Conductivity Maximum in 3D Graphene Foams

Abstract

In conventional foams, electrical properties often play a secondary role. However, this scenario becomes different for 3D graphene foams (GrFs). In fact, one of the motivations for synthesizing 3D GrFs is to inherit the remarkable electrical properties of individual graphene sheets. Despite immense experimental efforts to study and improve the electrical properties of 3D GrFs, lack of theoretical studies and understanding limits further progress. The causes to this embarrassing situation are identified as the multiple freedoms introduced by graphene sheets and multiscale nature of this problem. In this article, combined with transport modeling and coarse-grained molecular dynamic (MD) simulations, a theoretical framework is established to systematically study the electrical conducting properties of 3D GrFs with or without deformation. In particular, through large-scale and massive calculations, a general relation between contact area and conductance for two van der Waals bonded graphene sheets is demonstrated, in terms of which the conductivity maximum phenomenon in GrFs is first theoretically proposed and its competition mechanism is explained. Moreover, the theoretical prediction is consistent with previous experimental observations.

Synthesis of Polyacetylene-like Modified Graphene Oxide Aerogel and Its Enhanced Electrical Properties

“…The bulk electrical conductivity (Table 3) of the polymer-modified graphene oxide aerogel was (sample GOA6) 128 S/cm, about 2–3 orders of magnitude higher than those reported for other 3D graphene materials prepared with other methods. 48,50 It is our opinion that this extraordinarily high conductivity and not the intuitively U-I behavior (Figure 10) is due to a rearrangement in the network morphology (many ripples in fixed positions) of the graphene oxide sheets in a 3D system. In congruence with the morphological differences, a substantial reduction in resistance at the connections between graphene sheets compared to those at the van der Waals bonds along with the use of an intrinsically conducting polymer could increase the mobility of the electrons and phonons.…”

Recent Progress in Graphene/Polymer Nanocomposites

“…Graphene with ultrahigh electrical conductivity is a promising candidate to improve the conductivity of insulating matrices. [ 86–91 ] The intrinsic electrical conductivity of graphene is influenced by the layer number, [ 92–94 ] defects, [ 95–97 ] and lateral size [ 92–99 ] of graphene, as shown in Figure . Nirmalraj et al.…”

“…Therefore, it is crucial to make it aligned in the nanocomposites in order to achieve excellent electrical performance. [ 82–129 ] Recently, graphene aerogels with anisotropic microstructure were extensively investigated. Li et al.…”

Bacterial cellulose/graphene oxide aerogels with enhanced dimensional and thermal stability

“…The reduction with NH3 at 220 ºC is more favourable to produce high BC/rGO conductors when compared to the ones reduced with N2H4 (Table 2). After the reduction treatments, a large fraction of the oxygen-containing groups were removed and π-π bonds were restored on the surface of rGO, which facilitates the electrons transportation (Beeran P. T. et al, 2016;F. Liu, Wang, & Tang, 2018;Pottathara et al, 2019;Zhan, Xiong, Yang, Shi, & Yang, 2019).…”