Synthesis of a three-dimensional (BiO)2CO3@single-walled carbon nanotube nanocomposite and its application for ultrasensitive detection of trace Pb(II) and Cd(II) by incorporating Nafion

In this study, a three-dimensional (BiO)(2)CO3@ single-walled carbon nanotube (SWCNT) nanocomposite incorporating Nafion as a dispersant and sensing interface was designed and used to modify the glassy carbon electrode (GCE) for the sensitive analysis of Pb(II) and Cd(II) based on square wave anodic stripping voltammetry (SWASV). The limit of detection was 0.05 mu g/L for Pb(II) and 0.03 mu g/L for Cd(II) (S/N = 3), a linear range extended from 0 mu g/L to 60 mu g/L, and there was good repeatability. The prepared sensing interface, i.e., (BiO)(2)CO3@SWCNT-Nafion, was characterized by cyclic voltammetry (CV), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), X-ray diffraction (XRD) and SWASV. The SWCNTs in the composite film provide a three-dimensional framework for the attachment of Nafion and (BiO)(2)CO3, which efficiently promoted electron transfer and significantly enlarged the specific surface area. Moreover, the (BiO)(2)CO3 is pivotal in improving the detection sensitivity and can form multicomponent alloys with Pb(II) and Cd(II). The electrode stability is increased by the Nafion, which has very good adhesion and cation-exchange capacity and improved the sensitivity by preconcentrating more metal ions. Finally, analysis of several soil samples verified the practicability of the electrode, and some satisfactory results were obtained.