Self-assembled benzoic acid functionalized graphene oxide sheets with zinc (II) ions: Graphene oxide framework; novel material for environmental sensing application

A framework of graphene oxide (GOF) was obtained by self-assembly of benzoic acid functionalized graphene oxide (BFG) with Zn (II) ions via coordination chemistry. The crystalline morphology of the graphene oxide framework (GOF) was confirmed by X-ray diffraction analysis and transmission electron microscopy. The functionalization of graphene oxide and framework formation was confirmed using Raman and FT-IR spectroscopy while morphology of BFG and GOF was studied using scanning electron microscopy with elemental analysis. This newly synthesized GOF material is used for electrochemical oxidation of nitrophenol isomers such as 2-NP and 4-NP using cyclic voltammetry and differential pulse voltammetry on glassy carbon electrode (GOF/ GC electrode). The GOF/GC electrode showed improved electrochemical behavior for nitrophenols oxidation as compared to graphene oxide modified glassy carbon electrode (GO/GC electrode) and bare GC electrode. The GOF based sensor was found to be highly sensitive with detection limit of 60 nM, for 2-NP and 96 nM for 4-NP, and their corresponding sensitivities were 8.35 mu A mu M-1cm- 2 and 2.22 mu A mu M- 1cm- 2 respectively. The enhanced electrochemical detection of nitrophenols might have been resulted on GOF/GC electrode due to accumulation of these nitrophenols and for this the binding constant calculated using Langmuir isotherm equation are 29 x 103 M-1 (for 2-NP) and 46 x 103 M-1 (for 4-NP).