Efficient light-free activation of peroxymonosulfate by carbon ring conjugated carbon nitride for elimination of organic pollutants

Abstract

Realizing graphitic carbon nitride (g-C3N4) being active in light-free heterogeneous catalysis remains a big challenge as a result of its inertness if not irradiated. Herein, we demonstrate the successful construction of g-C3N4-based in-plane heterostructure by intimately connecting g-C3N4 framework with carbon ring via strong π-conjugated bonds, which regulates the electron density distribution of the g-C3N4 composite. The optimized carbon ring conjugated carbon nitride (CCN0.1) with porous architecture and modulated electronic structure delivers admirable catalytic performance in peroxymonosulfate (PMS) activation without the need of light, with its specific activity being significantly superior to nonmetal-doped g-C3N4 and comparable to part of active nitrogen-doped carbon materials. Experimental data and theoretical results revealed the two domains of g-C3N4 with higher electron density and the conjugated carbon ring with lower electron density in CCN0.1 involve in PMS conversion accounting for PMS reduction and oxidation, respectively, which simultaneously facilitates dissolved oxygen reduction over the g-C3N4 field. Moreover, CCN0.1 shows robust stability in PMS activation, and meanwhile, the CCN0.1/PMS system exhibits potential effectiveness in actual industrial wastewater remediation. This work expands the range of nonmetallic g-C3N4-based materials for light-free activation of persulfate and deepens the mechanistic understanding of persulfate conversion process for wider environmental applications.