Plasmonic Ag Nanoparticle-Loaded n-p Bi(2)O(2)CO(3)/α-Bi(2)O(3) Heterojunction Microtubes with Enhanced Visible-Light-Driven Photocatalytic Activity

In this study, n-p Bi(2)O(2)CO(3)/α-Bi(2)O(3) heterojunction microtubes were prepared via a one-step solvothermal route in an H(2)O-ethylenediamine mixed solvent for the first time. Then, Ag nanoparticles were loaded onto the microtubes using a photo-deposition process. It was found that a Bi(2)O(2)CO(3)/α-Bi(2)O(3) heterostructure was formed as a result of the in situ carbonatization of α-Bi(2)O(3)microtubes on the surface. The photocatalytic activities of α-Bi(2)O(3) microtubes, Bi(2)O(2)CO(3)/α-Bi(2)O(3) microtubes, and Ag nanoparticle-loaded Bi(2)O(2)CO(3)/α-Bi(2)O(3) microtubes were evaluated based on their degradation of methyl orange under visible-light irradiation (λ > 420 nm). The results indicated that Bi(2)O(2)CO(3)/α-Bi(2)O(3) with a Bi(2)O(2)CO(3) mass fraction of 6.1% exhibited higher photocatalytic activity than α-Bi(2)O(3). Loading the microtubes with Ag nanoparticles significantly improved the photocatalytic activity of Bi(2)O(2)CO(3)/α-Bi(2)O(3). This should be ascribed to the internal static electric field built at the heterojunction interface of Bi(2)O(2)CO(3) and α-Bi(2)O(3) resulting in superior electron conductivity due to the Ag nanoparticles; additionally, the heterojunction at the interfaces between two semiconductors and Ag nanoparticles and the local electromagnetic field induced by the surface plasmon resonance effect of Ag nanoparticles effectively facilitate the photoinduced charge carrier transfer and separation of α-Bi(2)O(3). Furthermore, loading of Ag nanoparticles leads to the formation of new reactive sites, and a new reactive species ·O(2)(−) for photocatalysis, compared with Bi(2)O(2)CO(3)/α-Bi(2)O(3).