Fabrication of Highly-Aligned, Conductive, and Strong Graphene Papers Using Ultralarge Graphene Oxide Sheets

Abstract

This study demonstrates that large-size graphene oxide (GO) sheets can impart a tremendous positive impact on self-alignment, electrical conductivity, and mechanical properties of graphene papers. There is a remarkable, more than 3-fold improvement in electrical conductivity of the papers made from ultralarge GO sheets (with an average area of 272.2 μm(2)) compared to that of the small GO counterpart (with an average area of 1.1 μm(2)). The corresponding improvements in Young's modulus and tensile strength are equally notable, namely 320% and 280%, respectively. These improvements of bulk properties due to the large GO sheets are correlated to multiscale elemental and structural characteristics of GO sheets, such as the content of carboxyl groups on the GO edge, C/O ratio and Raman D/G-band intensity ratio of GO on the molecular-scale, and the degree of dispersion and stacking behavior of GO sheets on the microscale. The graphene papers made from larger GO sheets exhibit a closer-stacked structure and better alignment as confirmed by the fast Fourier transform analysis, to the benefits of their electrical conductivity and mechanical properties. The molecular dynamics simulation further elucidates that the enhanced intersheet interactions between large GO sheets play a key role in improving the Young's modulus of GO papers. The implication is that the said properties can be further improved by enhancing the intersheet stress transfer and electrical conduction especially through the thickness direction.

Size sorting of chemically modified graphene nanoplatelets

“…These results indicate that defects in the basal plane are not significantly different from S1 to S4. Moreover, defects caused by edge boundaries were not observed in our samples, in contrast to the decreased I D /I G observed/reported for ultra-large GO nanoplatelets (>100 μm 2 ) [20].…”

Scalable One‐Step Wet‐Spinning of Graphene Fibers and Yarns from Liquid Crystalline Dispersions of Graphene Oxide: Towards Multifunctional Textiles

“…[32,33] Other studies suggest a fast irreversible deoxygenation of graphene oxide under basic conditions. [34] However, irrespective of the mechanisms involved, employing alkaline coagulation baths results in the removal of oxygen multifunctionalities, [32][33][34][35] and consequently water from the graphene oxide sheets which in turn results in fiber coagulation and elimination of hydrogen bonds in between GO sheets and weakening of the inter-layer crosslinking. This water elimination leads to slightly lower mechanical properties compared to GO fibers coagulated in acetone bath.…”

“…It is pertinent to mention that there are different reduction processes that can be used to reduce graphene oxide. However as a general guideline, irrespective of the mechanisms involved, reducing graphene oxide by either employing annealing at moderate temperatures (upto 220 0 C) or alkaline coagulation baths results in the removal of oxygen multifunctionalities, [32][33][34][35] and consequently water from the graphene oxide sheets which in turn results in the elimination of hydrogen bonds in between GO sheets and weakening of inter-layer crosslinking. [35] This, in turn, results in inferior mechanical properties of reduced graphene oxide compared to parent graphene oxide.…”

Natural rubber/graphene oxide composites: Effect of sheet size on mechanical properties and strain-induced crystallization behavior

“…Generally, the GO papers with lower C/O atomic ratio have higher d-spacing, this can be explained by higher degree of functionalization. The GO sheets with more oxygenated functional groups can absorb more water through hydrogen bonding during film formation, inevitably increasing the interlayer distance to accommodate the water molecules [37].…”