Hybrid Low‐Dimensional Carbon Allotropes Formed in Gas Phase

Abstract

Graphene, carbon nanotubes (CNTs) and fullerenes are the basic set of low-dimensional carbon allotropes. The latter two arise from the former by selective removal and addition of carbon atoms. Nevertheless, given their morphological disparities, the production of each is typically devised from entirely different starting points. Here, it is demonstrated that all three allotropes can nucleate from (pseudo-)spherical, nanometer-sized transition metal clusters in a gas-suspension when the chemical conditions are favorable. The experimental results indicate that graphitic carbon embryos nucleate on the catalyst particles and sometimes transform into 2D graphene flakes through chain polymerization of carbon fragments forming in the surround gas atmosphere. It is further shown that hydrogenation reactions play an essential role by stabilizing the emerging flakes by mitigating the pentagon and heptagon defects that lead into evolution of fulleroids. Ab initio molecular dynamics simulations show that the ratio of hydrogen to carbon in the reaction is a key growth parameter. Since structural formation takes place in a gas-suspension, graphene accompanied by fullerenes and singlewalled CNTs can be deposited on any surface at ambient temperature with arbitrary layer thicknesses. This provides a direct route for the production and deposition of graphene-based hybrid thin films for various applications.

Initial competing chemical pathways during floating catalyst chemical vapor deposition carbon nanotube growth

“…43 More recently, ethylene was used as a precursor to simultaneously synthesize fullerenes, SWCNTs, and graphene in the gas-phase, and the use of either ferrocene, cobaltocene, or nickelocene did not affect the synthesized product in any way, aside from yield. 69 Moreover, while Fc-derived Fe catalysts have been shown to produce a higher SWCNT yield via FCCVD, compared to derived Co and Ni catalyst particles, the…”

Bithiophene as a Sulfur-Based Promotor for the Synthesis of Carbon Nanotubes and Carbon-Carbon Composites

“…We wish to stress that the obtained SWCNT/few-layer graphene composites might be of significant interest for various applications [ 43 ]. For example, such hybrid membranes should provide increased performance as EUV pellicles [ 44 ] or X-ray protective membranes.…”

Cutting Methods and Perspectives of Carbon Nanotubes

“…The combination of ultrasonic cutting and acid oxide cutting is an effective cutting technology, which has the advantages of a high cutting efficiency and small sidewall damage. ,, For example, a method of cutting SWCNTs in a H 2 SO 4 and HNO 3 mixture is based on high-power ultrasound. The samples were prepared by three different methods: gas-phase catalysis (H-SWCNT), − chemical vapor deposition (C-SWCNT), − and arc discharge (A-SWCNT). − A treatment at low temperatures (below 8 °C) with mixtures of concentrated H 2 SO 4 and HNO 3 (3:1, 95 and 59% by volume, respectively) was used to obtain minimum carbon loss and yield of next to 100% short-SWCNTs (50–200 nm long). A low concentration of mixed acid and low processing temperature (<8 °C) decreased the sidewall oxidation rate of CNTs, and a high ultrasonic power density (3 W cm –3 ) increased the cutting rate of CNTs at new defects.…”