Studies on the electrochemical properties of nickel phtalocyanine for impedimetric detection of environment pollutants: hydroquinone and bisphenol A

A self-assembled film of nickel phtalocyanine (NiPc) has been immobilised onto gold (Au) substrate to develop a new impedimetric method for environmental pollutants detection. NiPc/Au electrode was first characterised using contact angle measurements and cyclic voltammetry to investigate the adhesion and the kinetic behaviour of the self-assembled film. Results demonstrated the interaction between Au and benzene group and at the same time showed the formation of a completely covered NiPc layer on the Au surface. In addition, the NiPc film seems to exhibit reversible redox behaviour and is found to act as an electronic conductor which allows rapid electron transfer. The electrochemical impedance spectroscopy spectra of the NiPc/Au electrode, as a function of hydroquinone (HQ) and Bisphenol A (BPA) concentration, reveal that the value of the charge transfer resistance increases with increased concentration. The electrical behaviour of the structure was studied according to an equivalent circuit by fitting the experimental spectra. Moreover, this technique demonstrates that this membrane exhibits a high sensitivity towards the toxic pollutants HQ and BPA. The differences in selectivity are clearly displayed by variations in the membrane resistance (R_m) and in the charge transfer resistance (R_tc) of the interface.