Fe/Cu MOFs of Fe²⁺-rich and Cu-doping via in situ reduction as nanozyme for peroxidase-like catalycity enhancement

Fe-MOFs of mixed valence was synthesized by a solvothermal method via the in-situ reduction of ethylene glycol (EG) pre-coordination with the proper ratio of Fe²⁺/Fe³⁺ between 0.83 and 2.46. Synchronously with copper introduction, the Fe/Cu MOFs of mixed valence (Fe/Cu-MVMOFs) was then one pot acquired to remarkably improve the affinity of Fe²⁺ and Cu⁺ to H₂O₂ and promote the conversion efficiency of Fe²⁺/Fe³⁺ via the electron transfer among Fe-Cu bimetal clusters (XPS and XRD). Hence, the maximum reaction rate of H₂O₂ with Fe/Cu-MVMOFs reached 16.65 M·s⁻¹, along with K_m as low as 0.0479 mM. H₂O₂ and glutathione (GSH) were efficiently detected, ranging from 0.25 to 60 µM and from 0.2 to 40 µM, respectively. The investigation of catalyzation selectivity and practical serum detection by Fe/Cu-MVMOFs illustrated the efficacy and efficiency, denoting Fe/Cu-MVMOFs as the promising peroxidase candidate.