A specific electrochemiluminescence sensor for selective and ultra-sensitive mercury(ii) detection based on dithiothreitol functionalized copper nanocluster/carbon nitride nanocomposites

Electrochemiluminescence (ECL) sensors are useful for the detection of heavy metal pollutants, in particular mercury(ii) ions, in water samples. We demonstrate the superior sensing performance of Hg using a nanocomposite material based on carbon nitride nanosheets (CNNSs) and copper nanoclusters functionalized by dithiothreitol, which not only stabilizes the clusters, but also improves the sensitivity of Hg detection. The ECL mechanism is related to the reaction of the nanocomposite with KSO in the electrochemical system, while the presence of Hg leads to quenching of its excited state, and the suppression of the formation of anion-radicals. The Hg(ii) sensor presented here is cheap and fast, and shows high selectivity for the detection of Hg on the background of other mono-, di-, and trivalent ions, with a linear range of 0.5-10 nM and the detection limit as low as 0.01 nM.