Size controlled synthesis of Ni-MOF using polyvinylpyrrolidone: New electrode material for the trace level determination of nitrobenzene

This article reports the synthesis of nickel organic framework capped with polyvinylpyrrolidone (Ni-MOF-PVP) and their modification on glassy carbon (GC) electrode for highly sensitive and selective determination of nitrobenzene (NB) by voltammetry. The Ni-MOF-PVP was synthesized by simple in-situ solvothermal method. The transmission electron microscopy (TEM) images show that the as prepared Ni-MOF was spherical in shape with an average particle size of 322 nm. The particle size was decreased from 322 to 80 nm after the addition of 600 mg PVP to Ni-MOF. Then, the synthesized Ni-MOF-PVP was fabricated on GC electrode by drop casting. It shows two pairs of redox waves at 0.24 and 0.48 V, corresponding to Ni-II/Ni-III and Ni-III MOF-1/Ni-III MOF-2 in acetate buffer solution at pH 4. Further, the Ni-MOF-PVP modified electrode was used for the selective and sensitive determination of NB. It shows a sharp reduction peak for NB with 70 mV less positive potential and 2-fold higher reduction current when compared to bare GC electrode. The amperometric current response of NB increases while increasing its concentration from 0.2 mu M to 1 mM with a correlation coefficient of 0.9924 and the limit of detection (LOD) was found to be 97 nM (S/N = 3). Finally, the practical application of the Ni-MOF-PVP modified electrode was demonstrated by determining NB in tap and lake water samples and these results were validated with gas chromatography-mass spectrometry (GC-MS) method.