Efficient degradation of Levofloxacin with magnetically separable ZnFe2O4/NCDs/Ag2CO3 Z-scheme heterojunction photocatalyst: Vis-NIR light response ability and mechanism insight

Abstract A highly efficient and easily recoverable catalyst is always desirable for practical photocatalytic applications. In this study, a magnetically separable ZnFe2O4/NCDs/Ag2CO3 Z-scheme heterojunction photocatalyst using nitrogen doped carbon quantum dots (NCDs) as solid-state electron mediators was fabricated by an easy-operated deposition-precipitation method. The prepared ZnFe2O4/NCDs/Ag2CO3 photocatalyst exhibits a promoted photocatalytic activity for Levofloxacin (LVFX) removal compared to single ZnFe2O4 and Ag2CO3, achieving 88.75% and 22.53% degradation efficiency under visible and near-infrared (NIR) light irradiation, respectively. Characterization results show that the synergistic effect of remarkable charge carrier separation efficiency and broadened solar light absorption is responsible for the enhanced photocatalytic performance. The well-matched band structures of the two semiconductors facilitate the charge transfer in Z-scheme transfer model, resulting in high charge separation rate. Simultaneously, due to the superb electron transfer character of NCDs, the introduction of NCDs can further accelerate the transfer of the photo-generated charges as solid-state electron mediators between ZnFe2O4 and Ag2CO3. Furthermore, the unique up-converted photoluminescence properties of NCDs can broaden the optical absorption of the prepared ZnFe2O4/NCDs/Ag2CO3 to NIR region, thus leading to an enhanced utilization of solar energy. This work provides a novel insight into the fabrication of novel all-solid-state Z-scheme photocatalyst based on nitrogen doped carbon quantum dots and opens new vista for the design of magnetically separable and highly efficient photocatalysts for environmental remediation.