Construction of up-converting fluorescent carbon quantum dots/Bi20TiO32 composites with enhanced photocatalytic properties under visible light

Abstract

To achieve the efficient utilization of solar light energy, novel carbon quantum dots (CQDs) modified Bi20TiO32 photocatalysts were prepared with different CQDs contents. The obtained photocatalysts were characterized by XRD, FT-IR, XPS, SEM, HRTEM, photoluminescence (PL) spectra, transient photocurrent and electrochemical impedance spectroscopy (EIS). The results showed that the CQDs were uniformly deposited on the surface of Bi20TiO32. The as-prepared CQDs/Bi20TiO32 composites were capable of utilizing both the visible and near-infrared light due to the active role of the carbon nanodots as up-converting photo-sensitizers. By the LC–MS-MS analysis, the herbicide isoproturon molecular could be firstly degraded to several intermediates and then completely mineralized. The CQDs/Bi20TiO32 photocatalysts with a CQDs content of 1% exhibited the optimum photocatalytic activity and could degrade 98.1% of isoproturon within 48h. Its degradation rate constant was approximately 4.3 times higher than that of pure Bi20TiO32. The main active species in the photo-degradation process was h+ and O2−. To further study the recycle ability of CQDs/Bi20TiO32 photocatalyst, the PAN supported CQDs/Bi20TiO32 nanofiber mat was prepared by coaxial electrospinning method. The composite nanofiber materials showed good photocatalytic activity and recyclability, which had potential applications in water/air purification field and biochemical protective clothing.