High‐Quantum‐Yield Carbon Nitride Quantum Dots via Water Vapor Intercalation‐Exfoliation for Efficient Tetracycline Hydrochloride Degradation

Abstract Graphitic carbon nitride (g‐C 3 N 4 ) has demonstrated potential applications in addressing energy shortages and preserving water ecosystem stability due to its high efficiency in degrading antibiotics. However, the mediocre catalytic performance of bulk g‐C 3 N 4 is attributed to inefficient carrier transport and a high complexation rate of photogenerated electron‐hole pairs. Herein, a method for fabricating carbon nitride quantum dots (CNQDs) via water vapor intercalation‐exfoliation during high‐temperature thermo‐polymerization of g‐C 3 N 4 is proposed. The resulting CNQDs exhibit a high quantum yield (49.8%), reduced bandgap, and pH‐dependent properties. Structural nitrogen defects and doping of oxygen‐containing functional groups contribute to improved charge‐transfer efficiency and enhanced photooxidation capacity of CNQDs from water vapor intercalation‐exfoliation. Remarkably, the optimal CNQDs‐650 demonstrates excellent photodegradation activity of tetracycline hydrochloride (TCH), ≈2.7 times higher than that of g‐C 3 N 4 . Additionally, the photo degradation pathways of TCH are proposed based on identified intermediates. This study introduces a new and efficient approach to synthesizing CNQDs with high photocatalytic performance.