Mechanical Instability of Gold Nanoparticles during Mercury Amalgamation

Mechanical Instability of Gold Nanoparticles during Mercury Amalgamation

Gold exhibits a strong affinity for mercury, and is, for that reason, frequently used as an electrode material for mercury detection. In light of the current trend towards ever smaller and thinner electrode surfaces, we were interested in the effects of detecting large concentrations of mercury on micro scale gold surfaces. Electrochemically saturating gold microparticles with mercury results in a 9-fold increase in volume and, in some cases, loss of electrical contact with the underlying glassy carbon spheres. Subsequent stripping of the mercury from the gold microparticles dramatically alters both the morphology and the composition of the microparticles. Understanding this mechanical instability will help to overcome one of the unique pitfalls of using micro scale gold surfaces in mercury detection.

What has motivated you to conduct this work?

We have long been interested in the creation of electrochemical sensors for heavy metal detection. My group has investigated detection of metals ranging from arsenic, particularly apposite considering the incidence of chronic arsenic poisoning from ground water in Bangladesh, to manganese to mercury. Coming at this topic from the other direction, my group has also done considerable work in nanoparticles and designer electrode surfaces. I anticipated that mercury's affinity for gold, which can be a problem in terms of long-term viability of even bulk gold electrodes, would have interesting ramifications on the micro scale.

Where do you see this work developing in the future?

The composition of an electrode surface obviously has a great impact on the processes observed. Micro- and nanoparticle decorated carbonaceous material presents a rich mine of material for future research, with potential applications in more fields than that of pure chemistry.

Are there any particular challenges facing future research in this area?

The challenges facing this particular area of research mostly stem from the relative novelty of the field. Micro- and nanoparticles are still a young technology, and, as this article demonstrates, they do not behave identically to their bulk counterparts. Assumptions about their properties, whether intrinsic or in relationship to certain applications, can result in wasted time, but I am confident that further exploration of the field will pave the way to a better understanding of micro- and nanoparticles and their uses.