Scientists in China have taken a step towards a new sensor for detecting hidden explosives.

Li-Jun Wan at the Chinese Academy of Sciences in Beijing and his team have used a combination of two well known electrochemical techniques to look at the behaviour of trinitrotoluene (TNT) on metal surfaces.

Using electrochemical scanning tunnelling microscopy they studied the structure of TNT at the surface of a single crystalline gold electrode. Combining this with cyclic voltammetry allowed them to investigate the electrochemical reactions of TNT at the surface of the electrode.

Understanding TNT's structure on metal surfaces is a prerequisite for sensor design

'Understanding the adsorption and layer structure of TNT on electrode surfaces is important in tracing concealed explosives and a prerequisite in sensor design,' says Wan. He explains that using electrochemical techniques to study compounds like TNT is desirable because they are both simple and highly sensitive. The group found that gold electrodes are particularly sensitive to the adsorption of TNT, which is pleasing because gold layers are easy to make.

Gary Attard, professor of electrochemical surface science at Cardiff University, UK, said the team's work is an indication of how single crystalline electrode surfaces may have future uses for chemical analysis. 'The combination of electrochemical sensitivity with chemical discrimination at the molecular level looks extremely promising as a new analytical procedure.'

Wan explains that future work will include looking at how the molecular structure affects the alignment of TNT on the surface of gold and that their end goal is to use this concept to design metal sensors for detecting nitroaromatic explosives.

Katherine Davies