Mild sonochemical exfoliation of bromine-intercalated graphite: a new route towards graphene

TL;DR

This paper introduces a new mild sonochemical method combining bromine intercalation with sonication to produce high-quality graphene sheets efficiently from graphite.

Contribution

It presents a novel approach that significantly enhances graphite exfoliation by bromine intercalation, verified through spectroscopy and DFT calculations, leading to large, few-layer graphene sheets.

Findings

Bromine intercalation lowers interlayer binding energy by nearly ten times.

The method produces few-layer graphene with sizes up to 30 μm.

Suspensions contain a significant amount of few-layer graphene.

Abstract

A method to produce suspensions of graphene sheets by combining solution-based bromine intercalation and mild sonochemical exfoliation is presented. Ultrasonic treatment of graphite in water leads to the formation of suspensions of graphite flakes. The delamination is dramatically improved by intercalation of bromine into the graphite before sonication. The bromine intercalation was verified by Raman spectroscopy as well as by x-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) calculations show an almost ten times lower interlayer binding energy after introducing Br2 into the graphite. Analysis of the suspended material by transmission and scanning electron microscopy (TEM and SEM) revealed a significant content of few-layer graphene with sizes up to 30 $mu$m, corresponding to the grain size of the starting material.