Helical-ribbon carbon nanofibers produced on an industrial scale were successfully converted in highly functionalized graphene nanoplatelets by using a slight modification of the Hummers oxidation method. The duration of the oxidative process severely affected the interlayer spacing in the resulting nanoplatelets and, consequently, they showed very different exfoliation behavior. Therefore, it was possible to obtain a variety of graphene-related products through their ultrasonication or thermal treatments such as exfoliation-reduction by flash-pyrolysis in air at temperatures between 400 and 1000 °C or standard activation with CO2 at 800 °C. Detailed comparison of the functionalized carbon nanoplatelets, graphene oxides, reduced graphene oxides and activated carbon nanoplatelets reveals the wide spectrum of their properties with specific surface areas in the range of 4–500 m2 g−1, oxygen content from 38 to 5 wt% and different structural ordering. This study also underlines the impact of the structural, textural and chemical changes experienced by the carbon nanofibers along the various processes on the performance as supercapacitor electrodes. This preliminary study, based on cyclic voltammetry in 2 M H2SO4 aqueous electrolyte, is a summary of the strengths and weaknesses of the different graphene-related materials for this application. The helical-ribbon carbon nanofibers displayed only 10 F g−1, the capacitance of the functionalized graphene nanoplatelets greatly rose to 104 F g−1 with clear contributions from pseudocapacitance. Values around 100–120 F g−1 were found for the graphene oxides and activated graphene nanoplatelets although a marked resistive character is detected. Flash-pyrolysis at 1000 °C leads to lower capacitance (79 F g−1) but much quicker charge propagation. Among all these materials, the lower-cost functionalized graphene nanoplatelets displayed the better behavior for aqueous supercapacitors., Financial support from EU 7FP (Project Electrograph- 266391) and EU FP7-
ICT-2013-FET-FGRAPHENE Flagship Project (Nr. 604391) is gratefully
acknowledged., Peer reviewed

This research is focused in the missing link between the specific surface area of carbons surface and their electrochemical capacitance. Current protocols used for the characterization of carbons applied in supercapacitors electrodes induce inconsistencies in the values of the interfacial capacitance (in F m−2), which is hindering the optimization of supercapacitors. The constraints of both the physisorption of N2 at 77 K and the standard methods used for the isotherm analysis frequently lead to a misleading picture of the porosity. Moreover, the specific surface area of carbons loses their meaning when the supercapacitor operates with organic electrolytes and ionic liquids and the actual surface involved in charge storage has to be assessed by molecular probes suiting the critical dimensions of the ions. In the case of certain carbons such as graphene type-materials, the voltage-driven mechanism may facilitate the access of electrolyte ions to spaces between carbon layers, providing a larger area than that estimated by gas adsorption. Finally, the morphological and porous features of carbons can be extremely modified when they are processed in electrodes. Due to their impact, all these issues should not be neglected and the characterization protocols must be adapted for this specific application of carbons., Financial support from EU 7FP (Project Electrograph-266391) is gratefully
acknowledged. L.S. thanks the support from Programa Estatal de Promoción del
Talento y su Empleabilidad en I+D+i and European Social Fund-Youth Employment
Initiative.
The authors wish to thank Danubia Nanotech sro. (Slovakia) and Abalonyx AS
(Norway) for the gift of graphene materials of series GO-B and S77, respectively., Peer reviewed

By combining ab initio simulations with state-of-the-art electron microscopy and electron energy loss spectroscopy, we study the mechanism of electron beam damage in nitrogen-doped graphene and carbon nanotubes. Our results show that the incorporation of nitrogen atoms results in noticeable knock-on damage in these structures already at an acceleration voltage of 80 kV, at which essentially no damage is created in pristine structures at corresponding doses. Contrary to an early estimate predicting rapid destruction via sputtering of the nitrogen atoms, in the case of substitutional doping, damage is initiated by displacement of carbon atoms neighboring the nitrogen dopant, leading to the conversion of substitutional dopant sites into pyridinic ones. Although such events are relatively rare at 80 kV, they become significant at higher voltages typically used in electron energy loss spectroscopy studies. Correspondingly, we measured an energy loss spectrum time series at 100 kV that provides direct evidence for such conversions in nitrogen-doped single-walled carbon nanotubes, in excellent agreement with our theoretical prediction. Besides providing an improved understanding of the irradiation stability of these structures, we show that structural changes cannot be neglected in their characterization employing high-energy electrons., T.S. received support from the Finnish Foundation for Technology Promotion. T.S., H.J., and E.I.K. further acknowledge financial support from the CNB-E project of the Aalto MIDE program and from the LiBaCAM project of TEKES. J.K. and A.V.K. acknowledge financial support from Helsinki University Funds and Academy of Finland through several projects as well as CSC Ltd. Finland for computational resources. S.K., U.K., and J.C.M. acknowledge the financial support by the DFG (German Research Foundation) and the Ministry of Science, Research and the Arts (MWK) of Baden-Wuerttemberg in the frame of the SALVE (Sub Angstrom Low-Voltage Electron microscopy) project. V.S. acknowledges an EC Grant No. 266391 related to the project ELECTROGRAPH (FP7/2007-2013)., Peer reviewed