Generalized and Facile Synthesis Approach to N-Doped Highly Graphitic Mesoporous Carbon Materials

Abstract

The synthesis and characterization of porous graphitic carbon materials via chemical vapor deposition (CVD) using various mesoporous silicas including SBA-12, SBA-15, MCM-48, MCM-41, and HMS as solid templates is presented. The use of acetonitrile as carbon precursor generates N-doped carbon (CNx type) materials with nitrogen content of ca. 8 wt %. The N-doped carbon materials exhibit both well-ordered mesoporosity and high levels of graphitic character. The mesostructural ordering and extent of graphitization depend on the CVD (i.e., carbonization) temperature and the nature of the silica template. In general, higher CVD temperatures (>900 °C) generated high levels of graphitic character but compromised the mesostructural ordering of the carbon materials. The mesostructural ordering of the CNx materials (and replication of pore channel ordering from the silica template) depends on the nature of the mesoporous silica used as solid template. We achieved structural replication and high surface area (440−1000 m2/g) CNx materials from SBA-12, MCM-48, and SBA-15 silica templates. MCM-41 and HMS silicas did not function effectively as templates and generated low surface area (<320 m2/g) CNx materials. The particle morphology of the silica template was in all cases replicated in the carbon materials, and we observed hollow particles for samples prepared at CVD temperature of 1000 °C or higher.