Measuring the lateral size of liquid-exfoliated nanosheets with dynamic light scattering

Abstract

We have developed an in-situ method to estimate the lateral size of exfoliated nanosheets dispersed in a liquid. Using standard liquid exfoliation and size-selection techniques, we prepared a range of dispersions of graphene, MoS 2 and WS 2 nanosheets with different mean lateral sizes. The mean nanosheet length was measured using transmission electron microscopy (TEM) to vary from ~40 nm to ~1 m. These dispersions were characterised using a standard dynamic light scattering (DLS) instrument. We found a well-defined correlation between the peak of the particle size distribution as outputted by the DLS instrument and the nanosheet length as measured by TEM. This correlation is consistent with the DLS instrument outputting the radius of the sphere with volume equal to the mean nanosheet volume. This correlation allows the mean nanosheet length to be extracted from DLS data.

Quantitative evaluation of delamination of graphite by wet media milling

“…In comparison with the oxidative route the surfactant-or solvent-assisted graphite exfoliation is much easier to handle and offers a process route for graphene production under mild conditions [20][21][22][23][24][25][26][27][28][29][30][31][32][33]. Single Layer Graphene and FLG have been produced by ultrasound-assisted graphite exfoliation in aqueous media in the presence of surfactants or in surfactant-free organic solvents [20][21][22][23][24][25][26][27][28][29][30][31][32][33]. The ultrasound-assisted wet chemical graphite exfoliation is simple and yields graphene flakes of good quality.…”

Edge and confinement effects allow in situ measurement of size and thickness of liquid-exfoliated nanosheets

“…In addition, measurement of nanosheet size is tedious, requiring time-consuming statistical microscopic analysis. While approximate in situ measurements of lateral size can be made optically 37 , no in situ method for nanosheet thickness measurement exists. To measure thickness, it is necessary to deposit nanosheets on surfaces, avoiding aggregation and use statistical Raman or atomic force microscopy (AFM) 38 .…”

Spinel type CoFe oxide porous nanosheets as magnetic adsorbents with fast removal ability and facile separation

“…The shape for Co 2.698 Fe 0.302 O 4 is asymmetric. This is also observed occasionally in Mustafa's work in which they used DLS to study lateral nanosheets which had been carefully processed with a size-selection technique [35]. The origin of multiple peaks was unclear and was described as spurious in their work [35].…”

“…3d lateral particles. Though in Mustafa's work they give an empirical equation to estimate the mean size of nanosheets by neglecting the geometric frictional coefficient and introducing uncertain constants, we do not further try to convert intensity to number/ volume particle size distribution because DLS instrument derives a non-linear intensity which limits us to obtain reliable size distribution [35]. Besides, the porous nature of materials studied in this work might also bring deviation.…”