Enhancing tetracycline degradation with biomass carbon quantum dot (CQDs)-modified magnetic heterojunction CeO2-Fe3O4 under visible light

Abstract

This research investigates the synergistic enhancement of semiconductor catalysts through the incorporation of carbon quantum dots (CQDs) within CeO2-Fe3O4 Type-II heterojunction photocatalysts. Subsequent to the successful synthesis of these modified photocatalysts, a thorough assessment of their catalytic performance is conducted. Notably, the introduction of CQDs results in a 21% increase in pollutant degradation capacity compared to unmodified heterojunctions, with a remarkable removal efficiency of 96% for the target pollutant TC. Comprehensive analyses employing electrochemical impedance spectroscopy (EIS), UV–vis spectroscopy, and photocatalytic experiments provide substantial evidence for the efficacy of CQDs in enhancing light absorption properties within the CeO2-Fe3O4 heterojunction. This enhancement is attributed to a notable suppression of electron-hole pair recombination, facilitating the generation of reactive oxygen species (ROS) such as ·O2- and ·OH. This, in turn, the promotion of Ce4+/Ce3+ and Fe3+/Fe2+ cycles takes place, collectively enhancing the responsiveness of the photocatalyst to visible light. The photocatalysts demonstrate enduring catalytic and magnetic stability over five cycles, as indicated by the sustained high-performance retention. Detailed analysis using TOF-LC-MS has revealed two highly efficient degradation pathways for the for the target pollutant. The findings contribute valuable insights for advancing the performance of heterojunction photocatalysts.