BioTemplated Fe³⁺-Doped g-C₃N₄ Heterojunction Micromotors for the Degradation of Tetracycline through the Photo-Fenton Reaction

The excessive discharge of antibiotics into aquatic systems is a major issue in many countries worldwide and poses a threat to human health and the sustainable development of society. Hence, developing efficient treatment methods and purification technologies to degrade antibiotics is essential. Herein, we present the synthesis of low-cost, self-propelled tubular Fe³⁺-incorporated graphitic carbon nitride (g-C₃N₄-Fe@KF) micromotors using kapok fibers (KFs) as templates and their application as photo-catalysts for the photo-Fenton degradation of tetracycline (TC) under visible-light irradiation. The g-C₃N₄-Fe@KF micromotors moved rapidly when being propelled by oxygen bubbles generated in a hydrogen peroxide (H₂O₂) solution as a result of a photo-assisted Fenton reaction. The motion behavior of the g-C₃N₄-Fe@KF micromotors was dependent on the concentration of H₂O₂ and the length of the micromotors. The propulsion mechanism was discussed in detail. The micromotors efficiently degraded antibiotics via the photo-Fenton process. Photo-Fenton degradation efficiency was attributed to the synergistic effects of the doped Fe³⁺ and g-C₃N₄ under visible-light irradiation and self-propulsion of the micromotors. In addition, the micromotors possessed good reusability, thereby efficiently realizing multiple cycles of degradation. The current work offers an avenue for the design of micromotors, using inexpensive approaches, for various potential environmental applications.