Highly selective conversion of H2O2 to 1O2 via three-step electron transfer enabled by in-situ hydroxylation of atomically dispersed high-density Co−N5 sites

The traditional H2O2 oxidation treating high-salt industrial wastewater is confronted with challenges, because of the inhibition of Cl- on oxidant radical. Thus, a non-radical pathway for H2O2 removal of organic pollutants is optional. Herein, an innovative cobalt nitrogen-doped carbon (Co-N5-C) catalyst was constructed with an atomically dispersed asymmetrical high-density of Co-N5 sites and highly active intermediate Co-OH groups, achieving highly selective converting H2O2 to 1O2 through three steps electron transfer pathways. The oxidation of tetracycline by ¹O₂ accounted for 95.6 % of the total removal. H2O2 is initially activated at the Co-N5 site, which generates the active intermediate Co-OH groups. This Co-OH group then further activates H2O2, leading to the production of •O2-/•OOH. The newly produced •O2-/•OOH are instantaneously captured by neighboring Co-OH groups and subsequently converted into 1O2. These adjacent catalytic sites could effectively capture and stabilize the short-lived radicals through the distance effect. and the intermediate Co-OH group in the reaction significantly reduces the energy barrier for H2O2 conversion to •O2-/•OOH and 1O2 conversion by 0.26 eV and 11.12 eV, respectively. The efficiency of tetracycline degradation at 96 % even with the Cl- concentration as high as 7000 mg/L. •Atomically dispersed asymmetrical high-density Co-N5 catalytic site was constructed.•Adjacent Co-N5 sites adsorb and stabilize of short-live radicals by distance effect.•Intermediate Co-OH groups can high-selectively convert ·O2-/·OOH to 1O2.•The Co-N5/H2O2 degrades 96 % of TC in high-salt water though non-radical pathway.•A new conversion pathway of H2O2 to 1O2 though 3-steps electron transfer was found.