Nitrogen-doped hollow carbon spheres as efficient metal-free peroxymonosulfate activator for degradation of organic pollutant

Developing effective metal-free catalytic materials via constructing copious surface-exposed active sites to promote peroxymonosulfate (PMS) activating for degradation of hazardous organics is highly desirable toward practical application. In this study, we report the utilization of N-functionalized hollow carbon spheres (N-HCS) as efficient PMS activator for Rhodamine B (RhB) degradation. Results indicate that N-doping of hollow carbon spheres can introduce an abundance of pyridinic N and C--O sites, which serve as catalytically active sites for PMS activation toward RhB degradation. The fabricated catalyst exhibits excellent performances with a degra-dation efficiency of 100 % and a rate constant of 0.0566 min-1 for RhB degradation under optimal conditions. Besides, the developed N-HCS catalyst displays a good reusability, maintaining a high degradation efficiency after the 5th run. Quenching tests and electron spin resonance characterization results reveal the coexistence of radical and non-radical degradation pathways, and SO4 center dot- and 1O2 are demonstrated as the dominant reactive oxygen species. This architecture integrated surface microenvironment engineering strategy can be extended to regulate the degradation performance of carbon-based materials for PMS activation toward removing other organic pollutants.