Graphene Oxide-Assisted Liquid Phase Exfoliation of Graphite into Graphene for Highly Conductive Film and Electromechanical Sensors.
Here, we report a new method to prepare graphene from graphite by the liquid phase exfoliation process with sonication using graphene oxide (GO) as a dispersant. It was found that GO nanosheets act a as surfactant to the mediated exfoliation of graphite into a GO-adsorbed graphene complex in the aqueous solution, from which graphene was separated by an additional process. The preparation of isolated graphene from a single to a few layers is routinely achieved with an exfoliation yield of up to higher than 40% from the initial graphite material. The prepared graphene sheets showed a high quality (C/O ∼ 21.5), low defect (ID/IG ∼ 0.12), and high conductivity (6.2 × 10(4) S/m). Moreover, the large lateral size ranging from 5 to 10 μm of graphene, which is believed to be due to the shielding effect of GO avoiding damage under ultrasonic jets and cavitation formed by the sonication process. The thin graphene film prepared by the spray-coating technique showed a sheet resistance of 668 Ω/sq with a transmittance of 80% at 550 nm after annealing at 350 °C for 3 h. The transparent electrode was even greater with the resistance only 66.02 Ω when graphene is deposited on an interdigitated electrode (1 mm gap). Finally, a flexible sensor based on a graphene spray-coating polydimethylsiloxane (PDMS) is demonstrated showing excellent performance working under human touch pressure (<10 kPa). The graphene prepared by this method has some distinct properties showing it as a promising material for applications in electronics including thin film coatings, transparent electrodes, wearable electronics, human monitoring sensors, and RFID tags.
School of Chemical Engineering, The University of Adelaide , Adelaide, 5005 North Terrace, South Australia.
Tran Thanh
TT
Tung
School of Chemical Engineering, The University of Adelaide , Adelaide, 5005 North Terrace, South Australia.
Jeongha
J
Yoo
School of Chemical Engineering, The University of Adelaide , Adelaide, 5005 North Terrace, South Australia.
Faisal K
FK
Alotaibi
School of Chemical Engineering, The University of Adelaide , Adelaide, 5005 North Terrace, South Australia.
Md J
MJ
Nine
School of Chemical Engineering, The University of Adelaide , Adelaide, 5005 North Terrace, South Australia.
Ramesh
R
Karunagaran
School of Chemical Engineering, The University of Adelaide , Adelaide, 5005 North Terrace, South Australia.
Melinda
M
Krebsz
School of Chemical Engineering, The University of Adelaide , Adelaide, 5005 North Terrace, South Australia.
Giang T
GT
Nguyen
School of Chemical Engineering, The University of Adelaide , Adelaide, 5005 North Terrace, South Australia.
Diana N H
DN
Tran
Smart Plastics Group, Bretagne Loire University (UBL) , IRDL CNRS 3744-UBS, Lorient 56100, France.
Jean-Francois
JF
Feller
School of Chemical Engineering, The University of Adelaide , Adelaide, 5005 North Terrace, South Australia.
Dusan
D
Losic
conductive film; electronic devices; exfoliation; graphene; pressure sensors; wearable electronics