Modifying the Size of Ultrasound-Induced Liquid-Phase Exfoliated Graphene: From Nanosheets to Nanodots

Accès libre Peer reviewed | |
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Version acceptée pour publication (post-print auteur) | |
Paternité - Pas d'utilisation commerciale [CC] [BY] [NC] | |
Auteurs |
Artur Ciesielski Sébastien Haar Alessandro Aliprandi Mohamed El Garah Giulia Tregnago Giovanni F. Cotella Mirella El Gemayel Fanny Richard Haiyan Sun Franco Cacialli Francesco Bonaccorso Paolo Samorì |
Langue |
en |
Volume |
10 |
Numéro |
12 |
Page de début |
10768 |
Page de fin |
10777 |
Date de première publication |
2016-11-15 |
ISSN |
1936-0851 |
Titre de la source (revue, livre…) |
ACS Nano |
Résumé |
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 Show moreUltrasound-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. Show less |
DOI | 10.1021/acsnano.6b03823 |
Titre abrégé de la source |
ACS Nano |
Type de publication |
ACL |
Domaine |
Chimie/Matériaux |
Audience |
International |
URL | https://univoak.eu/islandora/object/islandora:57363 |