniques including X-ray diffraction (XRD), Raman spectroscopy (Raman), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (DRS), and photoluminescence spectroscopy (PL). The characterizations indicate that AgI particles were closely anchored on Bi5O7I micronods. During the photocataytic reaction, the composite was actually an Ag-AgI-Bi5O7I ternary system. The plasmonic effect of the formed Ag nanoparticles improved the visible light absorption performance, which benefits the photocatalytic reaction. However, more important was the formed heterojunction structure in the composite, which efficiently promoted the separation of electron-hole pairs by a plasmonic Z-scheme mechanism, and ultimately enhanced the photocatalytic activity. The optimal AgI/Bi5O7I composite showed a RhB degradation rate of 0.046min−1, which was 3.83 and 6.57 times higher than those of Bi5O7I and AgI, respectively. This work may provide some insight into the design of novel and highly efficient Z-scheme visible-light photocatalysts.