Performance and mechanisms of photocatalysis of silver phosphate modified by carbon nanosheets doped with both nitrogen and boron for removal of norfloxacin

Abstract

The photocatalyst technology based on silver phosphate (Ag3PO4) has excellent oxidation ability in the degradation of antibiotic pollutants due to its appropriate energy band structure. However, the high charge recombination efficiency limits the wide application of Ag3PO4. In this study, carbon nanosheets doped with both N and B (NBNS) have excellent charge distribution. The photoactivity of Ag3PO4 was optimized by combining NBNS. After 12 min, Ag3PO4 @NBNS achieved 100% degradation of norfloxacin (NOR), 8.6 times the degradation rate of Ag3PO4 monomer. In addition, NBNS, Ag3PO4 and Ag3PO4 @NBNS were characterized by SEM, TEM, XRD, Raman and XPS. It revealed that there was an intense interface interaction between Ag3PO4 and NBNS, and a built-in electric field (BIEF) was constructed at the interface to achieve rapid separation of photogenerated charges. The DFT calculations results indicated that the doping of B and N could reduce the work function of carbon nanosheets and increase their charge density, which would promote the formation of BIEF between the interface of Ag3PO4 and NBNS. The catalytic reaction mechanism of Ag3PO4 @NBNS was proposed. This work provides a novel photocatalyst for the efficient removal of antibiotics, and sheds light on the use of carbon materials to optimize silver phosphate based photocatalyst, as well as the design of new efficient visible light catalysts.