Applied Chemical Engineering

Hg²⁺ pollution poses a major threat to human health and the ecological environment, but there is still a lack of direct and sensitive Hg²⁺ detection technology. In this study, Cu/CuO/ZnO wires were prepared by alkaline oxidation and hydrothermal methods. Polypyrrole (PPy) was covered on the surface of the material by electrochemical polymerization. Using the principle of electrochemical signal response driven by p-n junction barrier, the material was used for the direct electrochemical detection of Hg²⁺ and was tested by differential pulse voltammetry. The composite has a good linear relationship in the Hg²⁺ concentration range of 200–1600 nmol/L, and has ultra-high sensitivity (1,010.82 μA∙L/(nmol∙cm²)) and ultra-low detection limit (2.1 pmol/L). The new sensing mode based on the interface barrier eliminates the interference of other ions. The recovery rate of Hg²⁺ in tap water, river water and sea water is 97.3%–105.0%, and the RSD is 1.8%–5.6%. This method using p-n junction barrier can be extended to the development and research of other sensors for detecting heavy metal ions.

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