Electrochemical method is recognized as a promising technique for determination of ultratrace heavy metal ions. To realize a more sensitive and selective electroanalysis, functional groups have been introduced into the nanomaterials. Functional Si-based nanomaterials with meso-porous structures have been used to absorb heavy metal ions. And the materials can be expectedly applied as an alternative modifier to detect heavy metal ions.

A study team led by Prof. HUANG Xingjiu and Prof. LIU Jinhuai in Institute of Intelligent Machines (IIM), Hefei Institutes of Physical Science, achieves an important progress on selective and simultaneous electrochemical detection of Cd(II) and Pb(II) ions on functionalized porous Si nanowires. Their study results were published in Electrochimica Acta with title Functionalized porous Si nanowires for selective and simultaneous electrochemical detection of Cd(II) and Pb(II) ions.

In their study, thiol (-SH) and amino (NH₂)-functionalized porous Si nanowires (Si NWs) have been demonstrated to selectively detect Cd(II) and Pb(II) with high sensitivity using square wave anodic stripping voltammetry (SWASV) analysis.

The results indicate that Cd(II) and Pb(II) can be detected with high sensitivity owing to the strong complexing capacity of thiol and amino groups. Additionally, porous Si nanowires decorated with thiol groups present different stripping behaviors from those with amino groups toward the investigated heavy metal ions, which realize the selective and simultaneous detection of Cd(II) and Pb(II). Furthermore, simultaneous detection of Cd(II) and Pb(II) has also been demonstrated without any interference.

Most importantly, the study can be further extended to selectively detect other heavy metal ions through modifying porous Si nanowires with specific organic groups.

This work is supported by the National Key Scientific Program-Nanoscience and Nanotechnology and the National Natural Science Foundation of China.

Synthesis of functional Si materials and the electro-analysis performance towards heavy metal ions. a) Schematic process of Si NWs-SH and Si NWs-NH2. b) Simultaneous detection of Pb(II) and Cd(II) on Si NWs-SH modified electrode. c) Selectivity studies of Si NWs-SH and Si NWs-NH2 modified electrode. (Image by GUO Zheng)