Two-step splitting the expandable graphite for few-layer graphene

TL;DR

This paper presents a two-step method for producing few-layer graphene from expanded graphite using high-power sonication and thermal treatment, with detailed microscopy and spectroscopy analysis confirming the quality and mechanism.

Contribution

It introduces a novel two-step splitting process combining heating and sonication, optimizing the production of high-quality few-layer graphene.

Findings

Layer number reduced to less than 20 by heating to 1100°C

Few-layer graphene achieved with 5-minute sonication

Sheets are largely defect- and oxide-free

Abstract

Few-layer graphene sheets are prepared by splitting the expanded graphites using a high-power sonication. Atomic-level quantitative scanning transmission electron microscopy (Q-STEM) is employed to carry out the efficient layer statisticsm, enabling global optimization of the experimental conditions. A two-step splitting mechanism is thus revealed, in which the mean layer number was firstly reduced to less than 20 by heating to 1100{\deg}C and then tuned to the few-layer region by a 5-minute 104W/litre sonication. Raman spectroscopic analysis confirms the above mechanism and demonstrates that the sheets are largely free of defects and oxides.