An electrochemical sensor for H2O2 based on a new Co-metal-organic framework modified electrode

In this work, a new Co metal-organic framework (Co(pbda)(4,4-bpy)·2H2O]nCo-MOF) (bpy = 4,4-bipyridine; H2pbda = 3-(pyridine-3-yloxy)benzene-1,2-dicarboxylic acid) was synthesized under hydrothermal conditions and then applied as the active materials for high performance hydrogen peroxide sensor. Single-crystal X-ray analysis reveals a three-dimensional supramolecular architecture with a uninodal 4-connected net with the gis topology. The cyclic voltammogram of the Co-MOF modified GC electrode shows a pair of reduction peaks at ca. −0.40 V in 0.1 M NaOH solution corresponding to CoIII-MOF/CoII-MOF couple. The amperometric response demonstrates the high electrocatalytic activity of the Co-MOF modified GC electrode towards H2O2 reduction with a wide linear range from 5 μM to 9.0 mM, a low detection limit of 3.76 μM and a high sensitivity of 83.10 μA mM−1 cm2 at an applied potential of −0.40 V. Moreover, the favourable selectivity and long-term stability were also obtained. Additionally, it was found that Co-MOF possessed highly efficient intrinsic peroxidase-like activity so that it could catalyze H2O2 to produce hydroxyl radical, which oxidized peroxidase substrate (terephthalic acid) to produce colour. Thus, this new Co-MOF has a great potential for applications in H2O2 electrochemical detection.