Synthesis and properties of visible light responsive g-C3N4/Bi2O2CO3 layered heterojunction nanocomposites

Abstract

Visible light responsive g-C₃N₄/Bi₂O₂CO₃ layered heterojunction nanocomposites were prepared by two methods, self-assembly and chemical precipitation. X-ray diffraction (XRD), UV-Vis spectroscopy, N₂ adsorption, Scanning electron microscopy (SEM), electrochemical impedance spectra (EIS) and X-ray photoelectron spectroscopy (XPS) were used to characterize the prepared catalysts. The results indicated that the preparation method does not influence the crystal phase, morphology and optical property of the obtained nanocomposites, but affects the interaction strength between g-C₃N₄ and Bi₂O₂CO₃, leading to an obvious difference in the separation rate of photogenerated electrons and holes. The activities were tested in photocatalytic rhodamine B (RhB) and phenol degradation under visible light. The g-C₃N₄/Bi₂O₂CO₃ nanocomposite with a stronger interaction showed the better activity. The ˙O₂⁻ radicals are responsible for the degradation of RhB. No obvious decrease in activity was observed for g-C₃N₄/Bi₂O₂CO₃ nanocomposites prepared by the self-assembly method after three cycles. The significant enhancement of the photocatalytic activity was attributed to the high charge-separation efficiency due to the hybrid effect of RhB, Bi₂O₂CO₃ and g-C₃N₄. The self assembly method assisted by CTAB leads to tight decoration of Bi₂O₂CO₃ nanoparticles on g-C₃N₄ sheets facilitating intimate contact and formation of a stable heterojunction.