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A new approach for forming aerogels with various silicon-based compositions and hybrids between ceramics and carbon has been developed by combining efficient hydrosilylation as the hybridizationcrosslinking approach associated with gelation in the presence of solvent and followed by supercritical drying techniques. Highly porous carbon-enriched SiC/C aerogels with adequate mechanical durability have been synthesized, pyrolyzed, and characterized. The "wet" gels were obtained by crosslinking a commercial polycarbosilane with divinylbenzene via Pt-catalyzed hydrosilylation reaction in highly diluted condition (90 vol% of solvent). A supercritical drying was performed after exchanging the solvent (cyclohexane) with liquid CO 2 forming undamaged aerogels. A subsequent pyrolysis and heat treatment (up to 1500°C) in argon flow converted the polymeric aerogel into a SiC/C-based material with bulk density of 166 kg m À3 , SSA of 444 m 2 g À1 , a micro-meso pore volume of 0.79 cm 3 g À1 , total porosity above 90 vol% and ultimate compressive strength of 1.6 MPa. The final product was compared to its cured gel and intermediates obtained during the pyrolysis process.

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Silicon was selectively removed from a silicon carbonitride (SiCN) aerogel by hot chlorine gas treatment, leading to a N-doped carbon aerogel (N-CDC aerogel) possessing high specific surface area and hierarchical pore structure.

A simple process for synthesizing SiOC foams with low density (45115 kg/m 3 ) and high porosity (9598%) is reported here. The process involves the impregnation of a flexible polyurethane foam with a preceramic polymer solution and pyrolysis in the inert atmosphere. SEM analysis showed that the resultant SiOC foam had a fully open interconnected porous structure with dense struts. N 2 adsorption test performed on the as-pyrolyzed SiOC foams showed very low surface area, which can be increased by leaching out the SiO 2 -rich network by HF, leaving behind a mesoporous C-rich SiOC foam. The remarkably high surface area up to 147 m 2 /g (7350 m 2 /liter) has been reached after 24 h etching. HF etching leads to a decrease of the compressive strength. However, a good combination of compressive strength (³80 kPa), porosity (95%) and surface area (7315 m 2 /liter) of the foam has been obtained and it makes the SiOC foam a potential candidate for specific applications.