Unveiling the mystery of nucleation and growth of carbon nanotube and layered graphene inside carbon arc-discharge

TL;DR

This paper presents a model explaining how carbon nanotubes and layered graphene form during arc discharge, highlighting the role of thermal shock-induced crack microbranching and chemical reactions with plasma precursors.

Contribution

It introduces a new formation model based on anode erosion analysis, thermal shock effects, and chemical reactions that determine CNT or graphene growth.

Findings

Crack microbranching causes basal plane fragmentation.

Nanoribbons react with plasma precursors to form CNT or graphene.

Environmental viscosity and composition influence the resulting nanostructure.

Abstract

A model for the formation of carbon nanotubes (CNTs) and layered graphene in an arc discharge method is developed on the basis of observed erosion of graphite anode under various experimental conditions and analyses of the morphology of the eroded anode-surface, concerned cathode deposits and their constituents. It is predicted that, cold thermal shock, triggered by the rapid movement of the anode-spot, leads to crack microbranching at some selected locations on the anode-surface. These crack-microbranches cleave and fragment the basal planes of pairs of adjacent crystallites into curved graphitic nanoribbons with minimum two basal planes. These nanoribbons further react chemically with the C2 and C3 precursors present in the dusty carbon plasma and evolve either in the form of CNT or layered-graphene, depending on the viscosity and composition of the gaseous environment they are exposed to, just after getting detached from the anode.