Gold Digestion

The Project

During my undergraduate degree, my grad student supervisor Matthew Griffiths developed the first gold ALD process. We made the gold precursors ourselves, but buying the starting reagent (gold chloride) was really expensive. Instead of buying the commercial reagent, we came up with a cheaper way - we bought pure gold and dissolved it ourselves using chlorine gas.

How We Did It

We purchased pure gold, which is much cheaper per gram than the starting reagent - costs by about 70% less. The gold came as small pieces that we could handle easily. We built a reaction setup where we could stir the gold and bubble chlorine gas through it.

The reaction took place via adding dropwise hydrochloric acid to potassium permanganate to generate Chlorine gas. The gas was then bubbled into a flask of gold pellets in water at room temperature. The excess unreacted chlorine gas was bubbled through a solution of sodium thiosulfate and water to consume any remaining gas. The reaction took a few hours, but we ended up with solution of gold chloride that we could use for the rest of the synthesis.

Once we had the gold chloride, we continued the synthesis as described here.

Safety

Working with chlorine gas requires careful safety measures. We did all the reactions in a fume hood with proper ventilation and gas monitoring. Everyone wore protective equipment and we had emergency procedures in place. Gold compounds can also be hazardous, so we handled them with care and disposed of waste properly.

This was part of my undergraduate research in chemistry, where we learned to be creative with lab resources.