Preparation of a novel Ni-MOF and porous graphene aerogel composite and application for simultaneouselectrochemical determinationof nitrochlorobenzene isomers with partial least squares.

Abstract

Metal-organic framework Ni2(BDC)2(DABCO) (Ni-MOF)/porous graphene aerogel (PGA) composites were fabricated for the first time. The introduction of PGA enhances conductivity of Ni-MOF, prevents Ni-MOF from accumulating, reduces the size of Ni-MOF, and increases the pore size of composites, which improve the electrocatalytic activity of Ni-MOF@PGA-2. The prepared sensors based on Ni-MOF@PGA-2 composite show the highest catalytic current towards electroreduction of 2-nitrochlorobenzene (2-NCB), 3-nitrochlorobenzene (3-NCB), and 4-nitrochlorobenzene (4-NCB) at around - 0.61V, - 0.56V, and - 0.57V (vs. Ag/AgCl) with respect to other sensors. The reaction mechanisms also are discussed. Under optimized experiment conditions, the Ni-MOF@PGA-2/GCE displays the widest linear range (6-1260, 4-980, and 2-1280μM for 2-NCB, 3-NCB, and 4-NCB, respectively) for determinationof individual nitrochlorobenzene isomers (NCBIs) compared to that of recent reports, and relatively low detection limit (0.093, 0.085, and 0.051μM for 2-NCB, 3-NCB, and 4-NCB, respectively). More importantly, three NCBIs in the mixture were for the first timesimultaneously determined by combining differential pulse voltammetry (DPV) based on Ni-MOF@PGA-2/GCE with partial least squares (PLS) chemometrics modeling method. The proposed method was evaluated towards the determination of NCBI mixtures in tap water and Jing lake water, and satisfactory recoveries were obtained. Graphical abstract.