Electrochemical sensor for mercuric chloride based on graphene-MnO₂ composite as recognition element

In this paper, graphene and MnO₂ nanoparticle were programmed to synthesize a nanocomposite, which was used to modified glassy carbon electrode (GCE). The presence of Gr-MnO₂ nanocomposite has enhanced the electrochemical performance of the GCE towards the mercuric chloride (HgCl₂). Electrochemical behaviors of HgCl₂ on different electrodes were evaluated by cyclic voltammetry, the result shows that the Gr-MnO₂ nanocomposite modified electrode showed higher chemical activity with HgCl₂ than bare GCE, MnO₂/GCE and Gr/GCE. In PBS solution (pH = 5.5), the oxidation peak current raised as the concentration of HgCl₂ increased from 12.1 to 210.8 μM, the detection limit was 2.0 μM (S/N = 3). The modified electrode showed good selectivity, high stability and excellent regeneration.