Tunable Fe-doped porous carbon nitride nanotubes via MOF-mediated synthesis for efficient photocatalytic tetracycline degradation

Antibiotic contamination in aquatic environments poses increasing environmental and health risks, calling for efficient and sustainable remediation strategies. In this work, a metal organic framework (MOF)-mediated approach is developed to construct iron-doped carbon nitride (CN) nanotubes (Fe-CN-X, X = 0, 65, 135, 200, 270) using MIL-88A(Fe) as both an iron source and a structure-directing precursor. By regulating the amount of MIL-88A(Fe), the Fe content and structural properties of the Fe-CN-X can be precisely tuned, leading to the formation of surface-porous nanotubular structures with well-dispersed active sites. Among the prepared samples, Fe-CN-135 exhibits an optimal combination of visible-light absorption, charge separation efficiency, and surface characteristics. Under visible-light irradiation in a H 2 O 2 -assisted photocatalytic system, Fe-CN-135 achieves 99.3% degradation of tetracycline (TC) within 40 min, with a pseudo-first-order rate constant of 0.1106 min −1 . Mechanistic investigations reveal that Fe incorporation narrows the bandgap, suppresses electron-hole recombination, and promotes Fe 3+ /Fe 2+ redox cycling, leading to a • OH-dominated oxidation pathway. The catalyst also demonstrates excellent stability and effectiveness toward multiple organic pollutants. This work provides a practical and scalable strategy for designing Fe-doped CN photocatalysts through MOF-mediation and offers a unique insight for the efficient degradation of organic pollutants.