Ultrasensitive and Selective Detection of Cd(II) Using ZnSe‐Xanthan Gum Complex/CNT Modified Electrodes

Abstract

This work describes for the first time the employment of water soluble GSH‐ZnSe QDs stabilized by XG and MWCNT for electrode modification in the detection of Cd ions in a highly sensitive and selective manner resulting from the unique structure and surface chemistry of the used QDs. The surface of a glassy carbon (GC) electrode was modified through casting a thin layer of multiwalled carbon nanotubes (MWCNT) followed by a complex layer of ZnSe quantum dots (QDs) stabilized by xanthan gum (XG). Due to the electrocatalytic properties of MWCNT and electroanalytical performance of ZnSe‐XG complex, the new modified electrode significantly improves the sensitivity and selectivity of Cd(II) detection and exhibits enhanced performance in comparison to bare GC, ZnSe/GC and ZnSe/MWCNT/GC electrodes. Strong interactions between ZnSe QDs and XG resulting from hydrogen bonding and complexing association led to stabilization of ZnSe QDs and higher affinity towards Cd(II) ions adsorption compared to a ZnSe QDs film alone. The modified electrode showed linear response in a wide concentration range from 100 nM to 5 μM (R2=0.9967) along with a high sensitivity of 156.6 nA ⋅ mol−1 ⋅ L−1 and a low detection limit of 20 nM. The electrode shows high selectivity to Cd with negligible interference from other metal ions and salts.

Facile synthesis of self-assembled carbon nanotubes/dye composite films for sensitive electrochemical determination of Cd(II) ions

“…Sensors based on carbon materials, especially multi-walled carbon nanotubes (CNTs), have attracted considerable attention. For example, Ding et al used ZnSe-Xanthan Gum Complex/CNT (ZnSe-XG/CNT) to detect Cd ions in a highly sensitive and selective manner, which was attributed to the electroanalytical performance of CNT and ZnSe-XG complex [21]. And Jiang et al designed a 1,3,6,8pyrenetetrasulfonic acid sodium salt-functionalized CNTs nanocomposites (PyTS-CNTs), which showed increased selectivity and sensitivity to Cd 2+ and Pb 2+ ions due to the insertion of sulfonic acid groups [22].…”