Enhanced glucose sensing based on a novel composite Co^II-MOF/Acb modified electrode

Abstract

In this work, we demonstrate the synthesis and application of a novel Co^II-based metal-organic framework {[Co₂(Dcpp)(Bpe)_0.5 (H₂O)(μ₂-H₂O)]·(Bpe)_0.5}_n (Co^II-MOF, H₄Dcpp = 4,5-bis(4'-carboxylphenyl)-phthalic acid, Bpe = 1,2-bis(4-pyridyl)ethane) as an electrochemical sensor for glucose detection. Single-crystal X-ray diffraction analysis shows that the Co^II-MOF has a two-dimensional (2D) bilayer structure composed of Co₂ units and Dcpp^4- ligands. There are two kinds of Bpe in the structure: one serves as a bidentate ligand linking two Co1 atoms in each 2D layer; the other is just free in the lattice. The Co^II-MOF modified glassy carbon electrode (GCE) shows good electrocatalytic activity towards glucose oxidation. To further improve the catalytic activity of the electrode, a new composite of Co^II-MOF/acetylene black (Co^II-MOF/Acb) was constructed. The Co^II-MOF/Acb modified electrode exhibits enhanced sensing behavior for glucose detection. The sensing performance of Co^II-MOF/Acb/GCE with different Acb loadings was investigated in detail. The results demonstrate that Co^II-MOF/GCE with 2% Acb (Co^II-MOF/Acb-2%/GCE) exhibits the best sensing behavior, including a high sensitivity of 0.255 μA μM^-1 cm^-2 and a wide linear range of 5-1000 μM, as well as a low detection limit of 1.7 μM (S/N = 3). It's worth noting that the linear range of Co^II-MOF/Acb-2%/GCE was extended by more than ten times when compared to that of Co^II-MOF/GCE without Acb addition. In addition, Co^II-MOF/Acb-2%/GCE shows good selectivity and stability in the sensing process.