Structural peculiarities of mesostructured carbons obtained by nanocasting ordered mesoporous templates via carbon chemical vapor or liquid phase infiltration routes

Mesostructured carbon materials were obtained by nanocasting MCM-48 and SBA-15 ordered mesoporous silica templates via two carbon infiltration routes: a liquid-phase process (LPI) using sucrose solution or a gas-phase chemical vapor infiltration (CVI) process using propene. The structural characteristics of the carbon replicas were investigated by synchrotron low-angle X-ray diffraction (LAXRD) analysis in combination with transmission electron microscopy (TEM). The materials obtained by the liquid-phase process demonstrated a long-range mesoscopic order at relatively low carbon loading (ca. 35 wt % in SiO2/C composite), with their structural elements being essentially shrunk compared to that of the templates. The CVI replicas at similar low infiltration content were found to be only partly organized within nanodomains, but at bigger carbon loading (ca. 50 wt %) highly ordered mesostructures displaying up to ten nonzero XRD reflections were obtained. Moreover, these materials were shown to have thicker frameworks faithfully replicating their templates. Particular features of the CVI replica of MCM-48 were an amorphous carbon shell on the external particle surface and a gradient of the nanoframework displacement. The carbon replicas of SBA-15 were characterized by a semitubular structure.