Atomically\nDispersed Cobalt Anchored on Hollow Tubular\nCarbon Nitride Mediates Direct Electron Transfer and Oxygen-Related\nActive Species Path for Activation of Permonosulfate

Atomically dispersed catalysts anchored on nitrogen-rich\nsubstrates\npresent promising application potential for the persulfate-based advanced\noxidation process. Nevertheless, efficient activation efficiency and\na clear activated mechanism of persulfate remain challenging in carbon\nnitride-based single-atom catalysts (SACs). To these, combined with\nthe regulation strategy of metal–ligand section and carrier’s\narchitecture, an atomically dispersed Co single-atom catalyst anchored\non regular hollow tubular carbon nitride (Co/TCN SAC) herein was devised\nand utilized to activate permonosulfate. As a result, Co/TCN SACs\nshow excellent catalytic performance for the degradation of common\nantibiotics. Combined with X-ray absorption fine structure and theory\ncalculation, it is confirmed that superficially anchored CoO<sub>3</sub> sites of the Co<sub>2</sub>N<sub>2</sub>O<sub>2</sub>–CoO<sub>3</sub> unit are the catalytic active center for peroxymonosulfate\n(PMS) activation. The electrochemical test and in situ electron paramagnetic\nresonance results demonstrate radical (SO<sub>4</sub><sup>•–</sup> and <sup>•</sup>OH) and nonradical (electron transfer process and <sup>1</sup>O<sub>2</sub>) paths contributing to the superior catalytic performance.\nIn addition, the catalyst exhibits high reaction efficiency and structural\nstability considering water quality parameters. Finally, a continuous\nand efficient device was operated on a laboratory scale, which exhibited\nsatisfactory efficiency in continuously removing electron-rich antibiotics\nsuch as tetracycline. This work reveals the atomic-level modulation\nof cobalt atomic sites on hollow tubular carbon nitride and their\nstructure–activity relationship with persulfate activation.