Bismuth Nanoclusters/Porous Carbon Composite: A Facile Ratiometric Electrochemical Sensing Platform for Pb2+ Detection with High Sensitivity and Selectivity

In this work, a ratiometric electrochemical sensor was constructed for the detection of Pb2+ based on a bismuth nanocluster-anchored porous activated biochar (BiNCs@AB) composite. BiNCs with loose structure and AB with abundant oxygen-containing functional groups are favorable for Pb2+ adsorption and preconcentration; meanwhile, porous AB provides more mass transfer pathways and increases electronic and ion diffusion coefficients, realizing high sensitivity for Pb2+ detection. At the same time, BiNCs were proposed as an inner reference for ratiometric electrochemical detection, which could greatly enhance the determination accuracy. Under optimized experimental conditions, the anodic peak current ratio between Pb2+ and BiNCs exhibited a good linear relationship with the concentration from 3.0 ng/L to 1.0 mg/L. The detection limit can be detected down to 1.0 ng/L. Furthermore, the proposed sensor demonstrated good reproducibility, stability, and interference resistance, as well as satisfactory recoveries for the detection of Pb2+ in real samples.