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

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 m²·g^-1) and 86.4% (from 0.560 to 1.044 cm³·g^-1), respectively after the SiC-DC was activated at 950℃ for 2 h, mainly as a result of the increased micropore volume.