Cation−π structure inducing efficient peroxymonosulfate activation for pollutant degradation over atomically dispersed cobalt bonding graphene-like nanospheres

Orbital interaction involving metal cation−π is an important form for electron transfer regulation. To accelerate the interfacial electron transfer of peroxymonosulfate (PMS) activation for water treatment, we report a new strategy through bonding atomically dispersed cobalt with nanospheric C-based graphene-like structures (SACo-NGs) to form metal cation−π structure, driving rapid and directional transfer of the electrons of pollutants to PMS on the catalyst surface. The catalyst SACo-NGs is synthesized by an enhanced hydrothermal-sintering method and the formation of metal cation−π structure is demonstrated by X-ray absorption fine structure (EXAFS), X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance spectroscopy (EPR) and Raman spectroscopy. It is found that Co−π structures (Co2+-N-Cπ) play a key role for the efficient activation of PMS, which results in pollutants being greatly removed in a few minutes. During the reaction, pollutants can donate electrons for the system through π−π interaction accompanying by the direct oxidative degradation of pollutants. The obtained electrons are quickly transferred to the atomically dispersed cobalt sites through the formed cation−π structure, which promotes the activation of PMS. This is a successful practice in the field of PMS activation using cation−π structure to accelerate electron transfer and achieve rapid degradation of pollutants.