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 CoSA-Nx-C) were synthesized and firstly compared to activate peroxydisulfate (PDS) for bisphenol A (BPA) degradation. Theoretical calculations unveiled that lowering the CoN coordination number from four to three can apparently increase the electron density of the single Co atom in CoSA-N3-C to enhance PDS conversion. The low-coordinated CoSA-N3-C with CoN3 coordination structure displays a high specific activity of 0.067 L min1 m2, which is 1.31 times greater than that of CoSA-N4-C with normal CoN4 configuration (0.051 L min1 m2) in PDS activation. Electron paramagnetic resonance (EPR) measurements and quenching tests confirmed the primary role of sulfate radical (SO4•−) in BPA oxidation over CoSA-N3-C with PDS. Moreover, CoSA-N3-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.