title: Counter-ion dependent, longitudinal unzipping of multi-walled carbon nanotubes to highly conductive and transparent graphene nanoribbons.
abstract: Here we report for the first time, a simple hydrothermal approach for the bulk production of highly conductive and transparent graphene nanoribbons (GNRs) using several counter ions from K2SO4, KNO3, KOH and H2SO4 in aqueous media, where, selective intercalation followed by exfoliation gives highly conducting GNRs with over 80% yield. In these experiments, sulfate and nitrate ions act as a co-intercalant along with potassium ions resulting into exfoliation of multi-walled carbon nanotubes (MWCNTs) in an effective manner. The striking similarity of experimental results in KOH and H2SO4 that demonstrates partially damaged MWCNTs, implies that no individual K(+), SO4(2-) ion plays a key role in unwrapping of MWCNTs, rather this process is largely effective in the presence of both cations and anions working in a cooperative manner. The GNRs can be used for preparing conductive 16 kΩsq(-1), transparent (82%) and flexible thin films using low cost fabrication method.
authors.affiliation: 1] Physical & Materials Chemistry Division, National Chemical Laboratory, Pune 411 008 (India) [2] Nanoscale Science and Engineering Laboratory (NSEL) and Mechanical and Aerospace Engineering Department, Monash University, Clayton, VIC 3800, Australia.
authors.forename: Dhanraj B
authors.initials: DB
authors.lastname: Shinde
authors.affiliation: Nanoscale Science and Engineering Laboratory (NSEL) and Mechanical and Aerospace Engineering Department, Monash University, Clayton, VIC 3800, Australia.
authors.forename: Mainak
authors.initials: M
authors.lastname: Majumder
authors.affiliation: Central Electrochemical Research Institute (CSIR-CECRI), Karaikudi 630 006 (India).
authors.forename: Vijayamohanan K
authors.initials: VK
authors.lastname: Pillai
mesh_terms: D004553:Electric Conductivity; D006108:Graphite; D006878:Hydroxides / Q000737:chemistry; D008422:Materials Testing; D037742:Nanotubes, Carbon / Q000737:chemistry*; D009566:Nitrates / Q000737:chemistry; D017680:Potassium Compounds / Q000737:chemistry; D013431:Sulfates / Q000737:chemistry; D013464:Sulfuric Acids / Q000737:chemistry
chemical_list: D006878:Hydroxides; D037742:Nanotubes, Carbon; D009566:Nitrates; D017680:Potassium Compounds; D013431:Sulfates; D013464:Sulfuric Acids; C031512:potassium sulfate; D006108:Graphite; C033158:sulfuric acid; C023844:potassium nitrate; C029943:potassium hydroxide