Peroxydisulfate nonradical activation on C--C engineered g-C3N4: Electron transfer mechanism for selective degradation of organic contaminants

The activation of peroxydisulfate (PDS) by g-C3N4-based catalysts has captured considerable interest; however, the oxidation prowess falls short of expectations, and the inherent processes remain enigmatic. Herein, a novel C--C engineered g-C3N4 (CCN) was successfully developed via a one-step thermal polymerization method for the activation of PDS. Our findings revealed that the CCN/PDS system selectively degraded various organic contaminants, operated effectively across a wide pH range (3-9), and maintained high performance in the presence of common water impurities. Experiments and theoretical calculations indicated that the electron transfer process (ETP) was the primary mechanism for phenol degradation. The introduction of C--C led to charge redistribution and improved conductivity in g-C3N4. This enhancement strengthened PDS adsorption at electron deficient carbon sites and bolstered electron transfer between PDS and organic contaminants. Moreover, a nonradical pathway predicated on ETP emerged when phenol, PDS, and CCN were present, propelled by differences in molecular orbital energies. This study not only deepens our understanding of PDS activation through the ETP but also introduces a novel strategy for the removal of organic contaminants from water.