Unraveling the co-catalytic mechanism in Fenton-like reaction with diatomic Fe/Mo catalysts: Accelerating the Fe(Ⅱ)/Fe(Ⅲ) conversion and PAA efficient activation.

This study attempts to address the technical challenge of poor valence cycling and low activation efficiency of Fe-based catalysts in peracetic acid (PAA)-based advanced oxidation processes (AOPs) for organic micropollutant treatment. The successful synthesis of the Mo doped Fe-based catalyst (Fe1Mo2@CN) achieved efficient PAA activation and rapid degradation of organic micropollutants. Mechanistic studies showed that both radical pathway (•OH and CH3COOO•) and non-radical pathway (1O2) synergistically contributed to bisphenol A (BPA) degradation. Results revealed that the presence of Mo promoted low-valent Fe species generation and accelerated Fe(Ⅱ)/Fe(Ⅲ) conversion, while enhancing the surface adsorption capacity and electron transfer capability of Fe1Mo2@CN toward PAA dramatically. Compared to the Fe@CN/PAA system, the Fe1Mo2@CN/PAA system exhibited lower energy barriers in the generation processes of both radicals and non-radical, facilitating the production of ROS and ensuring efficient activation of PAA. Meanwhile, the reduced eco-toxicity after treatment and the complete removal of BPA in continuous-flow experiment indicated that this system possessed high environmental safety and promising practical applicability. This work established a metal doping strategy for designing high performance Fe-based catalysts for PAA activation, providing critical theoretical guidance for advancing the practical implementation of PAA-based AOPs in water treatment applications.