Dopamine detection using leaf-shaped ZnO synthesized from zinc shells of recycled batteries

Abstract

This study presents a cost-effective and sustainable method for synthesizing ZnO from electronic waste (e-waste) for the electrochemical detection of dopamine (DA) using a single metal oxide. The purity and various properties of the ZnO were confirmed using advanced techniques. The growth of ZnO clusters along the [0001] direction results in the formation of leaf-shaped ZnO with a direct band gap of 3.27 eV. Cyclic voltammetry, differential pulse voltammetry, and amperometric studies demonstrated successful DA detection at the ZnO–glassy carbon electrode in aqueous media, with an equal number of electron and proton pathways for DA oxidation. The sensor exhibited a linear response over a wide concentration range (0.01 to 100 μM), with a low limit of detection of 0.47 nM and a high sensitivity of 0.0389 A M⁻¹. Additionally, the sensor showed high selectivity, repeatability and reproducibility with relative standard deviation of 4.80% in DA detection and proved effective in real sample analysis. These results suggest that the developed sensor holds great potential as a sensitive, practical, and cost-efficient tool for DA monitoring. Furthermore, the approach contributes to sustainable management of zinc–carbon battery waste by producing valuable ZnO.