Facile Formation of Bi₂O₂CO₃/Bi₂MoO₆ Nanosheets for Visible Light-Driven Photocatalysis

Bi₂O₂CO₃/Bi₂MoO₆ heterojunction catalysts were prepared by treating Bi₂MoO₆ sheets with aqueous NaHCO₃ solutions at room temperature. All the Bi₂O₂CO₃/Bi₂MoO₆ heterojunctions exhibited higher activities than pristine Bi₂MoO₆ in the photocatalytic degradation of rhodamine B (RhB), methyl orange, and ciprofloxacin under visible-light irradiation, and the most active photocatalyst was found to be the one with a C/Bi molar ratio of ∼1/2.3. Relevant samples were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, N₂ adsorption-desorption, Fourier transform infrared spectroscopy, and UV-vis spectroscopy. The higher activity of Bi₂O₂CO₃/Bi₂MoO₆ than pristine Bi₂MoO₆ is explained by the enhanced separation and transfer of photogenerated electron/hole pairs, as verified by transient photocurrent densities, photoluminescence spectroscopy, and electrochemical impedance spectroscopy. Photogenerated holes (h⁺) and superoxide radical anions (^•O₂ ^-) were found to be the main active species. The good reusability of Bi₂O₂CO₃/Bi₂MoO₆ was testified by cycling degradation of RhB and tetracycline hydrochloride.