Highly conducting graphene sheets and Langmuir–Blodgett films

Abstract

Graphene is an intriguing material with properties that are distinct from those of other graphitic systems. The first samples of pristine graphene were obtained by 'peeling off' and epitaxial growth. Recently, the chemical reduction of graphite oxide was used to produce covalently functionalized single-layer graphene oxide. However, chemical approaches for the large-scale production of highly conducting graphene sheets remain elusive. Here, we report that the exfoliation-reintercalation-expansion of graphite can produce high-quality single-layer graphene sheets stably suspended in organic solvents. The graphene sheets exhibit high electrical conductance at room and cryogenic temperatures. Large amounts of graphene sheets in organic solvents are made into large transparent conducting films by Langmuir-Blodgett assembly in a layer-by-layer manner. The chemically derived, high-quality graphene sheets could lead to future scalable graphene devices.

A low-temperature method to produce highly reduced graphene oxide

“…The GO sample showed significant weight loss with an onset temperature at slightly 4100°C, which was attributed to the elimination of interlamellar water, followed by loss of oxygen from the GO platelets themselves at slightly higher temperatures. RGO Na-NH3 showed much higher thermal stability because of the more complete de-oxygenation and better graphitization with enhanced van der Waals forces between layers [34][35][36] .…”

“…Although a prominent D peak is typically an indication of disorder in the Raman of peeled graphene, our observations are consistent with previous reports of RGO materials 28 . A greater ratio of the Raman D/G intensity of the RGO Na-NH 3 films compared with the GO film indicates an increase in the number of smaller sp 2 domains 33,34 .…”

Paper‐Based Electrodes for Flexible Energy Storage Devices

“…These studies pave a way for fabricating graphene and graphene‐based films. Graphene dispersions or graphene‐based hybrid materials suspension can be well processed into electrodes using various techniques, including dip coating,113 rod coating,114 spray coating,115 inkjet printing,116 spin coating,117 screen printing,118 gravure printing,119 blade coating,120 electrospinning,121 electrodeposition,122 vacuum filtration,123 drop casting,124 interfacial deposition,124 Langmiur‐Blodgett deposition125 and layer‐by‐layer assembly 126. Depends on the targeted properties and size of the graphene electrode, different approaches should be used 102…”

Liquid Phase Production of Graphene by Exfoliation of Graphite in Surfactant/Water Solutions

“…These defects are virtually impossible to remove completely; even after annealing at 1000 o C, residual C=O and C-O bonds are observed by X-ray photoelectron spectroscopy 7 . Even mild chemical treatments, involving soaking in oleum, result in non-negligable oxidisation which requires annealing at 800 o C to remove 9 .…”