Unraveling the synergistic and coupling effects between catalyst, oxygen, and organics for highly efficient mineralization of refractorily aromatic rings

Abstract

Self-producing of H2O2 and their activation into •OH over a pronged graphene-like carbon nitride (Fe@CN/WO3) for efficiently removing organics from water were investigated. Experimental and theoretical analyses revealed an S-scheme with an inner electric field as strong as 1.11 V in separating e-h+, and a strong synergy of photocatalysis and Fenton process. Fe@CN/WO3 exhibited 15 and 11 times the H2O2-activation and hydroxyl radical (•OH)-generation rates than those of pristine CN, respectively, and their performance in degrading organics is dynamically comparable to some heterogeneous Fenton. This work reveals a most reasonable process for decontaminating organics under solar empowerment and atmospheric oxygenation specified as: i) photoelectrons reduced O2 to superoxide anion radical (•O2−) and cycled ≡Fe3+/≡Fe2+; ii) •O2− deprotonated functional groups of TC-HCl, facilitating two-electron O2 reduction into H2O2; iii) ≡Fe2+ efficiently activated the produced H2O2 into •OH; iv) •OH compensated for the weakness of •O2− in disassembling refractorily aromatic rings, helping to achieve unparalleled efficiency in mineralizing organic contaminants. Particularly, success is unraveling the photo-self Fenton process between catalyst-oxygen-organics.