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). Double-shelled yolk-shell Si@C microspheres were successfully prepared and its morphology and structure were confirmed by SEM, TEM and STEM. When the obtained material was used to modified electrode, it shows good electrochemical analysis performance towards Cd(II) and Pb(II). This sensor can accurately detect Cd(II) and Pb(II) in water samples from the environment. Compared with other sensors, this sensor is more superior. [Display omitted] •Double yolk-shelled Si@C microspheres were prepared through a SiO2-assisted polybenzoxazine coating strategy.•The double yolk-shelled structure can be clearly distinguished from SEM, TEM and STEM images.•Simultaneous determination of Cd(II) and Pb(II) was achieved on Si@C modified electrode.•Compared with the other sensors, our Si@C/GCE shows a wider linear range and lower detection limits..•Si@C/GCE successfully detects Cd(II) and Pb(II) in nature samples with good recovery and accuracy.