Hg²⁺ Ions Sensor: Single Walled Carbon Nanotubes Incorporated Zn-Metal Organic Framework

In the present work, zinc benzene 1,4 dicarboxylate (ZnBDC) metal organic framework (MOF) and its composite with single-walled carbon nanotubes (SWNTs), we called as SWNTs@ZnBDC, has been synthesized by traditional solvothermal method. The synthesized materials have been evaluated with various techniques such as Fourier transform infrared spectroscopy, X-ray diffraction (XRD), thermogravimetric-differential thermal analysis, Brunauer–Emmett–Teller surface area analysis, cyclic voltammetry, and electrochemical impedance spectroscopy. The sensor has been fabricated by depositing SWNTs@ZnBDC MOF on a glassy carbon electrode (GCE). The SWNTs@ZnBDC/GCE electrode shows excellent sensing behaviour in terms of selectivity towards Hg²⁺ ions only at pH = 5 and does not show any sensing response towards Pb²⁺, Cr²⁺, Cd²⁺, Cu²⁺, and Ni²⁺ ions at a concentration of 1 μM. For the Hg²⁺ ions, the sensor shows a high sensitivity of 0.86 μA/nM with a limit of detection of 6.74 nM and a limit of quantification of 5 nM.