This research paper investigates unique black coatings found on pottery sherds excavated from Keeladi, India, dating back to the sixth century BC. Using Raman spectroscopy, transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS), the researchers identified the presence of single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes (MWCNTs), and layered sheets within the coating. Notably, the average diameter of the SWCNTs (0.6 ± 0.05 nm) is exceptionally small, close to the theoretical minimum. The findings suggest ancient knowledge of nanomaterial synthesis and highlight the remarkable stability and adhesion of these nanomaterials over 2600 years.
