Sensitive and selective electrochemical detection of Cd2+ by using bimetal oxide decorated Graphene oxide (Bi2O3/Fe2O3@GO) electrode

Bimetal oxide decorated graphene oxide (Bi2O3/Fe2O3@GO) was synthesized by a simple hydrothermal method and used as an electrochemical sensor for sensing the toxic cadmium (Cd2+) ion. For comparative analysis graphene oxide (GO), Iron oxide nanoparticle decorated on GO sheets (Fe2O3@GO) and bismuth oxide nanoparticle decorated on GO sheets (Bi2O3@GO) were synthesized. Structurally and morphologically two different nanoparticles of Bi2O3 and Fe2O3 on GO sheets were confirmed from XRD, FESEM techniques respectively. Latter the inter planner spacing of the nanoparticles and GO sheets were calculated from the HRTEM techniques, which matched with the exact value obtained through XRD analysis. Functional groups like hydroxyl, epoxide, carbonyl, and carboxyl were investigated through FT-IR techniques. Detection of Cd2+ was performed through square wave voltammetry (SWV) technique with an optimized pH (5.0), deposition potential ( - 1.0 V) and deposition time (90 s). The Bi2O3/Fe2O3@GO modified electrode shows the better electro-catalytic property with more no. of active sites which facilitate the electron transfer between the electrode and species. The nanocomposite Bi2O3/Fe2O3@GO was found to be more sensitive than blank, GO, Fe2O3@GO and Bi2O3@GO modified electrodes. The Bi2O3/Fe2O3@GO modified electrode exhibits a linear range of 6.2 ng L-1 to 1160.2 ng L-1 and limit of detection of 1.85 ng L-1 towards the detection of Cd2+. A very high sensitivity of 2034.2 A cm(-2) g(-1) L was recorded for the Bi2O3/Fe2O3@GO electrode. The interference study explains the Bi2O3/Fe2O3@GO electrode is selective towards Cd2+ among various biomolecules and heavy metal ions. Real sample analysis study confirms the ability of the Bi2O3/Fe2O3@GO electrode for detecting Cd2+ present in water, fruits, soil, and biological samples. The Bi2O3/Fe2O3@GO electrode has good stability up to 40 days exhibiting without any current loss.