Discovery of carbon nanotubes in sixth century BC potteries from Keeladi, India

Abstract

Unique black coatings were observed in the inner wall of pottery shreds excavated from Keeladi, Tamilnadu, India. Raman spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy were used to understand the nature of the coating. The analysis revealed the presence of single, multi-walled carbon nanotubes and layered sheets in the coating. The average diameter of single-walled carbon nanotube found to be about 0.6 ± 0.05 nm. This is the lowest among the single-walled carbon nanotubes reported from artefacts so far and close to the theoretically predicted value (0.4 nm). These nanomaterials were coated in the pottery’s that date backs to sixth century BC, and still retain its stability and adhesion. The findings of nano materials in the pre-historic artifacts, its significance and impact are discussed in this article.

Effects of Catalyst Pretreatment on Carbon Nanotube Synthesis from Methane Using Thin Stainless-Steel Foil as Catalyst by Chemical Vapor Deposition Method

“…In order to identify the number of walls of the synthesized CNTs, HR-TEM was used. The TEM images shown in Figure 12 reveal that the CNTs formed at 850 • C possessed various types, including single-walled (bundles of single-walled CNTs, which is similar to the finding in [35]), double-walled, and multiwalled carbon nanotubes (six walls). This observation is consistent with our Raman results.…”

Iron-catalyzed graphitization for the synthesis of nanostructured graphitic carbons

“…For example, pottery from an ancient settlement called Keeladi in India has a durable black coating that was found to be made up of multi-walled carbon nanotubes. 77 These are believed to have been formed during firing from carbonization of plant matter alongside naturally occurring catalytic iron species. In another example, ancient Damascus steel blades, renowned for their strength and sharpness, have shown a complex microstructure of carbon nanotubes and iron carbide nanowires.…”

Natural Materials—Interesting Candidates for Carbon Nanomaterials

“…The presence of multi-walled carbon nanotubes (MWCNTs) in Damascus steel was the first observation of CNTs in ancient items dated back to the sixth-eighth centuries [1]. Recent discoveries on the existence of CNTs in ancient items as black coatings on the interior walls of pottery shards mined from Keeladi, Tamilnadu, India, dated back to the sixth-third centuries BC [2]. Moreover, the previous work claimed the sighting of CNTs in the Keeladi shards to be the oldest among the nanostructures reported so far from ancient artifacts around the world.…”

“…Hence, for large-scale CNTs production, the role of the catalyst is one of the major factors, while for this, only expensive transition metals such as Ni, Fe, Pt, V, Mo, Co, Y, and La are being actively used [57][58][59]. For example, in the case of CNTs in ancient items, the catalyst iron (Fe) might have originated from the soil, and then it could have favored the growth of CNTs upon heating the pottery at high temperatures [2]. Any go-ahead factor that reduced the cost of CNTs on a large scale will help in the CNTs applications for the end-user.…”