Bifunctionalized hybrid silica aerogels for stable low-concentration CO₂ capture and thermal insulation under humid and high-temperature conditions

To produce a multifunctional silica aerogel with excellent stability under humid and high-temperature conditions, bifunctionalized hybrid silica aerogels (BHSAs) were created by a simple and eco-friendly self-catalyzed sol-gel process. BHSA can be used for thermal insulation and CO₂ capture with high durability with two functional groups including methyl and amine hybridized. The highest specific surface area (343 m²/g), pore volume (1.66 cm³/g), and surface amine content (2.14 mmol/g) were attained by TMA262 with an appropriate tetraethoxysilane (TEOS)/methyltriethoxysilane (MTES) molar ratio, as well as a water contact angle of 143°. TMA262 demonstrated high CO₂ adsorption capacity (1.87 mmol/g) and kinetics in humid 1% CO₂. With a low thermal conductivity at 25 °C (0.019 W/(m·K)), TMA262 exhibited outstanding thermal insulation over the temperature range stretching from −100 to 1300 °C. Accelerated aging and thermal treatment indicated that TMA262 possessed excellent long-term stability for CO₂ capture and thermal insulation under humid and high-temperature conditions, and water played a significant role in CO₂ adsorption capacity. This study seamlessly integrates a diverse array of functionalities within the silica aerogel, offering significant guidance for the advancement of aerogels tailored for multi-scenario applications under extreme conditions.