Graphene nanosheets modified with curcumin-decorated manganese dioxide for ultrasensitive potentiometric sensing of mercury(II), fluoride and cyanide

A glassy carbon electrode (GCE) was modified by electropolymerization of curcumin on MnO2-Gr nanosheets to obtain a detection method for Hg(II) and for the anions fluoride and cyanide. The complexation by curcumin can be monitored bypotentiometry. The results revealed a cathodic shift for the simultaneous detection of fluoride and cyanide and an anodic shift for the mercury(II) sensing, with peak potentials of -0.24, 0.12 and 0.82V, respectively (vs. Ag/AgCl). The modified GCE is fairly selective, reproducible and repeatable. The detection limits are 19.2nM for Hg(II), 17.2nM for fluoride, and 28.3nM for cyanide (LOD, S/N=3). The method was successfully applied to the analysis of spiked samples of tap water, river water and petrochemical refinery wastewater.