Simultaneous morphology control and defect regulation in g-C3N4 for peroxymonosulfate activation and bisphenol S degradation

Nonmetallic catalysts that can effectively activate peroxymonosulfate (PMS) under visible light are of great interest for removing endocrine disruptors in water. In this study, a simple one-step strategy was developed to synthesize two-dimensional (2D) nitrogen-deficient graphitic carbon nitride (CNX) for visible-light activation of PMS (CNX/PMS/Vis). The CNX-3/PMS/Vis system could degrade bisphenol S (BPS) more efficiently (90.37 %, 90 min) than graphitic carbon nitride (g-C3N4)/PMS/Vis (58.36 %, 90 min). Experiments and density functional theory calculations showed that the improved catalytic performance was due to the 2D nitrogen defect structure in the modified g-C3N4. Such structure reduced the work function, inhibited the recombination of photogenerated carriers, enhanced the adsorption energy between g-C3N4 and PMS, and strengthened the synergy between photocatalysis and PMS activation. Radical quenching and electron paramagnetic resonance experiments demonstrated that the main mechanism of BPS degradation involved free radicals and nonradicals, wherein 1O2, O2•-, and h+ were the main reactive oxygen species, and •OH and SO4•- were the secondary species. In addition, CNX-3/PMS/Vis system had strong anti-interference ability to the environmental background and a wide range of operating pH. To summarize, herein we developed a low-cost and green nonmetallic catalyst to cooperate with PMS-based advanced oxidation technology via photocatalysis, providing new ideas to remove organic pollutants in water.