2D MOF with electrochemical exfoliated graphene for nonenzymatic glucose sensing: Central metal sites and oxidation potentials.

Two-dimensional metal-organic framework (MOF) has the advantages of high mass transfer speed, tunable porosity, and strong electron transfer capability. The different metal center can give MOF with good electrochemical activity because of the mulriple valence state. Here, a simple and economical method was used to successfully prepare a different metal-coordinated two-dimensional (2D) MOF with electrochemical exfoliated graphene (EG) at room temperature. As the electrode material for the nonenzymatic glucose sensor, the modified MOF/EG electrode had high electrocatalytic activity for glucose sensing. Thereinto, the nonenzymatic Co-MOF/EG sensor had nice detection performance with wide linear range (1.0-3330 μM) and minimum detection limit (0.58 μM, S/N = 3). The detection response in alkaline solution was less than 0.9 s. Most importantly, the stability and conductivity of the Co-MOF/EG were much higher than Ni-MOF/EG and NiCo-MOF/EG. The oxidation potential of Co-MOF/EG for glucose was the lowest, and the detection performance was the best at low oxidation potential of 0.2 V. The coordination unsaturated metal ion was the main active center of glucose electrocatalysis. We believe that the illustrated MOF/EG was an effective strategy for creating an active multi-phase catalyst with atomic precision.