Electric field induced polarization and electrochemical sensing performance of nickel-based organic–inorganic hybrid system

A single-step, wet chemical synthesis route has been applied for the fabrication of nickel(II)-aniline complex using aniline as a complexation ligand. The aniline molecules coordinate with nickel(II) through the amino group, confirmed by the spectroscopic analysis techniques. The X-ray diffraction analysis predicted the cubic structure of the complex where Ni(II)-ions are arranged diagonally across the cubic faces of the –NH₂ network. The Ni(II)-aniline complex exhibited the electric field induced hysteresis loop due to the weak dipolar type of interaction between the Ni(II) and the lone pair of nitrogen of the aniline ligand. With gradual addition of cysteine molecule to the Ni(II)-aniline complex, an increasing trend of maximum polarization and remnant polarization were noticed, which implied the space charge polarization contribution within the complex. The synthesized complex material was further applied as an electrocatalyst for the electrochemical recognition of cysteine using the cyclic voltammetric and square wave voltammetric techniques. The Ni(II)-aniline complex performed well as a selective catalyst for the electro-oxidation of cysteine with moderately good values of sensitivity and limit-of-detection, as evidenced by chronoamperometry study.