Fabrication and characterization of robust glassy carbon monoliths via sol-gel process followed by direct ambient drying and carbonization

Glassy carbon monoliths (GCMs) are one of the most attractive carbon materials presently, while their applications are limited by their fussy fabrication processes and relatively poor mechanical properties. Herein, we report a facile fabrication method of high-strength crack-free GCMs using furfuryl alcohol via sol-gel process and direct drying at ambient conditions followed by carbonization. The in-situ volume shrinkage results reveal that volume shrinkage and mass loss show similar trends during the whole carbonization process and the percentage of volume shrinkage is always higher than that of mass loss, so that highly densified nonporous carbon monoliths instead of normally porous materials are acquired. Our results indicate that the kinetics of the sol formation plays a vital role in controlling the evolution process, mechanical properties, and microstructure of the carbon monoliths. By tuning the kinetics of the sol formation, GCMs of compressive strength ranging in 12.4–41.5 MPa can be prepared. HRTEM images show that nanoscale graphite dispersed in GCMs can be formed at a very low carbonization temperature, whose quantity and morphology are strongly affected by sol reaction time.

Graphical Abstract