Measurements of the Electrical Conductivity of Monolayer Graphene Flakes Using Conductive Atomic Force Microscopy

Abstract

The intrinsic electrical conductivity of graphene is one of the key factors affecting the electrical conductance of its assemblies, such as papers, films, powders, and composites. Here, the local electrical conductivity of the individual graphene flakes was investigated using conductive atomic force microscopy (C-AFM). An isolated graphene flake connected to a pre-fabricated electrode was scanned using an electrically biased tip, which generated a current map over the flake area. The current change as a function of the distance between the tip and the electrode was analyzed analytically to estimate the contact resistance as well as the local conductivity of the flake. This method was applied to characterize graphene materials obtained using two representative large-scale synthesis methods. Monolayer graphene flakes synthesized by chemical vapor deposition on copper exhibited an electrical conductivity of 1.46 ± 0.82 × 106 S/m. Reduced graphene oxide (rGO) flakes obtained by thermal annealing of graphene oxide at 300 and 600 °C exhibited electrical conductivities of 2.3 ± 1.0 and 14.6 ± 5.5 S/m, respectively, showing the effect of thermal reduction on the electrical conductivity of rGO flakes. This study demonstrates an alternative method to characterizing the intrinsic electrical conductivity of graphene-based materials, which affords a clear understanding of the local properties of individual graphene flakes.

Recent trends in two-dimensional graphene derivatives-based composites: Review on synthesis, properties and applications

“…52 It is worth mentioning, that the highest electrical conductivity values reported in research literature for some graphene derivatives, including few-layer graphene, thermally reduced graphene oxide (TRGO) and chemically reduced graphene oxide (CRGO) are 100,000, 65 72,700 66 and 30,400 67 S/m, respectively. Thus, FLG, TRGO and CRGO show lower electrical conductivities than that of single-layer graphene 61 by 15, 21 and 49 times, respectively. The weak interlayer bonding in FLG limits the charge carriers’ mobility and consequently the electrical conductivity is reduced.…”

Lightning Strike Protection: Current Challenges and Future Possibilities

“…Due to these properties, it is of high interest for the aeronautical industry in various fields of application such as de-icing [ 22 ], flame inhibition [ 23 ], water uptake, and corrosion protection [ 24 , 25 ]. With an electrical conductivity of about 1.46 × S/m [ 26 ], a thermal conductivity of 4.84 × W/mK [ 27 ], and a density of g/cm 3 , single-layer graphene sheets appear an ideal solution for LSP. Although these properties are promising, technical realisation of graphene-based LSP systems appears challenging.…”

“…An emerging field of 2DM is MXenes (early transition metal carbides and nitrides) with their currently most prominent material Ti 3 C 2 T x [ 56 ]. Recent material-synthesis-related studies [ 57 ] were able to improve MXene conductivity to 2.4 × S/m, being superior to graphene sheets (1.46 × S/m [ 26 ]) and exhibiting breakdown currents comparable to graphene (1.2 × V/cm 2 ) [ 58 ]. In addition, MXenes can express a variety of surface terminations, which can be modified to improve adhesion to the matrix, but they carry the drawback of a higher density (4.21 g/cm 3 [ 59 ]) compared to graphene.…”

Enhanced Electromagnetic Shielding and Thermal Conductive Properties of Polyolefin Composites with a Ti3C2Tx MXene/Graphene Framework Connected by a Hydrogen-Bonded Interface

“…The family of polyolefins, such as polyethylene (PE) and polypropylene (PP), is one of the most common thermoplastic polymers and has been extensively applied in the electronic industry . Polyolefins possess many advantages such as versatility, light weight, and chemical inertness; however, they are almost transparent to electromagnetic waves (EMI shielding effectiveness (EMI SE): < 1 dB) , and have low thermal conductivity (0.2–0.5 W m –1 K –1 ). , In order to simultaneously promote these two properties, a variety of nanofillers have been employed to prepare polyolefin composites, including silver/copper nanoparticles or nanowires, − MXene nanosheets, , and carbon nanotubes or graphene. − In particular, the major role of two-dimensional materials, graphene, shows the most promise due to the high basal-plane electrical conductivity (10 5 –10 6 S m –1 ) , and thermal conductivity ((3.5–5.3) × 10 3 W m –1 K –1 ). , …”