Graphene-like materials supported on sepiolite clay synthesized at relatively low temperature

abstract

The preparation of solids with graphitic structure usually requires synthesis procedures using very high temperatures. In this work, a comparative study involving different experimental strategies of synthesis at relatively low temperature was carried out to obtain graphene-like materials supported on microporous sepiolite (SEP) clay. The final objective was the optimization of the development of new clay-graphitic nanostructured materials to achieve porous solids while saving energy and time during the preparation stages. The pyrolysis of sucrose (SUC), used as carbon precursor, was accomplished by microwave (MW) pyrolysis or tube furnace (TF) pyrolysis at 200 or 500 degrees C followed by a hydrothermal carbonization (HTC) step. The resulting carbon-clay nanoarchitectures were characterized by Raman and Infrared spectroscopy, X-ray diffraction, elemental analysis, electron microscopy, and nitrogen adsorption-desorption isotherms. The MW200 and TF200 treatments caramelized SUC and the post-HTC step was fundamental to obtain porous carbonaceous materials. The TF500 pyrolysis produced predominantly crystalline carbon, while the MW500 pyrolysis formed an amorphous material. Moreover, the high-resolution transmission electron microscopy observations of TF500 sample revealed a crystalline material with a d-spacing of 0.33 nm, matching the graphitic lattice. All the treatment conditions performed at 500 degrees C i.e., MW or TF followed or not by HTC, resulted in mesoporous carbons with a specific surface area above 200 m(2) g(-1). The MW pyrolysis saved 100 min of the reaction time in comparison to TF pyrolysis to obtain the carbonaceous porous materials.

keywords

HYDROTHERMAL CARBONIZATION; RAMAN-SPECTROSCOPY; CARBONS; POLYACRYLONITRILE; GRAPHITE; POROSITY

subject category

Chemistry; Materials Science

authors

Barra, A; Lazar, O; Mihai, G; Bratu, C; Ruiz-Garcia, C; Darder, M; Aranda, P; Enachescu, M; Nunes, C; Ferreira, P; Ruiz-Hitzky, E

Groups

G2 - Photonic, Electronic and Magnetic Materials
G4 - Renewable Materials and Circular Economy

Projects

CICECO - Aveiro Institute of Materials (UIDB/50011/2020)

CICECO - Aveiro Institute of Materials (UIDP/50011/2020)

Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)

acknowledgements

This work was developed within the scope of the project CICECO-Aveiro Institute of Materials (UIDB/50011/2020, UIDP/50011/2020 & LA/P/0006/2020) financed by national funds by the Fundacao para a Ciencia e a Tecnologia (FCT) /Ministerio da Educacao e Cultura (MEC) through the program PIDDAC (Programa de Investimento e Despesa de Desenvolvimento da Administracao Central) . AB is thankful to FCT for grant SFRH/BD/148856/2019. CN is grateful to Portuguese national funds (OE) , through FCT, I.P., in the scope of the framework contract foreseen in the numbers 4, 5 and 6 of the article 23, of the Decree-Law 57/2016, of August 29, changed by Law 57/2017, of July 19. ERH, PA and MD gratefully acknowledge the financial support from MCIN/AEI/10.13039/501100011033/and European Regional Development Fund (ERDF) una manera de hacer Europa (MAT2015-71117-R project) and MCIN/AEI/10.13039/501100011033 (Spain, project PID2019-105479RB-I00) . These last authors and CRG, also thanks L.M. Cuadra (MNCN-CSIC) and I. Such (Research Support Services at the University of Alicante, Spain) for their help in obtaining the MS spectra, as well as M.A. Banares (ICP-CSIC) for the data acquisition of the in situ Raman spectra.This research was funded by ECSEL JU under the following grant agreements: No. 876124 (BEYOND5) and No. 875999 (IT2) . The JU receives support from the European Union's Horizon 2020 research and innovation program and Germany, Belgium, Sweden, Austria, Romania, France, Poland, Israel, Switzerland, Netherlands, Hungary, United Kingdom. This work is financially supported by the Romanian Ministry of Research, Innovation and Digitalization, under the following ECSEL-H2020 Projects: BEYOND5-Contract no. 12/1.1.3/31.07.2020, POC-SMIS code 136877 and IT2-Contract. no. 11/1.1.3H/06.07.2020, POC-SMIS code 136697. The authors acknowledge the COST action NET-PORE CA20126 supported by COST (European Cooperation in Science and Technology) .