Low dimensional Bi2Te3-graphene oxide hybrid film-modified electrodes for ultra-sensitive stripping voltammetric detection of Pb(II) and Cd(II)

- Exfoliated Bi2Te3: New applications of “graphene-like” inorganic analogues in electroanalysis.
- Surfactant-free and scalable sonication-assisted liquid exfoliation of Bi2Te3 in solvents.
- Very stable dispersions of Bi2Te3 and 2D-Bi2Te3/GO composites, which can be easily cast into films.
- 2D-GO/Bi2Te3 films endow attractive sensing capabilities not attained by the bulk counterparts.
- Simultaneous screening of Pb and Cd ions at the sub-ppb concentration level.

Inorganic layered materials, also known as “graphene-like” inorganic analogues, have emerged as a new and versatile source of nanomaterials. Due to their thickness-dependent physical properties they have drawn an enormous scientific interest as regards their exfoliation and the potential use of the exfoliated two-dimensional crystals to attractive new applications in various industrial and technological sectors. This work reports for the first time, the use of low dimensional Bi2Te3-graphene oxide (GO) hybrid films as electrode's modifiers for the ultra-sensitive determination of Pb(II) and Cd(II) ions in the sub microgram-per-liter level by using anodic stripping voltammetry. Bulk Bi2Te3 was exfoliated by applying an easy-to-perform, sonication-assisted liquid exfoliation method in a triple blend of 1 + 3 + 4 v/v 1-cyclohexyl-2-pyrrolidone, acetone and water. The resulting dispersion showed a slow sedimentation rate and exhibited an extended electrode surface coverage with respect to the bulk material, as it was documented by electrochemical impedance spectroscopy comparative measurements. To achieve the desired adherence of exfoliated Bi2Te3 films at electrode surface, Be2Te3 dispersion was mixed with an aqueous dispersion of GO, which was used as supporting material. Compared with the bulk Bi2Te3/GO hybrid film-modified glassy carbon electrodes (GCEs), exfoliated Bi2Te3/GO hybrid film-modified GCEs exhibited remarkably enhanced detection capabilities and limits of detection (S/N 3) as low as 0.1 μg L−1 Pb and 0.2 μg L−1 Cd. This work provides new data on the facile preparation of stable dispersions of Bi2Te3 and Bi2Te3/GO composites, which can be easily cast into films offering highly sensitive sensors. In addition, it offers new insights in the applicability of exfoliated Bi2Te3 in electroanalysis and can trigger the development of advanced sensors based on other inorganic layered materials.

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