Showing papers by "Mildred S. Dresselhaus published in 2021"
TL;DR: The facile fabrication of novel supermolecule cucurbituril subnanoporous carbon materials and the smart design of "pores and balls" for high-performance energy storage systems are presented.
Abstract: It is quite challenging to prepare subnanometer porous materials from traditional porous precursors, and use of supramolecules as carbon sources was seldom reported due to the complex preparation and purification processes. We explore a facile one-pot method to fabricate supramolecular coordination compounds as carbon sources. The resultant CB[6]-derived carbons (CBC) have a high N content of 7.0-22.0%, surface area of 552-861 m2 g-1, and subnano/mesopores. The CBC electrodes have a narrow size distribution at 5.9 A, and the supercapacitor exhibits an energy density of 117.1 Wh kg-1 and a potential window of over 3.8 V in a two-electrode system in the ionic liquid (MMIMBF4) electrolyte with appropriate cationic (5.8 A) and anionic (2.3 A) diameter. This work presents the facile fabrication of novel supermolecule cucurbituril subnanoporous carbon materials and the smart design of "pores and balls" for high-performance energy storage systems.
36 citations
TL;DR: In this article, the impact of the Fermi energy of graphene and the phonon energy of the molecules was considered together for the first time in order to explain the enhancement of the Raman signal.
Abstract: The graphene-enhanced Raman scattering of Rhodamine 6G molecules on pristine, fluorinated and 4-nitrophenyl functionalized graphene substrates was studied. The uniformity of the Raman signal enhancement was studied by making large Raman maps. The relative enhancement of the Raman signal is demonstrated to be dependent on the functional groups, which was rationalized by the different doping levels of pristine, fluorinated and 4-nitrophenyl functionalized graphene substrates. The impact of the Fermi energy of graphene and the phonon energy of the molecules was considered together for the first time in order to explain the enhancement. Such approach enables to understand the enhancement without assuming anything about the uniformity of the molecules on the graphene surface. The agreement between the theory and our measured data was further demonstrated by varying excitation energy.