氧化石墨烯掺杂二氧化硅气凝胶的特性研究

Characteristics of graphene oxide doped silica aerogels

为满足高温防护需求,快速制备高强度、低导热系数的气凝胶成为一项重要的科学挑战。采用超临界干燥法,成功通过掺杂氧化石墨烯(GO)的方式,改善了二氧化硅气凝胶的性能。通过电子显微镜观察发现,GO均匀地镶嵌在气凝胶基体中,形成了有效的支撑骨架,显著增强了气凝胶的强度。傅立叶变换红外光谱分析表明,GO与二氧化硅气凝胶之间仅存在物理结合,并未形成明显的化学键。通过氮吸附/解吸测量发现,GO/SiO_(2)气凝胶的比表面积和孔径可以通过调整GO的用量进行可控调节。实验结果显示,当GO含量为质量分数0.5%,1%和2%时,GO/SiO_(2)气凝胶的比表面积分别为895,1294和997 m^(2)/g,与未掺杂的SiO_(2)气凝胶(852 m^(2)/g)相比有所增加。由于GO的加入,GO/SiO_(2)气凝胶的密度(0.07 g/cm^(3))略高于纯SiO_(2)气凝胶(0.06 g/cm^(3)),为其提供了更高的强度和承载能力。此外,GO/SiO_(2)气凝胶的导热系数为0.0176~0.0204 W/(m·K),低于纯SiO_(2)气凝胶(0.0221 W/(m·K))。该研究为SiO_(2)气凝胶在实际应用中的推广和应用提供了新思路。

In order to meet the needs of high temperature protection,rapid preparation of aerogels with high strength and low thermal conductivity has become an important scientific challenge.The performance of silica aerogels prepared by supercritical drying method was successfully improved by doping graphene oxide(GO).It was observed by electron microscope that GO was evenly embedded in the gel matrix,forming an effective support framework,and significantly enhancing the strength of the gel.Fourier transform infrared spectroscopy analysis showed that there was only physical binding between GO and silica aerogel,and no obvious chemical bond was formed.The nitrogen adsorption/desorption measurements show that the specific area and pore size of GO/SiO_(2)aerogels can be controlable by adjusting the GO amount.When the content of GO is 0.5%,1%and 2%by mass,the specific surface areas of GO/SiO_(2)aerogels are 895 m^(2)/g,1294 m^(2)/g and 997 m^(2)/g,respectively,which is higher than that of undoped silica aerogels(852 m^(2)/g).Due to the addition of GO,the density of GO/SiO_(2)aerogel(0.07 g/cm^(3))is slightly higher than that of pure SiO_(2)aerogel(0.06 g/cm^(3)),providing it with higher strength and bearing capacity.In addition,the thermal conductivity of these doped aerogels is 0.0176-0.0204 W/(m·K),which is lower than that of pure SiO_(2)aerogels(0.0221 W/(m·K)).This result provides a new idea and method for the promotion and application of SiO_(2)aerogel in practical applications.