2D bismuthene/graphene modified electrodes for the ultra-sensitive stripping voltammetric determination of lead and cadmium

Bismuth-based electrodes have been proved the most reliable replacement of highly toxic mercury for the anodic stripping (AS) and cathodic voltammetric determination of metal ions and organic compounds, respectively. Herein, we report for the first time on the implementation of two-dimensional (2D) bismuth, called “bismuthene”, for the AS voltammetric determination of Pb(II) and Cd(II) ions. Bulk bismuth was exfoliated by a facile and fast shear-force liquid phase exfoliation method. Exfoliated bismuthene layers were characterized by means of SEM, EDX, Raman, FT-IR, electrochemical impedance spectroscopy and cyclic voltammetry. Bismuthene colloids were mixed with dispersions of few-layer graphene, which was used as supporting material in order to achieve the desired adherence of bismuthene films onto the surface of glassy carbon electrode (GCE) as well as an effective electrical communication between them and with the electrode surface. The optimum loading of bismuthene in the bismuthene/graphene composite (2D-Bi/Gra) was investigated, while other parameters such as the deposition time and deposition potential were also examined. Under selected conditions and for a 3 min preconcentration time, the limit of detection (S/N 3) of each target ion was 0.3 μg L−1. 2D-Bi/Gra/GCEs were successfully applied to the determination of Pb and Cd in tap water samples in the presence of potassium hexacyanoferrate(II) for the alleviation of copper interference. Results suggest that 2D bismuthene/graphene modified electrodes offer great promise for the determination of sub-microgram per liter Pb and Cd and could contribute greatly in heavy metal ions and other organic compounds sensing applications.