External electric field induced oxygen-driven unzipping of carbon nanotubes

Abstract

Based on density functional theory, the mechanisms for oxygen-driven unzipping of carbon nanotubes under electric field are presented. Under the control of external electric field, O adatoms will diffuse along the single-walled carbon nanotube from low potential to the high potential sites. The energy barrier of O adatoms diffusion gets lower while increasing the electric potential, thus enabling the O adatoms to diffuse to the higher potential sites more easily. And with quantities of O adatoms diffusing to the high potential sites, a linear epoxy chain is formed and the single-walled carbon nanotube will be unzipped into graphene nanoribbons automatically.

Effects of radical initiators, polymerization inhibitors, and other agents on the sonochemical unzipping of double-walled carbon nanotubes

“…[14][15][16][17][18][19] However, the corresponding mechanisms of the unzipping have rarely been studied theoretically, with most of them corresponding to oxidative (facilitated by the incorporation of oxygen atoms) 20,21) or reductive unzipping (promoted by the incorporation of hydrogen), 22,23) with other examples featuring the use of potassium permanganate 24) and electric fields. 25,26) Previously, we applied a sonochemical unzipping method of Jiao et al 27) to synthesize single-layer GNRs (sGNRs) from double-walled carbon nanotubes (DWNTs) 28) and single-walled carbon nanotubes (SWNTs), 29) with the corresponding mechanism rationalized as follows. 27) Heat treatment produces defects on nanotube sidewalls, and subsequent sonochemical treatment cuts these nanotubes open to afford GNRs, starting from the above defects.…”

Optical Unzipping of Carbon Nanotubes in Liquid Media

“…Various approaches have been developed to date to unzip CNTs to achieve GNRs, and some of the notable ones include: longitudinal unzipping via catalytic oxidation, plasma etching of partly embedded CNTs, gas-phase oxidation followed by sonication, surface-assisted coupling of molecular precursors into linear polyphenylenes and subsequent cyclodehydrogenation, self-organized growth on a templated silicon carbide substrate, and acid cutting along the folded edges via reaction with molecular hydrogen , or by electrochemical unzipping . Electric fields have also been proposed to unzip CNTs . Most of these techniques have their own limitations such as (a) production of irregular edges, (b) chemical impurity at the edges, (c) development of pores in ribbons, (d) scalability, (e) reproducibility, and (f) complexity of experimental design.…”

“…47 Electric fields have also been proposed to unzip CNTs. 48 Most of these techniques have their own limitations such as (a) production of irregular edges, (b) chemical impurity at the edges, (c) development of pores in ribbons, (d) scalability, (e) reproducibility, and (f) complexity of experimental design. Chemical synthesis, in particular, involving a combination of catalytic oxidation and thermal treatment, has marginal yield (as random defect formation most often triggers fragmentation of graphene sheets), and the obtained GNRs have oxygenated edges.…”