Synergistic effect of graphitic-like carbon nitride and sulfur-based thiazole-linked organic polymer heterostructures for boosting the photocatalytic degradation of pharmaceuticals in water

A sulfur-based COF has been combined with graphitic carbon nitride (CN) in microwave-assisted synthesis to build a COF-CN heterostructure with enhanced photocatalytic activity. The prepared COF-CN were fully characterized, analyzing the textural (N2 isotherms), structural (XRD and FTIR), chemical (elemental analysis and XPS), morphological (HR-STEM), optical (DRS-UV–Vis and photoluminescence) and electrochemical properties (EIS impedance, transient photocurrent, and flat band potential). Different COF-to-CN ratios (5–25 % of COF, wt.) were explored, defining a proportion (20 %) that led to optimum activity for the photocatalytic oxidation of organic contaminants of emerging concern (CECs) due to an enhanced separation of the photogenerated charges and lower bandgap value, 2.55 vs. 2.35 eV. The performance of the optimum COF-CN was further tested for other CECs, demonstrating its benefits in comparison to the bare CN. The materials displayed acceptable reusability and stability. The mechanism of activation highlights the importance played by superoxide radicals and photogenerated holes.