Lignin-Regulated Carbon/Cobalt Co-Doped Graphite carbon nitride with synergistically enhanced Photo-PMS activation for efficient organic Pollutant degradation

Peroxymonosulfate (PMS) activation via heterogeneous photocatalysis is effective for degrading refractory organic pollutants. However, conventional graphitic carbon nitride (g-C 3 N 4 ) is limited by narrow light absorption and inefficient charge separation. Herein, leveraging the metal-chelating ability of biomass sourced lignin, C, Co co-doped g- C 3 N 4 (LCN-Co) was successfully synthesized with enhanced photocatalytic and PMS activation performance. In the photo-PMS system, LCN-Co exhibited superior degradation of tetracycline hydrochloride (TC), with a rate constant 4.04, 2.90, and 2.35 times higher than MCN, LCN, and MCN-Co. Mechanistic studies revealed that lignin-derived carbon enhanced light harvesting and synergistically promoted charge separation with Co, thereby accelerating reactive oxygen species generation, PMS activation, and the Co 2+ /Co 3+ redox cycle. Moreover, lignin chelation effectively suppressed Co aggregation and leaching, resulting in excellent reusability. This work demonstrates a lignin-enabled dual-regulation strategy for improving light absorption and metal stabilization in g-C 3 N 4 -based photocatalysts.