Studies on the correlation between nanostructure and pore development of polymeric precursor-based activated hard carbons: II. Transmission electron microscopy and Raman spectroscopy studies

In a previous study, we reported on activated polymer-based hard carbons (APHCs), which were prepared using CO2 activation and characterized according to activation conditions, including textural properties such as specific surface area and pore volume. This paper was focused on the correlation between nanostructure and pore development of APHCs by using Cs-corrected-field emission transmission electron microscopy (Cs-corrected FE-TEM) and Raman spectroscopy to supplement the in-depth explanation. In the TEM analysis, the APHCs were observed to contain slit-shaped pores (SPs) and little cylindrical pores (CPs). And Raman spectroscopy was used in order to determine the degree of development of the crystal size (L-a) in the APHCs. The size of L-a increased with increasing activation time until it was nearly 3 nm. These small crystallites might cause the SPs development, resulting in the high micropore volume of the APHCs. From a result of Raman analysis, it was confirmed that the L-a value and the ratio of I-D/I-G value were in a proportional relation. The reason for this relation is that the L-a value has grown up to about 3 nm, which is consistent with the Ferrari equation. (C) 2017 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.