Electrochemical analytical tools are widely applied to Cd(II) detection and abundant achievements have been made. However, the mutual interference among the different heavy metal ions is very serious due to the intermetallic compounds formed among them and the competition for the active sites at the modified electrode surface. Thus, it is problematic to accurately detect real water samples contaminated with Cd(II) in the presence of other common coexistence of heavy metal ions, such as Zn(II), Pb(II), Cu(II) and Hg(II). Furthermore, the problem of modification nanostructured materials for the determination of Cd(II) with the drawback of costly and complex synthesis processes still remain unsolved. To realize the selective and sensitive detection with relatively simple and low cost nanostructured materials is an electrochemical analytical challenge for Cd(II) determination.

Recently, a study team led by Prof. HUANG Xingjiu and Prof. LIU Jinhuai in Institute of Intelligent Machines (IIM), Hefei Institutes of Physical Science, explored the sensitivity and selectivity sensing cadmium(II) using amino-functionalized porous SnO₂ nanowire bundles-room temperature ionic liquid nanocomposite. The paper has been accepted for publication by Sensors and Actuators B: Chemical.（http://www.sciencedirect.com/science/journal/09254005）

In this work, researchers attempted to detect ultra-trace Cd(III) with a new nanocomposite of amination functionalized porous SnO₂ nanowire bundles-room temperature ionic liquid (NH₂/SnO₂-RTIL). The NH₂/SnO₂-RTIL nanocomposite uses its efficient Cd(II) capture, and through the delicate control of experimental conditions (deposition potential and electrolyte pH), sensitive and selective detection of Cd(II) was achieved in the presence of other common coexisting ions. Notably, the possible mechanism of enhanced stripping signal was preliminarily explored and clarified. Meanwhile, the analytical application of the proposed method toward the detection of Cd(II) in a real water sample collected from Wangxiaoying sewage treatment plant, Hefei City, China, has been successfully verified. Therefore, the proposed method has the practical application potential for the effective assessment of the efficiency of wastewater treatment.

Findings of this work indicate that electrode materials and the experiment conditions, such as electrolyte pH, deposition potential, play equally crucial roles in the sensitive and selective detection of analytes.

Researchers believe that these studies are beneficial to broaden horizons of the sensitivity and selectivity of electroanalysis toward other hazardous substance. This work was supported by the National Natural Science Foundation of China (U1532123,21277146, 61573334, 21377131, 21475133 and 61474122).

Figure 1. Morphologic structure and sensitivity and selectivity studies. a) SEM image of the NH₂/SnO₂-RTIL. b) Typical SWASV signals of bare GCE,SnO₂/GCE, SnO₂-RTIL/GCE, NH₂/SnO₂/GCE, and NH₂/SnO₂-RTIL/GCE toward 0.1 µM five blended heavy metal ions.