سنتز داربست‌هاي فلز-آلي اصلاح شده با نانومواد كربني براي اندازه‌گيري يون فلزات سنگين به روش الكتروشيميايي

In the present study, due to the importance of detecting chromium(III) an‎d chromium(VI) ions as toxic compounds for the environment an‎d human health, a highly sensitive electrochemical sensor for small amounts of chromium(III) an‎d chromium(VI) ions using a metal-organic framework, copper(II) benzene 1,4-dicarboxylic acid (CuBDC)/graphene oxide (GO) composite is reported. The metal-organic framework CuBDC was synthesized by hydrothermal method an‎d analyzed an‎d investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Thermogravimetric analysis (TGA), an‎d Field emission scanning electron microscopy (FE-SEM). an‎d graphene oxide was synthesized by modified Hammer method an‎d analyzed an‎d investigated by X-ray diffraction (XRD), infrared spectroscopy (FT-IR) an‎d atomic force microscopy (AFM) images. The formed CuBDC/GO composite was characterized by X-ray diffraction (XRD), infrared spectroscopy (FT-IR) an‎d field emission scanning electron microscopy (FE-SEM). Then, the composite was dro‎p-cast onto the electrode surface. Various parameters, including the selec‎tion of the appropriate ratio of the composite components, the contact time of the composite with the aqueous solution containing the target species, the effect of pH, the stability of the CuBDC/GO film an‎d the effect of the scanning speed, were investigated an‎d optimized. Next, the Glassy carbon (GC) electrode was modified with a thin film of CuBDC/GO an‎d the electrochemical behavior of the film was investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV) an‎d electrochemical impedance spectroscopy (EIS). The results showed that the GC/CuBDC/GO electrode has the ability to detect an‎d measure very low amounts of chromium(III) an‎d chromium(VI) ions in aqueous solutions. Using differential pulse voltammetry, the sensitivity an‎d detection limit were calculated as 0.0313µA/pM an‎d 17.04fM for chromium(III) ion an‎d the sensitivity an‎d detection limit were calculated as 0.005µA/pM an‎d 10.4fM for chromium(VI) ion. The linear response range for chromium(III) an‎d chromium(VI) ions was calculated from femtomolar up to 5pM. The results showed that the fabricated sensor has better figures of merit compared to other existing sensors for chromium(III) an‎d chromium(VI) ions.

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