In-situ XRD and dilatometry investigation of the formation of pillared graphene via electrochemical activation of partially reduced graphite oxide

The electrochemical activation reaction observed for oxygen rich graphitized carbons is known to irreversibly modify the properties of the material. After activation such carbons show for example an enhanced ion storage capability. In case of partially reduced graphite oxide (GOpr) this resulted in a specific capacitance of up 220 Fg(-1) and 300 Fg(-1) using an aprotic and a lithium electrolyte in acetonitrile, respectively. In the present study this activation mechanism is investigated by means of in-situ XRD and in-situ dilatometry in more detail. The combined information of the two in-situ techniques reveals the electrochemical activation to modify the interlayer distance of GOpr irreversibly. The resulting interlayer spacing of anodically activated GOpr was measured to be up to 14.7 angstrom in the discharged state, which equals slit-like micropores of up to 12.3 angstrom. This observed pillaring of the graphene layers to a distinct distance was traced down to a consolidation reaction within the first polarization of the electrode material. Combining the results from the in-situ characterizations with previous results from literature a reaction mechanism for the electrochemical activation reaction is proposed. These findings explain the achieved specific capacitance of GOpr and reveal a viable synthesis route to pillared graphene which can be useful for various applications. (C). 2014 Elsevier Ltd. All rights reserved.