Novel 0D-1D-2D nanostructured MCN/NCDs recyclable composite for boosted peroxymonosulfate activation under visible light toward tetracycline degradation

In this study, a novel nitrogen modified carbon quantum dots (NCDs) decorated graphite carbon nitride /molybdenum (Mo) heterojunction photocatalyst (MCN/NCDs) was obtained by in-situ calcination and physical deposition, and applied as peroxymonosulfate (PMS) activators for tetracycline (TC) removal under visible light. It was found that the MCN/NCDs as PMS activation catalyst exhibited outstanding removal efficiency under visible light assistance and nearly 98.4% of TC was degraded within 60 min. The analysis data of photochemistry demonstrated that the introduction of NCDs could significantly improve the visible-light utilization, narrow the band gap and increase the separation of photogenerated electron-hole pairs. The results of radical capture experiment and electron spin resonance test (ESR) suggested that the order of active species contributing to TC degradation in vis/PMS/MCN/NCDs system was O 2 –  > h + > OH >  1 O 2  > SO 4 − . Moreover, the MCN/NCDs composite exhibited excellent stability with over 98% activity retention for 5 cycles and superior catalytic efficiency in four real water matrix. Finally, the underlying degradation mechanism and toxicity assessment were proposed in detail. This work provided a new perspective on the design of excellent activity g-C 3 N 4 composite catalysts and elucidated a promising potential strategy for efficient contaminated water treatment via PMS activation process.