Xia Tian, Yoshii Takeharu, Nomura Keita, Wakabayashi Keigo, Pan Zheng-Ze, Ishii Takafumi, Tanaka Hideki, Mashio Takashi, Miyawaki Jin, Otomo Toshiya, Ikeda Kazutaka, Sato Yohei, Terauchi Masami, Kyotani Takashi, Nishihara Hirotomo
Institute of Multidisciplinary Research for Advanced Materials, Tohoku University 2-1-1 Katahira, Aoba-ku Sendai Miyagi 980-8577 Japan
Advanced Institute for Materials Research (WPI-AIMR), Tohoku University 2-1-1 Katahira, Aobaku Sendai Miyagi 980-8577 Japan.
Chem Sci. 2023 Jul 18;14(32):8448-8457. doi: 10.1039/d3sc02163g. eCollection 2023 Aug 16.
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-carbon network, and the property evolution is governed by the changes in the edge sites and stacked structures.
研究了高度介孔模板碳在1173至2873 K温度范围内的结构演变，以阐明促进石墨烯拉链反应同时最小化石墨烯堆叠过程的最佳条件。由几层石墨烯壁组成的介孔碳在高达2073 K的温度下表现出优异的热稳定性，并具有纳米多孔结构和三维框架。然而，先进的程序升温脱附（TPD）、X射线衍射和拉曼光谱表明，石墨烯拉链反应发生在1173至1873 K之间的温度。TPD分析估计，拉链反应导致平均石墨烯域增加1100倍，使该结构具有卓越的化学稳定性、电化学稳定性和导电性，同时提高了框架的体积模量。在2073 K以上，由于石墨烯堆叠结构的发展，碳框架显示出孔隙率的损失。因此，1873至2073 K的温度范围更有利于平衡发达的石墨烯域尺寸和高孔隙率。利用中子对分布函数和软X射线发射光谱，我们证明这些高度介孔碳已经由一个发育良好的sp碳网络组成，并且性能演变受边缘位点和堆叠结构变化的支配。
