Thermal treatment-induced structural changes in graphene nanoribbons obtained from partially unzipped double-walled carbon nanotubes

Abstract

Graphene nanoribbons (GNRs) were synthesized by chemically unzipping double-walled carbon nanotubes (DWCNTs) followed by evaluation of their nanostructural changes upon thermal annealing. The formation of partially unzipped GNRs via the etching effect of a strong acid was confirmed using various analytical tools. The concentration of KMnO₄ showed a pronounced effect on the degree of oxidation and extent of exfoliation from the nanotube bundle, as well as the quality of GNRs. Thermally treated GNRs at 300 °C exhibited three different nanostructures (viz. graphitic onions, graphitic flakes, and amorphous carbon), whereas GNRs at 500 °C showed crystalline nanoparticles embedded in an amorphous matrix.