In situ construction of a direct Z-scheme AgBr/α-Ag2WO4 heterojunction with promoted spatial charge migration and photocatalytic performance

Abstract

In this study, a direct Z-scheme AgBr/α-Ag₂WO₄ heterojunction was prepared via in situ anion exchange at room temperature. The construction strategy is energy- and time-saving for large scale syntheses. The α-Ag₂WO₄ cluster was tightly anchored by converted AgBr nanoparticles of small size in the range of 5–15 nm to induce an effective interfacial effect. The visible light photoactivity of the optimal sample AgBr/α-Ag₂WO₄-20% is drastically boosted by 53.4- and 26.4-fold towards the degradation of Rhodamine B (RhB) and phenol, respectively. Under the exposure of simulated sunlight, the photocatalytic degradation rate of RhB is also enhanced as high as 12.4 times compared with bare α-Ag₂WO₄. Besides the enhanced light harvesting, the improved photoactivity is mainly ascribed to the accelerated spatial separation of photoexcited carriers as evidenced by PL and photoelectrochemical analyses. Based on the energy band structure and reactive oxidation species, a solid Z-scheme heterojunction mechanism at the AgBr/α-Ag₂WO₄ interface is proposed and discussed. The study offers some insight into the design of hetero-photocatalysts containing the same cation with improved photocatalytic behavior in energy and environmental applications.