Directional selection mechanism of single atom catalyst Co-S-C/CB regulating peroxymonosulfate radical pathway

The coordination calcination method is used to form a coordination complex between Co 2 + and thiophene, which is adsorbed on carbon black (CB) and then calcined to prepare Co-S-C/CB single atom catalyst. Co-S-C/CB could efficiently activate peroxymonosulfate (PMS) by forming Co-S 3 coordination structure and Co-S 3 is the active site for activating PMS. Electron rich region was formed on the Co atom and the Co atom could keep in a low valence state during the catalytic process and donate electrons to PMS to produce radicals (•OH and SO 4 •- ) through a single-electron-reduction. Co-S-C/CB could not only promote PMS to generate •OH and SO 4 •- , but also inhibit the generation of 1 O 2 and O 2 •- . The radical pathway has the lowest Gibbs free energy (ΔG) compared to the 1 O 2 pathway and the Co(IV)=O pathway. Therefore, Co-S-C/CB could regulate the radical pathway of PMS. •OH and SO 4 •- are mainly responsible for the removal of Rhodamine B (RhB). Co-S-C/CB could be applied to efficiently degrade various organic pollutants and has good stability. Macro preparation of Co-S-C/CB could be achieved from both the preparation process and raw material aspects.