We introduce here results and discussion on a recent strategy to prepare carbonaceous materials related to graphene (graphene-like materials) from natural precursors such as proteins or carbohydrates, assembled to different types of clay minerals. Thermal treatment at relatively low temperature, below 800°C, in the absence on oxygen and without requiring the presence of reducing agents, could transform clay-based bionanocomposites into graphene materials that remain supported on the involved porous substrate (layered or fibrous clays). The resulting composite materials have been characterized by spectroscopic tools (Raman and XPS), XRD patterns, FE-SEM and TEM microscopies, nitrogen adsorption isotherms, and electrical conductivity measurements. One of the most interesting features is the good electronic conductivity measured in the presence of the inorganic matrix, which usually shows insulating behavior. Therefore, these composites based on carbonaceous materials supported on clays, could directly receive applications related to energy storage (electrodes in electrochemical lithium batteries and supercapacitors), as well as adsorbent for use as hydrogen vector. One of the controverted points of this research is related with the mechanism of transformation of the biomolecule precursors into graphene-like compounds. The application of various in situ techniques (TG-MS, GC-MS, Raman-Operando and EIS) to follow the transformation of caramel-silicate reveals the formation of diverse polyaromatic compounds during the process. These species are further condensed till they reach the formation of imperfect graphene flakes of irregular shape and variable size that remain assembled to the clay matrix. The generation of graphene in the presence of clays using biomass as carbon precursors, represents an alternative to conventional methods based on the “classical” way involving oxidation-reduction of graphite. References: Ruiz-Hitzky E., Darder M., Fernandes F.M., Zatile E., Palomares F.J., Aranda P., 2011, Adv. Mater. 23, 5250. C. Ruiz-García, M. Darder, P. Aranda, E. Ruiz-Hitzky, J. Mater. Chem. A 2 (2014) 2009. Acknowledgements: Authors thank the CICYT (Spain, project MAT2012-31759) and grant agreement n°604391 (Graphene Flagship, EU).

Clay-based nanocomposites for supported graphene production

251st National Meeting (2016)

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