Pre-enrichment-free electrochemical detection of lead ions using functionalized tungsten oxide: Integration of surface functionalization and redox cycling mechanisms

Methods for electrochemical detection of heavy metal ions have garnered widespread attention due to their high sensitivity, ease of operation, low cost, and suitability for on-site detection. However, these methods typically require a pre-enrichment step to improve the detection limit and sensitivity, which increases operational complexity and introduces potential errors. In this study, tungsten oxide electrodes with various functional groups were prepared by electrodeposition and high-temperature annealing, utilizing the amphoteric properties of l-alanine. The proposed electrodes exhibited high-performance Pb²⁺ sensing, with a sensitivity of 26.20 μA μM^-1 cm^-2, without pre-enrichment. Experimental results demonstrated that the electrode not only possesses excellent anti-interference capability and good reproducibility but also exhibits high accuracy and recovery rates in detecting actual water samples. This pioneering detection strategy harnesses tungsten's valence properties and surface functional groups' adsorption capacity to detect Pb²⁺ directly. The method is simple, rapid, and efficient, making it suitable for routine monitoring of heavy metal ions in complex environments. This innovative approach holds significant promise for a wide range of applications in environmental monitoring.