CoFe-MOF nanoarray as flexible microelectrode for electrochemical detection of catechol in water samples

A simple, selective, and straightforward enzyme-free electrochemical sensor has been designed and developed using cobalt hexacyanoferrate metal-organic framework (CoFe-MOF) nanoarray. The prepared CoFe-MOF nanoarray has been successfully grown over a carbon cloth (CC) to form CoFe-MOF/CC as a flexible microelectrode for the detection of catechol. The surface of the activated CC was covered uniformly with CoFe-MOF in the form of nanoarray and exhibited double-shelled cubic morphology. The CoFe-MOF/CC nanoarray microelectrode showed a pair of well-defined redox peaks corresponding to the [Fe(CN)₆]^4-/3- redox signal. Interestingly, the fabricated nanoarray microelectrode has displayed superior peak current at lower onset potential with high electrochemical response compared to unmodified potassium hexacyanoferrate (K₃ [Fe(CN)₆]) over CC microelectrode and bare activated CC. Further, the developed CoFe-MOF/CC nanoarray microelectrode for the oxidation of catechol was examined with consecutive injections of catechol. A fast and noticeable improvement in oxidation peak current was observed, thus representing the excellent electrocatalytic oxidation of catechol at the modified nanoarray microelectrode. Besides, CoFe-MOF/CC microelectrode exhibits an excellent linear response over a concentration range from 0.005 to 2.8 mM with low detection limit (LOD) and high sensitivity of 0.002 mM (S/N = 3) and 205.99 μA/mM, respectively. Moreover, the prepared nonenzymatic sensor showed outstanding stability, acceptable reproducibility, and repeatability, along with good interference ability. Catechol in spiked water samples was successfully quantified.