On the Nature of Defects in Liquid-Phase Exfoliated Graphene

M.V. BRACAMONTE; G.I. LACCONI; S. URRETA; L.E.F. FOA TORRES

Journal of Physical Chemistry C

American Chemical Society

Año: 2014 vol. 118 p. 15455 - 15459

Liquid-phase exfoliation is one of the most promising routes for large-scale production of multilayer graphene dispersions. These  dispersions, which may be used in coatings, composites, or paints, are  believed to contain disorder-free graphene multilayers. Here, we address the  nature of defects in such samples obtained by liquid-phase exfoliation of graphite powder in N-methyl-2-pyrrolidone. Our Raman spectroscopy data  challenge the assumption that these multilayers are free of bulk defects,  revealing that defect localization strongly depends on the sonication time. For short ultrasound times, defects are located mainly at the layer edges; they turn  out to build up in the bulk for ultrasonic times above 2 h. This knowledge may  help to devise better strategies to achieve high-quality graphene dispersions.