Alkalized Ti3C2 MXene enabling in-situ growth of Bi nanobelts to develop electrochemical sensor for simultaneous detection of dual heavy metal ions

Accelerated industrialization has heightened heavy metal contamination in marine ecosystems, with filter-feeding bivalves like scallops accumulating these toxins, posing significant food safety risks. Conventional detection methods face limitations in cost and portability. In this work, we developed a novel in-situ growth strategy by utilizing alkalized Ti 3 C 2 MXene (alk-MXene) to enable the uniform formation of Bi nanobelts directly on its surface, a significant improvement over pristine Ti 3 C 2 MXene, attributed to the higher density of negatively charged hydroxyl groups on alk-MXene. On this basis, the in situ-grown Bi nanobelts on alk-MXene modified pencil graphite electrode (Bi@alk-MXene/PGE) was used for the electrochemical detection of Cd 2+ and Pb 2+ in a single run. Compared to the alk-MXene/PGE, the Bi@alk-MXene/PGE exhibited 1.4-fold and 1.2-fold higher peak current intensities for Cd 2+ and Pb 2+ , respectively, demonstrating its enhanced sensitivity for detection. Linear relationships were observed for Cd 2+ in the range of 1.0 × 10 −5 –5.5 × 10 −1  mg/L and Pb 2+ in 5.0 × 10 −4 –5.5 × 10 −1  mg/L, with detection limits of 1.72 × 10 −7  mg/L and 1.04 × 10 −6  mg/L based on S/N = 3, respectively. This sensor was successfully applied to scallop samples, validating its practicality for real-sample analysis. This work uniquely combined portability, affordability and ultra-sensitivity, offering an ideal solution to meet the growing demand for reliable heavy metal monitoring in food safety monitoring field.