Mechanism of peroxymonosulfate activation by nanoparticle Co@N–C: Experimental investigation and theoretical calculation

The release of organic dyes, such as Rhodamine B (RhB), into industrial wastewater has led to significant issues with color pollution in aquatic environments. Herein, we prepared a cobalt nanoparticles (NPs)-based catalyst with the nitrogen-doped carbon-support (Co@N–C) for effective PMS activation. The Co@N–C/PMS system demonstrated the excellent catalytic activity of Co@N–C for activating PMS, achieving nearly 100% degradation of RhB. Singlet oxygen (1O2) and sulfate radicals (SO4•-) were dominant reactive oxygen species for RhB degradation. Density functional theory (DFT) calculations substantiated that the production of 1O2 commenced with the initial generation of *OH through hydrogen abstraction from PMS, culminating in the direct release of oxygen to form 1O2 (PMS→*OH→O*→1O2). The generation of SO4•- was attributed to electron transfer to PMS from the surface of Co NPs (Co0→Co2+→Co3+) and the C–N shell (Co2+→Co3+). The research findings provided new insights into the development of Co-based heterogeneous catalysis for advanced oxidation of refractory organic pollutants in wastewater treatment.