Single-Atom Cobalt Catalysts Encapsulating Cobalt Nanoparticles with Built-In Electric Field for Ultrafast and Lasting Peroxymonosulfate Activation

Cobalt single-atom catalysts (Co-SAs) are rising stars in persulfate chemistry for their well-defined coordination, reduced metal usage, and exceptional activity. However, the simultaneous formation of cobalt nanoparticles (Co-NPs) with Co-SAs raises questions about their complex interplay and synergy in catalysis. In this study, we synthesized Co-SAs-encapsulated Co-NPs (CoNP@NC/Co-SA) using the laser-induced carbonization strategy of high entropy synthesis technology. The results show that 93.23% of phenol can be removed in 15 min and 91.60% in 3 min in the CoNP@NC/Co-SA/PMS system. Simulation results showed that Co-NPs fine-tune the electronic structure of Co-SA sites, optimizing PMS adsorption and activation to generate confined reactive species. The surface-activated PMS-catalyst complex directly attacked adsorbed pollutants on the catalyst surface via an electron-transfer regime. CoNP@NC/Co-SA catalyzes PMS oxidation through a nonradical pathway with high selectivity toward target organics. The findings emphasize the synergistic effect of Co-SAs and Co-NPs in promoting Fenton-like catalysis, enlightening the rational design of advanced composite materials via synergistic molecular and interfacial engineering for fast and long-lasting catalytic oxidation. At the same time, this work provides insights into the electronic structure regulation of metal centers at the atomic level.