Determination of quantitative structure-property and structure-process relationships for graphene production in water

Abstract

A scalable method for graphene and few-layer graphene (FLG) production by graphite delamination in aqueous solutions of the nonionic surfactant TWEEN ® 80 (TW80) using stirred-media mills is presented. Delaminated product analysis using statistical Raman spectroscopy yielded extensive processing-structure-property relationships that revealed how stress intensity and specific energy input, i.e., the process parameters, govern the yield of graphene production and defect formation. The dispersed carbon concentration increased but the content and the quality of the FLG product decreased sharply with higher specific energy input. The FLG content of the product was up to 90%, especially for low specific energy input. Moreover, Raman analyses revealed that stress intensities greater than about 1 nJ were related to significant defect formation in the product particles. Another key parameter for graphene production is solvent viscosity. The FLG concentration in the product increased by a factor of 10 when the solvent's viscosity was increased from 1 to 6 mPa·s because shear-and friction-induced delamination was enhanced and in-plane fracture was reduced due to dampening of bead motion. Based on the processing-structure-property relationships found, we propose that the delamination process can be designed in such way that the product consists, almost totally, of FLG and that single-layer graphene is produced. The scalability of graphene production by stirred-media delamination was demonstrated when an increase in the batch size from 0.2 to 2 L had no significant effect on product quality.

Delamination of graphite in a high pressure homogenizer

“…17, 18 Khan et al centrifuged the suspension with lower relative centrifugal force than in this work and therefore more product remained dispersed.…”

“…17,18,37,38 In addition, AUC provides detailed insights into the sedimentation behaviour of the obtained platelet suspensions and allows the determination of lateral dimensions directly in solution, if the ake height is known.…”

Progress in Multidimensional Particle Characterization

“…(Ahmad et al, 2017)). Statistical composition mapping via Raman spectroscopy, supported by atomic force microscopy (AFM) co-localization, is very promising to study size-dependent composition in such particulate products (Nacken T. et al, 2015).…”

“…While the lateral geometry of graphene sheets is easily accessible by AFM, the measured height of the sheets may be influenced by adsorbates at the surface. Using complementary Raman spectroscopy allows accurately determining the number of sheets (up to 5 layers) and their defect states (Eigler et al, 2014;Nacken T. et al, 2015). As the signals of both techniques are evaluated at the same sample position by co-localization, true multidimensional property distributions in terms of lateral sheet size and number of graphene sheets (thickness) can be acquired.…”

Optimized polybutylene terephthalate powders for selective laser beam melting

“…Wet grinding as a top-down approach is established for the production of micro-and even nanoparticles for a variety of materials (Damm et al, 2013;Romeis et al, 2014;Nacken et al, 2015;Ito et al, 2016). However, typically irregular-shaped, cohesive particles are obtained that cannot be employed in LBM without further modification.…”