Engineering the low-coordinated single cobalt atom to boost persulfate activation for enhanced organic pollutant oxidation

Two atomically dispersed cobalt catalysts with different nitrogen coordination numbers (denoted as Co-SA-N-x-C) were synthesized and firstly compared to activate peroxydisulfate (PDS) for bisphenol A (BPA) degradation. Theoretical calculations unveiled that lowering the Co-N coordination number from four to three can apparently increase the electron density of the single Co atom in Co-SA-N-3-C to enhance PDS conversion. The low coordinated Co-SA-N-3-C with Co-N-3 coordination structure displays a high specific activity of 0.067 L min(-1) m(-2), which is 1.31 times greater than that of Co-SA-N-4-C with normal Co-N-4 configuration (0.051 L min(-1) m(-2)) in PDS activation. Electron paramagnetic resonance (EPR) measurements and quenching tests confirmed the primary role of sulfate radical (SO4 center dot-) in BPA oxidation over Co-SA-N-3-C with PDS. Moreover, Co-SA-N-3-C delivers favorable durability for PDS activation and potential practicability for realistic wastewater remediation. These findings provide a novel and useful avenue to coordination number modulation of SACs for wider environmental applications.