Effect of the CO2 activation parameters on the pore structure of silicon carbide-derived carbons

Abstract

A silicon carbide derived carbon (SiC-DC) with a high specific surface area (SSA) fabricated by chlorination of a silicon carbide derived from polysiloxane was activated by CO2. The effect of activation temperature and time on the microstructure of the activated samples was investigated by N2 sorption, XRD, SEM and TEM. Results showed that CO2 activation effectively changed the pore structure of the SiC-DC and had little impact on carbon crystallinity. The activated samples retained the morphology of the SiC powder or the non-activated SiC-DC. The SSA, total pore volume (Vtot) and micropore volume of the activated SiC-DCs all increased and the yield decreased with increasing activation temperature or time. The SSA and Vtot increased by 46.5 % (from 1 316.8 to 1 929.0 m2g−1) and 86.4 % (from 0.560 to 1.044 cm3g−1), respectively after the SiC-DC was activated at 950 °C for 2 h, mainly as a result of the increased micropore volume.