Ciesielski, A;
Haar, S;
Aliprandi, A;
El Garah, M;
Tregnago, G;
Cotella, GF;
El Gemayel, M;
... Samorì, P; + view all
(2016)
Modifying the Size of Ultrasound-Induced Liquid-Phase Exfoliated Graphene: From Nanosheets to Nanodots.
ACS Nano
, 10
(12)
pp. 10768-10777.
10.1021/acsnano.6b03823.
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Abstract
Ultrasound-induced liquid-phase exfoliation (UILPE) is an established method to produce single- (SLG) and few-layer (FLG) graphene nanosheets starting from graphite as a precursor. In this paper we investigate the effect of the ultrasonication power in the UILPE process carried out in either N-methyl-2-pyrrolidone (NMP) or ortho-dichlorobenzene (o-DCB). Our experimental results reveal that while the SLGs/FLGs concentration of the NMP dispersions is independent of the power of the ultrasonic bath during the UILPE process, in o-DCB it decreases as the ultrasonication power increases. Moreover, the ultrasonication power has a strong influence on the lateral size of the exfoliated SLGs/FLGs nanosheets in o-DCB. In particular, when UILPE is carried out at ∼600 W, we obtain dispersions composed of graphene nanosheets with a lateral size of 180 nm, whereas at higher power (∼1000 W) we produce graphene nanodots (GNDs) with an average diameter of ∼17 nm. The latter nanostructures exhibit a strong and almost excitation-independent photoluminescence emission in the UV/deep-blue region of the electromagnetic spectrum arising from the GNDs' intrinsic states and a less intense (and strongly excitation wavelength dependent) emission in the green/red region attributed to defect states. Notably, we also observe visible emission with near-infrared excitation at 850 and 900 nm, a fingerprint of the presence of up-conversion processes. Overall, our results highlight the crucial importance of the solvent choice for the UILPE process, which under controlled experimental conditions allows the fine-tuning of the morphological properties, such as lateral size and thickness, of the graphene nanosheets toward the realization of luminescent GNDs.
| Type: | Article |
|---|---|
| Title: | Modifying the Size of Ultrasound-Induced Liquid-Phase Exfoliated Graphene: From Nanosheets to Nanodots |
| Location: | United States |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1021/acsnano.6b03823 |
| Publisher version: | http://dx.doi.org/10.1021/acsnano.6b03823 |
| Language: | English |
| Additional information: | This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Nano, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see: http://dx.doi.org/10.1021/acsnano.6b03823. |
| Keywords: | graphene, liquid-phase exfoliation, nanodots, photoluminescence |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/1534451 |
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