Mechanical Insight into Direct Singlet Oxygen Generation Pathway: Pivotal Role of Fen4 Sites and Selective Organic Contaminants Removal

Singlet oxygen (1O2) is an essential active species for selective oxidation of organic compounds. However, the generation mechanism of 1O2 in peroxymonosulfate (PMS) based advanced oxidation process is still disputable. In this work, graphitic carbon matrix supported single iron atom and iron nanoclusters configurations were synthesized via calcinating Prussian blue, which showed admirable catalytic efficiency towards bisphenol A oxidation even under high salinity conditions. 1O2 directly generated on Fe-pyridinic N moiety bonded with terminal O of PMS (HSO5-) was proposed as predominant reactive species. Experimental results and theoretical analysis further detailly demonstrated the evolutionary pathway of 1O2 formation, which occurred through the interaction of two O atoms from adsorbed PMS, accompanying two HSO4- molecules generation with the lowest energy barrier. This study firstly proposed novel insights into direct 1O2-modulated mechanism via Fe-N4 configuration, providing essential atomic-scale understanding of FeNx/PMS based Fenton-like system and practical application towards efficient environmental remediation.