MOF-Derived Bimetallic CoFe-PBA\nComposites as Highly\nSelective and Sensitive Electrochemical Sensors for Hydrogen Peroxide\nand Nonenzymatic Glucose in Human Serum

Abstract

The\nfabrication of two-dimensional (2D) metal–organic frameworks\n(MOFs) and Prussian blue analogues (PBAs) combines the advantages\nof 2D materials, MOFs and PBAs, resolving the poor electronic conductivity\nand slow diffusion of MOF materials for electrochemical applications.\nIn this work, 2D leaflike zeolitic imidazolate frameworks (Co-ZIF\nand Fe-ZIF) as sacrificial templates are in situ converted into PBAs,\nrealizing the successful fabrication of PBA/ZIF nanocomposites on\nnickel foam (NF), namely, CoCo-PBA/Co-ZIF/NF, FeFe-PBA/Fe-ZIF/NF,\nCoFe-PBA/Co-ZIF/NF, and Fe/CoCo-PBA/Co-ZIF/NF. Such fabrication can\neffectively reduce transfer resistance and greatly enhance electron-\nand mass-transfer efficiency due to the electrochemically active PBA\nparticles and NF substrate. These fabricated electrodes as multifunctional\nsensors achieve highly selective and sensitive glucose and H₂O₂ biosensing with a very wide detective linear range,\nextremely low limit of detection (LOD), and good stability. Among\nthem, CoFe-PBA/Co-ZIF/NF exhibits the best sensing performance with\na very wide linear range from 1.4 μM to 1.5 mM, a high sensitivity\nof 5270 μA mM^–1 cm^–2, a\nlow LOD of 0.02 μM (<i>S</i>/<i>N</i> =\n3), and remarkable stability and selectivity toward glucose. What\nis more, it can realize excellent detection of glucose in human serum,\ndemonstrating its practical applications. Furthermore, this material\nas a multifunctional electrochemical sensor also manifests superior\ndetection performance against hydrogen peroxide with a wide linear\nrange of 0.2–6.0 mM, a high sensitivity of 196 μA mM^–1 cm^–2, and a low limit of detection\nof 1.08 nM (<i>S</i>/<i>N</i> = 3). The sensing\nmechanism for enhanced performance for glucose and H₂O₂ is discussed and proved by experiments in detail.