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A possible mechanism for TCAA degradation in C-FeZIF/PMS system was then proposed. [Display omitted] • Graphene-based catalyst was established with Fe/Co and nitrogen doping. • 1O 2 was the main active species produced in the C-FeZIF/PMS system. • •SO 4 and •OH radicals assisted the catalytic process to a certain extent. • The combined radical and non-radical processes decomposed organic pollutants. Integrating transition-metal and nitrogen into carbon-based materials have been attracted considerable attention in peroxymonosulfate (PMS) activation, but it is a great challenge to establish strong interactions between metal species and graphene. Here, we established metal–organic frameworks (MOFs)-hydrogels which acted as templates to form a family of FeCo/graphene aerogels (C-FeCo, C-CoMIL and C-FeZIF). The C-FeZIF, which co-doped Fe/Co and nitrogen into graphene aerogel, exhibited the most regular and stable metallic frameworks, the best crystallization and biggest pore sizes; it also showed the highest efficiency and stability in PMS catalysis for trichloroacetic acid (TCAA) degradation among these aerogels. By comparative analysis on different catalysis conditions (including catalyst dosage, PMS concentrations and reaction pH), 1 g/L C-FeZIF with 4 mM of PMS reacting under pH 5 showed to be the optimum conditions with an 81.2% removal of TCAA in 160 min. Meanwhile, the C-FeZIF/PMS system also performed well in TCAA degradation within a wide pH range from 3 to 9. Radical analysis suggested that 1O 2 was the main active species produced in the C-FeZIF/PMS system, while both SO 4 •- and •OH radicals assisted the catalytic process to a certain extent. The synthesis process is environmentally friendly, easy to carry out, safe and stable with no secondary pollution, which could be scaled up easily for catalyst preparation for water treatment. [ABSTRACT FROM AUTHOR]

The stability and activity of the material are promoted by the formation of dual reaction center. • Macroscopic Fe-based graphene catalyst was facile prepared with N doping. • DFT indicated the enhanced formation of dual reaction center by N doping. • MD proved the hydrogen bonding enhanced the electron donor role of pollutant. • The N doping lowered the reduction potential of Fe(II)/Fe(III). A graphene-based hydrogel is prepared by a simple one-step method, establishing a strong dual reaction center and easy separation for efficient pollutant removal from aqueous solution. The FeOOH was grown in situ simultaneously with N doping in a graphene matrix during the self-assembly of graphene hydrogels, resulting in strong interactions in the resulting hydrogel. Density functional theory (DFT) calculation showed that the Fe–π interaction through the Fe–O–C linkage induced the formation of a dual-reaction-center around Fe and C, which was further enhanced by N doping. Furthermore, molecular dynamics (MD) simulations showed that the adsorption process was promoted due to the increase in hydrogen bonding and active sites, further enhancing the electron donor role of pollutant tetracycline for Fe(III) in the Fenton reaction. As revealed by the cyclic voltammetry results, N doping lowered the reduction potential of Fe(II)/Fe(III), which was a key factor in the Fenton reaction. In addition, high stability of the hydrogel was observed after five runs, which suggests promising applications for water treatment. [ABSTRACT FROM AUTHOR]