Sensitive Electrochemical Detection of Pb²⁺ and Cd²⁺ in Water Using α-MnO₂-Based Electrode Materials

Heavy metal contamination of water represents one of the major environmental and public health challenges, especially in industrialized and urban areas. Due to their non-biodegradable nature, persistence and ability to bioaccumulate in ecosystems, toxic metal ions such as Pb²⁺ and Cd²⁺ can pose serious risks to aquatic organisms and human health even at low concentrations. Their presence in water may originate from industrial effluents, agricultural runoff, wastewater discharge and natural geochemical processes. Prolonged exposure to lead and cadmium has been associated with severe health effects, including kidney damage, neurological disorders, developmental problems and increased carcinogenic risk. Therefore, the development of simple, sensitive and environmentally friendly analytical methods for monitoring trace levels of heavy metals in water is of great importance. In this study, α-MnO₂-based electrodes were investigated electrochemical platforms for the detection of Pb²⁺ and Cd²⁺ ions in aqueous solutions. α-MnO₂ was synthesized by a hydrothermal procedure and combined with Vulcan carbon and Nafion to prepare a catalytic ink deposited onto a glassy carbon electrode. The synthesized material was characterized by X-ray diffraction and scanning electron microscopy, confirming the formation of the α-MnO₂ crystalline phase. Electrochemical measurements were performed in 20 mM H₂SO₄ + 30 mM KCl using anodic stripping voltammetry. The deposition potential and deposition time were optimized, with -1.0 V and 120 s selected as suitable experimental conditions. The α-MnO₂/Vul/GC electrode exhibited well-defined oxidation peaks for Pb²⁺ and Cd²⁺ at approximately -0.44 V and -0.74 V vs. SCE, respectively. These results indicate that α-MnO₂-based electrodes represent a promising platform for electrochemical monitoring of heavy metals in water, offering a simple, sensitive and environmentally safer alternative to conventional mercury-based electrodes.