Multi-scale characterization of graphenic materials synthesized by a solvothermal-based process: Influence of the thermal treatment

•Graphenic materials are synthesized by a solvothermal reaction and a pyrolysis under a nitrogen flow.•The characterization of the materials is carried out with multi-scale and complementary techniques.•The influence of the temperature and time of pyrolysis is studied and discussed.•The optimized parameters of the thermal treatment step are given.

Owing to its exceptional properties and a large range of possible applications, graphene gives rise to a great interest. Several major methods, as mechanical cleavage, liquid phase exfoliation of graphite and supported growth, have been developed these last years. However, it remains difficult to yield industrial quantities of graphene-based materials. Besides the research for the improvement of these major ways of synthesis, we focused on a much less common method: solvothermal synthesis. Graphenic powders can be obtained by a solvothermal reaction between ethanol and sodium followed by a thermal treatment step. We performed the solvothermal reaction and pyrolyzed the as-obtained sodium ethoxide with different temperature and time conditions, in order to study the influence of these two parameters on the final carbon-based sample. Various characterization techniques revealed the obtaining of graphenic materials with large aspect ratio, containing multi-layer graphene (MLG) regions. This study shows the strong influence of temperature and time of pyrolysis on purity, crystallinity and thickness of the samples, and goes toward an optimization of the thermal treatment step.

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