A novel nitrite sensor fabricated through anchoring nickel-tetrahydroxy-phthalocyanine and polyethylene oxide film onto glassy carbon electrode by a two-step covalent modification approach

In this paper, we present a two-step covalent modification approach to fabricate a novel nitrite sensor through anchoring nickel-tetrahydroxy-phthalocyanine (NiPc(OH)(4)) and polyethylene oxide (PEO) onto a glassy carbon electrode (GCE). The surface morphology of the prepared NiPc(OH)(4)/PEO composite films under different dry conditions was characterized by scanning electron microscopy (SEM). The electrochemical behavior of NiPc(OH)(4)/PEO composite film modified GCE toward the catalytic oxidation of nitrite in pH 7.0 phosphate buffer solution (PBS) was investigated by cyclic voltammetry (CV). After drying under an infrared lamp, the fabricated sensor showed a pronounced electrocatalytic activity improvement toward the oxidation of nitrite and led to a significant decrease in the anodic overpotentials compared with bare GCE, which should be ascribed to the synergistic effect of NiPc(OH)(4) and PEO, as well as the enlarged electrochemical effective surface area after drying. Using differential pulse voltammetry (DPV), the sensor gave a linear response to nitrite over the concentration range of 0.1-5,300 mu M, with a detection limit of 0.0522 mu M. The nitrite sensor exhibits good sensitivity, selectivity, and stability and has been applied for the determination of nitrite in water samples.