Chemistry of zipping reactions in mesoporous carbon consisting of minimally stacked graphene layers

T Xia and T Yoshii and K Nomura and K Wakabayashi and ZZ Pan and T Ishii and H Tanaka and T Mashio and J Miyawaki and T Otomo and K Ikeda and Y Sato and M Terauchi and T Kyotani and H Nishihara, CHEMICAL SCIENCE, 14, 8448-8457 (2023).

DOI: 10.1039/d3sc02163g

The structural evolution of highly mesoporous templated carbons is examined from temperatures of 1173 to 2873 K to elucidate the optimal conditions for facilitating graphene-zipping reactions whilst minimizing graphene stacking processes. Mesoporous carbons comprising a few-layer graphene wall display excellent thermal stability up to 2073 K coupled with a nanoporous structure and three-dimensional framework. Nevertheless, advanced temperature-programmed desorption (TPD), X-ray diffraction, and Raman spectroscopy show graphene-zipping reactions occur at temperatures between 1173 and 1873 K. TPD analysis estimates zipping reactions lead to a 1100 fold increase in the average graphene- domain, affording the structure a superior chemical stability, electrochemical stability, and electrical conductivity, while increasing the bulk modulus of the framework. At above 2073 K, the carbon framework shows a loss of porosity due to the development of graphene-stacking structures. Thus, a temperature range between 1873 and 2073 K is preferable to balance the developed graphene domain size and high porosity. Utilizing a neutron pair distribution function and soft X-ray emission spectra, we prove that these highly mesoporous carbons already consist of a well-developed sp(2)-carbon network, and the property evolution is governed by the changes in the edge sites and stacked structures.

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