Square Wave Anodic Stripping Voltammetry Applied to a Nano-Electrode for Trace Analysis of Pb(II) and Cd(II) Ions in Solution

In this work we describe the Square Wave Anodic Stripping Voltammetry (SWASV) electrochemical technique for the determination of lead (Pb
²⁺
) and cadmium (Cd
²⁺
) metal ions at concentration of sub-part per billion (ppb) in aqueous solution. Moreover, simple and low-cost procedures for the fabrication of high performance working nano-electrode are reported. The electrode structure consists of a graphene paper (GP)
$240~\mu \text{m}$
thick with the function of electrical conductor and substrate, a layer of nafion 0.5-
$0.7~\mu \text{m}$
thick onto the graphene paper and bismuth nanoparticles embedded in the nafion thin layer. The bismuth nanoparticles were fabricated by electrodeposition starting from Bi(III) ions, employing a key step of hydrogen ions of nafion
$\text{H}^{\mathbf {+}}$
exchange with bismuth ions Bi(III). This procedure is aimed to improve the bismuth nanoparticles concentration. The SWASV applied to the low-cost nanoelectrode allows detecting Pb
²⁺
and Cd
²⁺
at concentration as low as 0.1 ppb.