Facile synthesis of high-quality graphene nanoribbons

Graphene nanoribbons have attracted attention because of their novel electronic and spin transport properties1,2,3,4,5,6, and also because nanoribbons less than 10 nm wide have a bandgap that can be used to make field-effect transistors1,2,3. However, producing nanoribbons of very high quality, or in high volumes, remains a challenge1,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18. Here, we show that pristine few-layer nanoribbons can be produced by unzipping mildly gas-phase oxidized multiwalled carbon nanotubes using mechanical sonication in an organic solvent. The nanoribbons are of very high quality, with smooth edges (as seen by high-resolution transmission electron microscopy), low ratios of disorder to graphitic Raman bands, and the highest electrical conductance and mobility reported so far (up to 5e2/h and 1,500 cm2 V−1 s−1 for ribbons 10–20 nm in width). Furthermore, at low temperatures, the nanoribbons show phase-coherent transport and Fabry–Perot interference, suggesting minimal defects and edge roughness. The yield of nanoribbons is ∼2% of the starting raw nanotube soot material, significantly higher than previous methods capable of producing high-quality narrow nanoribbons1. The relatively high-yield synthesis of pristine graphene nanoribbons will make these materials easily accessible for a wide range of fundamental and practical applications. Unzipping carbon nanotubes that have been mildly gas-phase oxidized results in graphene nanoribbons of very high quality.