Electrochemical deposition of bismuth on activated graphene-nafion composite for anodic stripping voltammetric determination of trace heavy metals

In this study, we report the first example of a bismuth film electrode plated in situ using activated graphene (AG). The AG was prepared through of process of chemical activation of graphene oxide (GO) with KOH to create pores. The composite electrode was enhanced as an electrochemical sensing platform to determine trace Zn2+, Cd2+, and Pb2+ using differential pulse anodic stripping voltammetry. The surface morphology of the AG-NA/Bi composite film modified electrode was investigated by scanning electron microscopy and transmission electron microscopy. The electrochemical properties of the AG-NA/Bi composite electrode were evaluated to examine the effects of experimental variables, such as deposition potential, deposition time, bismuth concentration, and stirring speed during pre-concentration, on the determination of trace metals in 0.1 M acetate buffer solution (pH 4.5). Linear calibration curves ranged from 5 to 100 μg L−1 for trace heavy metal ions. The detection limits were 0.57 μg L−1 for Zn2+, 0.07 μg L−1 for Cd2+, and 0.05 μg L−1 for Pb2+ (S/N = 3). The limits of detection achieved are much lower than the guideline for drinking water quality provided by the World Health Organization (WHO). The AG-NA/Bi composite film electrodes were successfully applied to analysis trace metals in real samples.