Zheng Chunxue, Li Xinyang, Yu Jie, Huang Zhulin, Li Ming, Hu Xiaoye, Li Yue
Key Laboratory of Materials Physics and Anhui Key Laboratory of Nanomaterials and Nanotechnology, Institute of Solid State Physics, HFIPS, Chinese Academy of Sciences, Hefei, 230031, P. R. China.
University of Science and Technology of China, Hefei 230026, P. R. China.
Nanoscale. 2024 Feb 29;16(9):4600-4608. doi: 10.1039/d3nr06076d.
Silicon carbide (SiC) aerogels, which possess unique porous structure and high ablation resistance, show great potential as thermal insulation materials, but their wide application is limited by expensive and cumbersome synthetic procedures. Therefore, it is pivotal to develop a facile, versatile, and cost-effective method for producing SiC aerogels. Herein, we have successfully prepared ultra-light SiC nanowire aerogels (SNWAs) boasting remarkably low thermal conductivity, using biomass-derived carbon templates (BCTs) through a direct carbothermal reduction method. The BCTs obtained by simply carbonizing freeze-dried eggplants can serve not only as the carbon sources but also as the templates for the growth of SiC nanowires. The resultant three-dimensional (3D) SNWAs possess various porous structures, incorporating the original micro-sized pores inherited from the eggplant and nano-sized pores constructed from interconnected SiC nanowires. These multi-scale pore structures bestow SNWAs with lower gas-phase heat conduction characteristics. Besides, the numerous stacking faults and heterojunctions present in the SiC nanowires play a key role in obstructing the solid-phase heat transfer and reinforcing the SiC skeleton. As a result, the SNWAs show an exceptionally low thermal conductivity, measuring 0.0149 W m K at room temperature, and maintain this low value (0.0256 W m K) even at 500 °C. Remarkably, even after being exposed to air at 1200 °C for 2 h, the SNWAs maintain a low thermal conductivity of 0.0226 W m K. Such low-cost and effective preparation of biomass-derived SiC aerogels is anticipated to pave a new avenue for the development of advanced thermal insulators.
碳化硅（SiC）气凝胶具有独特的多孔结构和高抗烧蚀性，作为隔热材料具有巨大潜力，但其广泛应用受到昂贵且繁琐的合成工艺限制。因此，开发一种简便、通用且经济高效的制备SiC气凝胶的方法至关重要。在此，我们通过直接碳热还原法，利用生物质衍生碳模板（BCTs）成功制备了具有极低热导率的超轻SiC纳米线气凝胶（SNWAs）。通过简单碳化冻干茄子获得的BCTs不仅可作为碳源，还可作为SiC纳米线生长的模板。所得的三维（3D）SNWAs具有多种多孔结构，包含从茄子继承的原始微米级孔隙以及由相互连接的SiC纳米线构成的纳米级孔隙。这些多尺度孔隙结构赋予SNWAs较低的气相热传导特性。此外，SiC纳米线中存在的大量堆垛层错和异质结在阻碍固相热传递和增强SiC骨架方面起关键作用。结果，SNWAs表现出极低的热导率，室温下为0.0149 W m⁻¹ K⁻¹，即使在500°C时也保持这一低值（0.0256 W m⁻¹ K⁻¹）。值得注意的是，即使在1200°C空气中暴露2小时后，SNWAs仍保持0.0226 W m⁻¹ K⁻¹的低热导率。这种低成本且有效的生物质衍生SiC气凝胶制备方法有望为先进隔热材料的开发开辟一条新途径。
