Enhanced Electrochemical Detection of Lead Ions Using Schiff Base/MoS₂ Modified Screen-Printed Electrodes

Environmental contamination by heavy metals (HMs) remains a critical concern; among them, Pb²⁺ is distinguished by its toxicity, bioaccumulation, and persistence. Here, we present disposable, noble-metal-free screen-printed carbon electrodes (SPCEs) functionalized with MoS₂ nanosheets covalently conjugated to newly synthesized Schiff bases (SB1, SB2) via a monochloroacetic-acid linker, affording a chemically defined MoS₂-SB interface for enhanced Pb²⁺ sensing in water. Using square-wave anodic stripping voltammetry (SWASV) under optimized conditions in PBS (pH 4.0), the MoS₂@SB2/SPCE exhibits markedly higher currents than both bare and other modified electrodes. The sensor achieves an area-normalized sensitivity of 220.344 μA μM^-1 cm^-2, a limit of detection of 0.267 μM, and a primary linear range of 1-5 μM for Pb²⁺. This covalent interfacial design couples the high surface area and conductivity of MoS₂ with SB2 driven chelation, yielding good selectivity, device-to-device reproducibility, and reliable performance in tap water samples. Our results outline a viable path for the low-cost and on-site monitoring of lead ions in complex water matrices.