Synthesis of mesoporous carbons using silica templates impregnated with mineral acids

• Mineral acid could be simply anchored on silica templates through ester bonding.
• The functionalized silicas showed moderate acidity for faithful carbon replication.
• The moderate acidity led to selective carbon formation inside the template pores.
• External carbon deposition was prevented despite using carbon precursor excessively.
• The present method could be extended for various mesoporous silica templates.

The pore walls of SBA-15, SBA-16 and KIT-6 mesoporous silica were acidified via the impregnation of phosphoric acid or sulfuric acid prior to their use as a template for mesoporous carbon synthesis with furfuryl alcohol. The effect of acid functionalization on carbon synthesis was investigated using X-ray powder diffraction, N2 adsorption, transmission electron microscopy, and solid-state 13C and 31P NMR spectroscopy. The results indicated that a significant portion of the impregnated mineral acid formed an ester with the surface silanol group. Therefore, the impregnated acid could lead to the selective formation of carbon frameworks inside the template pores, preventing external carbon deposition even when furfuryl alcohol was used excessively. The mineral acid impregnation yielded highly faithful carbon replicas of the mesoporous silica.

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