The generation of carbon/oxygen double defects in FeP/CoP-N-C enhanced by β particles for photic driving degradation of levofloxacin

Abstract

Carbon-based materials have been widely studied for their special electronic structure and excellent catalytic performance. In this work, polypyrrole carbon-based precursors were prepared by the polymerization of pyrrole and phytic acid with the high coordination ability of Fe and Co. Then, an FeP/CoP-N-C-X catalyst with a three-dimensional net][work structure was obtained by high-temperature calcination, which was used for the degradation of levofloxacin (LEV). The obtained results showed that FeP/CoP-N-C-700 could completely remove LEV within 40 min. XPS, Raman spectroscopy and EPR spectroscopy demonstrated the existence of a typical carbon/oxygen double-defect structure in FeP/CoP-N-C-700. XPS results shows that the percentage of oxygen defects in the O element of FeP/CoP-N-C-700 was 73.05 %. DFT calculation results shows that the d-band center of FeP/CoP-N-C-700 with carbon/oxygen double defect was −1.35 eV, while that of FeP/CoP-N-C-700 without carbon/oxygen double defect was −1.78 eV. These results indicates that the carbon/oxygen double defects could change the distribution of local electrons in FeP/CoP-N-C-700, which made it exhibit higher n-type conductivity and charge separation efficiency. After each five photocatalytic cycles, FeP/CoP-N-C-700 was treated by electron beam irradiation, and the removal rate of LEV increased from 81.2 % to 96.32 %. XPS, Raman spectroscopy and EPR spectroscopy demonstrate that carbon/oxygen double defects in FeP/CoP-N-C-700 can be regenerated by electron beam irradiation, which could greatly improve the service life of the catalyst. Furthermore, LC-MS results indicates that FeP/CoP-N-C-700 preferentially dissociates the piperazinyl group in levofloxacin and exhibits a single degradation pathway for it. This work not only provides a new idea for the regeneration of materials and the improvement of cycle performance, but also provides a new strategy for the application of electron beam irradiation in the field of photocatalysis.