Post-transition metal electrodes for sensing heavy metal ions by stripping voltammetry

Heavy metal ions contamination is an ever-growing threat to human health and ecosystems. Analytic sensing of heavy metal ions is a prerequisite step toward addressing this challenge. Electroanalytical technique is an effective and convenient way to detect heavy metal ions. Especially, stripping voltammetry techniques have been utilized for sensing metal ions at trace levels in different sample matrices. The choice of the working electrode materials plays a decisive role in the precision and sensitivity of stripping voltammetry. Post-transition metals (including elements in group 12) are elements with low melting points, demonstrating unique properties including amalgamation with heavy metal ions that enhance the performance of stripping voltammetry during the pre-concentration step, which make them particularly suitable for heavy metal ion sensing. Here, for better understanding the features and advantages of post-transition metals in stripping voltammetry, eight classes of working electrodes based on zinc (Zn), mercury (Hg), gallium (Ga), indium (In), tin (Sn), lead (Pb), antimony (Sb), and bismuth (Bi), are reviewed, with their efficiency and effectiveness compared and recent progresses discussed. Additionally, liquid metal electrodes based on post-transition metals and alloys are also presented. This review provides viable directions for future development of heavy metal ion sensors based on post-transition metals.