Simultaneous Control of Morphology and Porosity in Nanoporous Carbon: Graphitic Mesoporous Carbon Nanorods and Nanotubules with Tunable Pore Size

We report on the use of simple chemical vapor deposition (CVD) nanocasting routes to simultaneously control the morphology, pore size, and graphitization in structurally well-ordered mesoporous carbons. Mesoporous silica SBA-15 rods were used as hard templates to nanocast mesostructured carbon nanorods and nanotubules with tunable pore size. The pore size of the carbons was tunable between 2 and 4.5 nm by simply using SBA-15 silica templates synthesized at various temperatures between 40 and 130 °C. Depending on the textural properties (and in particular the pore size) of the SBA-15 silica template, the particle morphology of the mesoporous carbon materials was changeable from nanorods (solid core) to hollow nanotubules. Small-pore SBA-15 silicas resulted in mesoporous carbon hollow tubes (nanotubules), whereas larger-pore silicas yielded solid-core rods. The nature of the SBA-15 silica did not affect the extent of graphitization. Greater levels of graphitization were, however, obtained for carbons prepared at higher CVD temperatures. To the best of our knowledge, this is the first successful attempt to control both the morphology and pore size of graphitic mesoporous carbons. Furthermore, this study demonstrates a new concept in which the pore size of the silica template plays a key role in directing the morphology of templated mesoporous carbon toward hollow particles (nanotubules) rather than solid-core particles (nanorods).