Disposable and Low-Cost Electrode Based on Graphene Paper-Nafion-Bi Nanostructures for Ultra-Trace Determination of Pb(II) and Cd(II)

• Main Authors: Antonino Scandurra, Francesco Ruffino, Mario Urso, Maria Grazia Grimaldi, Salvo Mirabella
• Format: Article
• Language: English
• Published: MDPI AG 2020-08-01
• Series: Nanomaterials
• Subjects: graphene paper; perfluorosulfonic ionomer; bismuth; SWASV; trace analysis
• Online Access: https://www.mdpi.com/2079-4991/10/8/1620
• ISSN: 2079-4991

There is a huge demand for rapid, reliable and low-cost methods for the analysis of heavy metals in drinking water, particularly in the range of sub-part per billion (ppb). In the present work, we describe the preparation, characterization and analytical performance of the disposable sensor to be employed in Square Wave Anodic Stripping Voltammetry (SWASV) for ultra-trace simultaneous determination of cadmium and lead. The electrode consists of graphene paper-perfluorosulfonic ionomer-bismuth nano-composite material. The electrode preparation implies a key step aimed to enhance the Bi³⁺ adsorption into nafion film, prior to the bismuth electro-deposition. Finely dispersed bismuth nanoparticles embedded in the ionomer film are obtained. The electrode was characterized by Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), Atomic Force Microscopy (AFM), X-ray Photoelectron Spectroscopy (XPS) and Electrochemical Impedance Spectroscopy (EIS). The electrode shows a linear response in the 5–100 ppb range, a time-stability tested up to almost three months, and detection limits up to 0.1 ppb for both Pb²⁺ and Cd²⁺. The electrode preparation method is simple and low in cost and the obtained analytical performance is very competitive with the state of art for the SWASV determination of Pb²⁺ and Cd²⁺ in solution.