zhangchaojun

In-situ epitaxial growth is a fascinating strategy to nicely couple two low dimensional semiconductors as highly efficient composite photocatalysts. Meanwhile, organic contaminants in the photocatalytic process are usually decomposed into greenhouse gas (CO₂) that can’t be reused. Herein, we reported a green full spectrum light (UV, visible and NIR lights) induced epitaxial growth strategy to synthesize highly efficient Bi₂O₄/Bi₂O₂CO₃ heterostructure photocatalyst by reusing waste carbon source, in which one-unit-cell Bi₂O₂CO₃ layers (1.0 nm) in-situ grew on the surface of Bi₂O₄ nanocrystals during the photocatalytic degradation of rhodamine B (RhB) or phenol. More importantly, ¹³C nuclear magnetic resonance (NMR) spectroscopy confirmed that the carbon element in Bi₂O₂CO₃ was from the photocatalytic degradation of organic contaminations. Furthermore, density functional theory (DFT) calculations confirm that the Bi₂O₄ nanocrystals with exposed {-101} facets have the larger percentage of undercoordinated Bi atoms, which provided favorable conditions for the in-situ epitaxy of Bi₂O₂CO₃ during the photocatalytic reaction. Additionally, the increased charge density near the Fermi level resulted in improved photoresponsivity of Bi₂O₄/Bi₂O₂CO₃ composite and the coalescence of Bi₂O₄ and Bi₂O₂CO₃ could favor the travel of photogenerated carriers from one to another owing to the close work functions for Bi₂O₄ (4.295 eV) and Bi₂O₂CO₃ (4.410 eV). As we expected, the Bi₂O₄/Bi₂O₂CO₃ composite presented higher photocatalytic activity for phenol and ciprofloxacin (CIP) degradation than pure Bi₂O₄ nanocrystals. The possible degradation pathway of CIP in aqueous solution and photocatalytic mechanism of Bi₂O₄/Bi₂O₂CO₃ composite were also proposed based on liquid chromatography mass spectrometer (LC–MS) analysis and experimental results. This work provides a green strategy for designing highly efficient photocatalysts.