Partially graphitic, high-surface-area mesoporous carbons from polyacrylonitrile templated by ordered and disordered mesoporous silicas

Abstract

Ordered and disordered mesoporous carbons synthesized from polyacrylonitrile using a templating method were heated under argon atmosphere at similar to 2470 K to partially graphitize them without the loss of mesoporosity. The high-temperature treatment led to a marked enhancement of graphitic ordering, which manifested itself in a narrowing of wide-angle XRD peaks, and in the appearance of domains of lateral dimensions 5-15 nm, consisting of stacked graphitic planes with interplanar spacing of similar to 0.34 nm. Raman spectroscopy provided evidence for the increased content of graphitic sp 2 carbon structures. The specific surface areas and total pore volumes of the carbons were 2 1 3 1 as high as 500-600 m(2) g(-1) and 0.8-1.8 cm(3) g(-1), respectively. These carbons had essentially no microporosity and their surface properties were similar to those of a graphitized carbon black Carbopack X. For ordered mesoporous carbons, the high-temperature treatment led to the loss of nanoscale periodicity, broadening of the pore size distribution (PSD) and similar to 40% decrease in the mesopore volume. In contrast, PSD and total pore volume of the disordered carbon were essentially unchanged. These results show that the high-temperature treatment of mesoporous carbons from PAN affords partially graphitic carbons with high specific surface areas and large pore volumes.