Understanding roles of π electron delocalization and hybridization transformation of nanodiamond in carbocatalysis-mediated persulfate activation regime

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Carbocatalysis-mediated persulfate (PS) activation for micropollutant abatement has gained extensive attention, commonly concentrating on carbocatalysts surface chemistry but overlooking intrinsic characteristics, e.g., electron orbital and hybridization configurations. Herein, nanodiamond (ND) composed of sp3-hybridized carbon undergoes annealing processes from 300 to 1500 °C, to improve catalytic performances in PS activation significantly toward degrading bisphenol A (BPA), benefiting from ND hybridization transformation from sp3 to sp2 with increasing chemical and electrical activities via converting σ to π electrons and delocalizing π electrons with increasing annealing temperature. NDs with sp3 hybridization activate PS to drive direct electron transfer pathways, serving as electron mediators to facilitate PS to deprive electrons from BPA. Localized and delocalized π electrons were responsible for the generation of reactive surface-bound complexes and singlet oxygen, respectively. The controllability of ND hybridization structure provides a feasible strategy to regulate PS activation pathways based on the reactivity affinity of reactive species toward micropollutants.