Enhanced Photocatalytic Tetracycline Degradation Using Nb₂C/g-C₃N₅ Nanoheterostructures Activated by...

The degradation of pollutants represents a critical approach to addressing urgent energy and environmental challenges. Although heterojunction catalysts possess designable electron transfer pathways that are advantageous for wastewater treatment, maintaining both high degradation activity and good recyclability remains a major challenge. In this study, a Nb₂C MXene/graphitized carbon nitride (g-C₃N₅) heterojunction nanocomposite was synthesized via an electrostatic self-assembly method. Morphological investigations utilizing scanning and transmission electron microscopy demonstrated the preservation of the layered nanostructures of MXene, while g-C₃N₅ nanoparticles coalesced to form nanosheets. The degradation efficiency under visible light was carefully tested under various conditions, including seven distinct mass ratios of Nb₂C to g-C₃N₅, co-existing ions, initial concentration, pH, catalyst dose, and peroxymonosulfate (PMS) concentration. The results showed that the removal efficiency of tetracycline (TC) reached 90.2%, and the influence of coexisting ions followed the order: NO₃ ^- > H₂PO₄ ^- > Cl^- > SO₄ ^2-. Based on electron paramagnetic resonance (EPR) spectra and radical trapping studies, singlet oxygen (¹O₂) and superoxide radicals (·O₂ ^-) were identified as the dominant reactive species. Nb₂C/g-C₃N₅ constructed Schottky heterojunction; the suggested electronic band structure efficiently prevents electron and hole recombination in photocatalytic reactions. This study's findings advance the creation of extremely effective PMS-activated photocatalytic systems with significant promise for wastewater purification.