Enhanced Electrochemical Detection of Nitrobenzene in Environmental Samples Using Carbon Paste Electrode Modified with Ni@MOF-5 Nanocomposite

Ni/MOF-5 nanostructure was used as a good mediator for modifying carbon paste electrode. This nanomaterial was found as an excellent electro-catalyst for the electro-oxidation and electro-reduction of nitrobenzene (NB). The modified electrode revealed low charge transfer resistance of 2.43 k omega based on the electro-impedance spectroscopic studies. Cyclic voltammetric studies indicated a 1.62-fold increase in the geometric surface area of the modified electrode compared with that of the unmodified electrode. Effect of the modifier amount was studied. The results showed that 5% of the modifier was enough for well-function of the electrode. Double step chronoamperometric studies were also conducted. The studies confirmed an increase in both diffusion coefficient and electro-reduction rate constant of the electrode toward NB at the electrode surface. The electrode has shown an excellent performance in the range of 2.3 x 10(-8)-1 x 10(-2) M in 0.1 M Briton-Robinson buffer solution (pH 5.0). It revealed good selectivity toward a variety of coexisting organic and inorganic species, and it was successfully applied for the determination of NB in river water samples near the regional industrial cities.