Diatomic "catalytic/co-catalytic" Fe/Mo catalysts promote Fenton-like reaction to treat organic wastewater through special interfacial reaction enhancement mechanism

Abstract

The full utilization of active sites and the effective Fe²⁺/Fe³⁺ cycling are the key problems that expand the application of iron-based Fenton-like reaction in water purification. In this paper, a novel diatomic Fe/Mo catalyst (Fe/Mo-DACs) was used to enhance the interfacial reaction mechanism with oxidant to achieve more stronger selective degradation of electron-donating organic pollutants. The availability of Fe sites during the activation of peroxymonosulfate (PMS) was enhanced by the adjacent atomic Mo sites, and the resulting special interfacial complex (Fe/Mo-DACs-PMS*) possessed higher activity, stability and selectivity (especially for electron-donating organics). The degradation rate of bisphenol A (BPA) in Fe/Mo-DACs/PMS system (0.642 min^-1) was increased by two times compared with the corresponding Fe single-atomic reaction system. Density functional theory calculation analysis further indicated that the diatomic Fe/Mo site was the true activation center of PMS, and other independent single-atom Fe sites cooperated to optimize the interface reaction mechanism (adsorption and activation) of PMS on the materials’ surface. Moreover, the promotion of Fe²⁺/Fe³⁺ cycling by Mo sites further enhanced the sustainability and adaptability of this degradation system. The atomic-level "catalytic/co-catalytic" materials are expected to broaden the design idea of heterogeneous materials and enhance the application prospect of Fenton-like reactions in water pollution control.