Two-dimensional bismuthene doped biochar for the detection of the heavy metal ion Cd(II).

Heavy metal contamination poses a significant threat to both human health and aquatic ecosystems, highlighting the urgent need for its effective monitoring. Bismuthene is a two-dimensional nanostructured material derived from the environmentally friendly and non-toxic element bismuth, offering significant potential for sustainable electrocatalytic applications. In this study, a facile synthesis method for bismuthene nanosheets and their integration with biomass-derived carbon to form BieneNS@C composites is presented. The successful synthesis of BieneNS@C was confirmed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The presence of the layered hexagonal structure of BieneNS was confirmed by transmission electron microscopy (TEM) and atomic force microscopy (AFM). The excellent electrical conductivity and enhanced current response toward Cd(II) were evaluated using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and differential pulse voltammetry (DPV). Moreover, the interaction mechanism between Cd(II) and BieneNS@C was elucidated by Fourier transform infrared (FTIR) spectroscopy. The composites were employed to modify glassy carbon electrodes (GCE) for sensitive detection of Cd(II) in aqueous solutions. The optimized sensor demonstrated excellent analytical performance, showing a linear response from 0 to 150 μg L with a detection limit of 0.2 μg L. The BieneNS@C/GCE exhibited outstanding selectivity, stability, and reproducibility. Practical application in tap water analysis achieved recovery rates of 104.8 %-105.3 %, validating the reliability of the method. These results demonstrate that the BieneNS@C-based electrochemical sensor provides a simple, low-cost, and highly sensitive platform for Cd(II) detection, with potential for real-sample analysis.