Experimental and DFT insights into the visible-light driving metal-free C3N5 activated persulfate system for efficient water purification

[Display omitted] •Metal-free C3N5 showed enhanced visible-light-driven PMS/PDS activation.•Efficient pollutant degradation and water disinfection was achieved.•Narrower bandgap, richer defects, and higher N ratio make higher PMS/PDS activation. Although Fenton-like processes have been widely applied to treat emerging micropollutants (EMs) in wastewater, conventional activators used to activate peroxymonosulfate (PMS) or peroxydisulfate (PDS) still suffer from the problems of metal leaching and limited catalytic stability for practical applications. Herein, metal-free C3N5 was synthesized and employed as an activator for PMS activation. With the aid of visible light, C3N5 exhibited an excellent PMS activation capacity for EMs degradation, even better than popular C3N4. This is because C3N5 can harvest more visible light, prolong the lifetime of photogenerated carriers, and enhance PMS adsorption by more N active sites. Additionally, efficient EMs degradation and water disinfection were also achieved by visible light driving C3N5 activated PDS. This work demonstrates a new metal-free material for environmental-friendly advanced oxidation processes for the efficient water purification.