Electrochemical method is recognized as a promising technique for determination of ultratrace heavy metal ions. In order to realize a more sensitive electroanalysis, a variety of nanomaterials have been modified on the surface of working electrode.

Ultrathin materials with atomic thickness and extremely huge percentage of specific facet can exhibit some new properties and strikingly enhance electrochemical activities of their corresponding bulk counterparts. According to this, the application of ultrathin materials on the electrochemical sensing of heavy metal ions deserves exploration.

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 improving the electrochemical response of As(III) on ultrathin nanomaterials. The study results were published in Electrochimica Acta with title Gold electrode modified with ultrathin SnO2nanosheets with high reactive exposed surface for electrochemical sensing of As(III). 

In their study, ultrathin SnO₂nanosheets with high reactive exposed surface modified electrode for electrochemical sensing of As(III) was proposed. And ultrathin SnO₂nanosheets were synthesized via a simple hydrothermal process successfully with the thickness of about 0.52 nm. This oxide was used as electrode modifier, and the modified electrode exhibited good performance in stripping determination of As(III). The LOD actually measured was 5 μg L^-1 which was below the guideline value given by the World Health Organization (WHO). Compared with SnO₂ bulks, ultrathin SnO₂nanosheets showed stronger adsorption capability and better detection performance toward As(III) probably due to the atomic thickness and extremely huge percentage of (110) facet ultrathin nanosheets materials exposed. Finally, this system isapplied to the analysis of a real sample collected from Inner Mongolia, China.

Most importantly, the study provides a potential application of ultrathin materials to improving the electrochemical performance of bare gold electrode in mild acid condition.

This work is supported by the National Key Scientific Program-Nanoscience and Nanotechnology, the National High Technology Research and Development Program of China (863 Program), and the National Natural Science Foundation of China.

AFM image of ultrathin SnO₂nanosheets and height profile; Comparison of sensitivity for electrochemical detection of As(III) at bare, SnO₂ bulks and ultrathin SnO₂nanosheets modified electrode. (Imaged by JIANG Tianjia)