Double-shelled yolk-shell Si@C microspheres based electrochemical sensor for determination of cadmium and lead ions

In this work, we report double-shelled yolk-shell Si@C structure as a high-performance electrochemical sensing material for heavy metal ions. A SiO₂-assisted polybenzoxazine (PB) coating strategy is used to synthesize highly monodispersed Si@C microspheres. After thermal carbonization of PB layers and selective removal of the SiO₂ layers, Si@C microspheres were prepared. The resultant Si@C microspheres exhibit uniform spherical morphology and clearly double-shelled yolk-shell structures. The obtained Si@C microspheres are employed to prepare the chemically modified electrode for the sensitive determination of Cd(II) and Pb(II). By the method of anodic stripping voltammetry, the Si@C-based electrode shows a very wide linear dynamic range for target ions (e.g., 0.5-400 μg L^-1 for Cd(II) and Pb(II)) and low limit of detections (e.g., 0.068 μg L^-1 for Cd(II) and for 0.105 μg L^-1 Pb(II)). The remarkable results, such as excellent resistance to interference ions, good repeatability, and reproducibility were also obtained. Furthermore, compared with those Cd(II) and Pb(II) sensors known in the literature, the analytical performance of Si@C-based electrode is better. Finally, when further used to determine Cd(II) and Pb(II) in tap water and lake water, the results of fabricated electrode successfully achieve good consistency with the data obtained from inductively coupled plasma-mass spectrometry (ICP-MS).