Pharaoh's Serpents: New Insights into a Classic Carbon Nitride Material.

The combustion of mercury(II) thiocyanate to form 'Pharaoh's serpents' is a spectacular reaction first described nearly two centuries ago. The large volume of distinctive yellow branches that grow from a tiny quantity of flaming reactants makes this an enchanting demonstration, often used to depict the magic of chemistry. In recent years several videos of this bizarre process have 'gone viral' online. Formally, the reaction should yield a carbon nitride with the ideal formula C3N4 along with HgS. However, since early characterization attempts there has been little further study of the materials produced. Herein we apply modern characterization techniques to reinvestigate the nature of the carbon nitride and its intimate relationship to the HgS produced. The HgS phase forms nanoparticles that decorate the surfaces of a C3N4 foam matrix. Both of these compounds are important wide-gap semiconductors and we propose that the 'Pharaoh's serpents reaction' could be used to produce a potentially important heterojunction nanocomposite materials that could be useful optoelectronic and photocatalytic applications. [ABSTRACT FROM AUTHOR]