Cyano group modified graphitic carbon nitride with K intercalation for sustainable photodegradation of pharmaceutical waste

Background: Pharmaceutical and personal care product (PPCP) pollutants in the aquatic environment are worrying as the conventional treatment processes are challenging due to the low molecular weight and strong hydrophilicity of PPCPs. The nontoxic g-C₃N₄ is highly promising for sustainable environmental remediation but suffers from key bottlenecks of rapid charge recombination and poor light absorption capacity. Methods: Potassium-intercalated g-C₃N₄ (K-CN) was prepared by a facile alkali and heat treatment with varying KOH concentrations. Significant findings: The photocatalytic performance of g-C₃N₄ was significantly improved where the best acetaminophen degradation efficiency and the corresponding pseudo-first-order rate constant over 1.2K-CN were 2.51-fold and 5.29-fold higher relative to pristine g-C₃N₄. This is ascribed to the formation of cyano group and intercalation of K atoms in g-C₃N₄, which were corroborated through various characterization techniques to reveal the greater light absorbance, narrowed band gap, effective charge transfer, and suppressed electron-hole recombination. Furthermore, superoxide anions (•O₂⁻) were verified to be the leading reactive species for acetaminophen photodegradation, followed by photoinduced holes (h⁺) and hydroxyl (•OH) radicals. Overall, this work provides a simple yet effective approach to boost the performance of g-C₃N₄ and is anticipated to initiate further research in sustainable pharmaceutical wastewater degradation.