Carbon Nanostructure Curvature Induced from the Rapid Release of Sulfur upon Laser Heating

Abstract

Laboratory-generated synthetic soot from benzene and benzene-thiophene was neodymium-doped yttrium aluminum garnet (Nd:YAG) laser and furnace annealed. Furnace annealing of sulfur doped synthetic soot resulted in the formation of micro-cracks due to the high pressures caused by explosive sulfur evolution at elevated temperature. The heteroatom sulfur affected the carbon nanostructure in a different way than oxygen. Sulfur is thermally stable in carbon up to~1000 • C and thus, played little role in the initial low temperature (500 • C) carbonization. As such, it imparted a relatively unobservable impact on the nanostructure, but rather, acted to cause micro-cracks upon rapid release in the form of H 2 S and CS 2 during subsequent traditional furnace heat treatment. In contrast, Nd:YAG laser heating of the sulfur doped sample acted to induce curvature in the carbon nanostructure. The observed curvature was the result of carbon annealing occurring simultaneously with sulfur evolution due to the rapid heating rate.

Pyrolysis of Porous Organic Polymers under a Chlorine Atmosphere to Produce Heteroatom-Doped Microporous Carbons

“…Experimental data show that during carbonization, most of the initial oxygen in the raw materials is lost at the beginning of pyrolysis (lower temperature region), and hence the intermediate species formed after oxygen evolution dictate the resulting carbon skeleton structure and thus its ability to graphitize [25]. Unlike oxygen, nitrogen and sulfur are thermally more stable in the carbon scaffold, and hence they affect the carbon structure in a very different way than oxygen [26,27]. They play a limited role in the initial low-temperature carbonization.…”

Non-Graphitizing Carbon: Its Structure and Formation from Organic Precursors

“…These authors showed that carbon nanostructures produced from the nitrogen-containing precursors displayed greater curvature, and they suggested that this was because the presence of nitrogen facilitated pentagon formation. Similarly, recent work by Abrahamson and Vander Wal has shown that annealing of sulphur-doped synthetic soot can result in curvature of the carbon structure, which may be due to the formation of non-hexagonal carbon rings [46].…”