Synthesis and testing of carbon quantum dots loaded 2D Bi2MoO6 for efficient Hg0 photocatalytic removal

Carbon quantum dots (CQDs) was prepared and supported on 2D Bi₂MoO₆ by hydrothermal method to prepare 2D Bi₂MoO₆/CQDs composite photocatalyst with up-conversion luminescence (UPCL) characteristics. The properties of 2D Bi₂MoO₆/CQDs were characterized by a series of characterization tools. Then, 2D Bi₂MoO₆ and 2D Bi₂MoO₆/CQDs catalysts were applied to photocatalytic Hg⁰ removal. The experimental results show that Hg⁰ removal efficiency of 2D Bi₂MoO₆/CQDs increased from 30.5% to 80.1% under visible light and from 7.2% to 26.4% under near-infrared light compared with 2D Bi₂MoO₆. The photostability test shows that 2D Bi₂MoO₆/CQDs nanocomposites could maintain high photostability after five photoreaction cycles. UPCL test proved that CQDs had the ability to absorb infrared light and emit visible light, thus expanding the light utilization range of composite catalyst. Moreover, in N₂+6%O₂+12%CO₂+NO atmosphere, Hg⁰ removal efficiency of 2D Bi₂MoO₆/CQDs first dropped and then raised with the increase of NO concentration due to the simultaneous reduction and oxidation of NO in the system. Finally, the ESR test shows that the modification of CQDs could not only enhance light absorption rang of photocatalyst, but also promote the transfer of photogenerated carriers on the catalyst surface, thereby enhancing the photocatalytic Hg⁰ removal capability of the 2D Bi₂MoO₆/CQDs catalyst.