Voltammetry determination of Cd(II) and Pb(II) at TiO₂/reduced graphene oxide modified electrodes

Abstract

In this article, a TiO₂/reduced graphene oxide (rGO) composite was synthesized from rGO and soluble titanium hydroxide peroxide complexes. The obtained materials were characterized by X-ray diffraction, scanning electron microscopy, nitrogen adsorption/desorption, Raman spectroscopy and energy dispersive X-ray spectroscopy elementary mapping. The TiO₂/rGO composite was used as an electrode modifier for developing an electrochemical sensor to simultaneous analysis of Cd(II) and Pb(II) by using differential pulse anodic stripping voltammetry (DP-ASV). Under optimal conditions, the linear correlation between the stripping peak current and the metal ion concentration is good in the range of 5-100 ppb for both metals (R² ≥ 0.998), and a low detection limit (3.17 ppb for Cd(II) and 2.42 ppb for Pb(II)) was obtained. The interference study revealed that some metal cations had little influence on the DP-ASV signals of Cd(II) and Pb(II). In addition, the developed electrode exhibited satisfied reproducibility and repeatability. The TiO₂/rGO-modified electrode was tested toward the detection of Cd(II) and Pb(II) in river waters and the obtained exceptional recoveries and results were further associated with AAS results. This study indicates that the TiO₂/rGO composite might be an alternative for practical applications in the electrochemical determination of heavy metal ions in aquatic solutions.