A novel Ag@AgBr-Ag2Mo3O10 ternary core-shell photocatalyst: Energy band modification and additional superoxide radical production

Abstract

A novel Ag@AgBr-Ag2Mo3O10 ternary core-shell system and a series of AgBr-Ag2Mo3O10 hybrids were prepared using a facile in-situ anion-exchange method. Structure and morphology characterization revealed the formation of the Ag@AgBr-Ag2Mo3O10 ternary system. Photoluminescence (PL) results indicated the heterojunction structure and the Ag0 synergistically facilitated the separation of the photogenerated charge carriers. UV–Vis diffuse reflectance spectra (DRS) demonstrated that photosensitive AgBr and Ag strongly broadened the visible light absorption range, with the onset of absorption extending from 460 nm to 500 nm. Degradation experiments suggested that the photocatalytic performance of the Ag@30%AgBr-Ag2Mo3O10 sample was remarkably improved compared to those of the Ag2Mo3O10 and the AgBr-Ag2Mo3O10 hybrids. Significantly, radical trapping experiments revealed that although the conduction band (CB) potentials of Ag2Mo3O10 and AgBr were not suitable for the formation of the superoxide radical (O2−), the ternary system produced O2− efficiently. The enhanced production of the O2− radical may be due to the band bending of CB that was caused by the equilibration of the Fermi energies of Ag and AgBr-Ag2Mo3O10. This study strongly suggests that design and synthesis of novel photocatalysts that increase the amount of radical species is a potential strategy for boosting photocatalytic performance.