弹性 SiO₂气凝胶由于其独特的纳米结构、优异的吸附、隔热、力学性能受到了国内外研究者的广泛关注。目前报道的弹性 SiO₂气凝胶通常需经超临界干燥法制备，其设备昂贵、能耗较高，不利于大规模推广应用。本论文提出以静电纺丝SiO₂纳米纤维为增韧材料，设计制备一种新兴的弹性SiO₂纳米纤维气凝胶（SiO₂ Nanofibers Aerogel，SiO₂ NFAG），通过改变 SiO₂纤维的添加量，调节 SiO₂ NFAG 的微观结构与尺寸，获得吸油、力学和隔热性能优异的弹性SiO₂ NFAG。在此基础上，制备基于弹性SiO₂ NFAG 光热蒸发结构，研究其光热蒸发海水淡化性能。主要的研究内容和成果如下：

（1）采用常压干燥法，设计制备了一种新兴的SiO₂纳米纤维增强的弹性SiO₂ NFAG。结果表明，SiO₂纳米纤维的引入，使弹性SiO₂气凝胶的网络结构由球形颗粒转变为核壳纤维结构，纤维之间通过复合硅烷牢牢粘结，纤维的直径随着SiO₂纤维的增加而减小，SiO₂ NFAG具有丰富的大孔结构。

（2）研究了 SiO₂ NFAG 的吸油、力学与隔热性能。结果表明，SiO₂ NFAG 水接触角可达 154.1°，具有良好的疏水性，可快速吸油，对 CH₂Cl₂ 的吸附能力最优，吸附倍率为 10.33 g g-1，随着 SiO₂ 纤维含量的增加，其吸附性能降低，但 SiO₂ NFAG 具有稳定的循环吸附性能，可快速压缩回弹。随着 SiO₂ 纳米纤维的增加，气凝胶的强度逐渐增加，当含量为 8 mg·mL^-1 时的杨氏模量为 0.91 MPa，SiO₂ NFAG 隔热性能随着纤维含量增加而略有提升，有望应用于保冷和隔热领域。

（3）以弹性 SiO₂ NFAG 为隔热层构建了两种光热蒸发结构。结果表明，在 1 单位光强下，SiO₂ NFAG-炭黑/聚丙烯腈纤维膜（SiO₂ NFAG-CB/PAN）柱体蒸发结构和SiO₂ NFAG-碳管（SiO₂ NFAG-CNT）双亲结构的水蒸发速率分别为 2.29 kg m^-2 h^-1 和2.934 kg m^-2 h^-1，光热转化效率为分别为 86.53%和 87.97%，并表现出一定的抗盐性，二者均具有优异的光热蒸发性能。

关 键 词：SiO₂弹性气凝胶；SiO₂纳米纤维；溶胶-凝胶；常压干燥；光热蒸发

研究类型：基础研究

Elastic SiO₂ aerogels have attracted extensive attention from researchers at home and abroad due to their unique nanostructure, excellent adsorption, thermal insulation, and mechanical properties. The currently reported elastic SiO₂ aerogels are usually dried by supercritical drying method. However, the expensive equipment and high energy consumption are not favorable for large-scale production and application, which limits their application. This thesis proposes to design and fabricate a new elastic SiO₂ Nanofibers aerogel (SiO₂ nanofibers aerogel, SiO₂ NFAG) by using electrospinning SiO₂ nanofibers as toughening materials. The micro-morphology and size were adjusted by changing the quantity of SiO₂ nanofibers. Elastic SiO₂ NFAG with excellent oil absorption, mechanical and thermal insulation properties were obtained. On this basis, a photothermal evaporation structure based on elastic SiO₂ NFAG was prepared, and its photothermal evaporation seawater desalination performance was studied. The main research contents and results are as follows：

(1) A new SiO₂ nanofiber reinforced elastic SiO₂ NFAG was designed and fabricated by atmospheric drying method. The results show that the introduction of SiO₂ nanofibers changes the network structure of elastic SiO₂ aerogel from spherical particles to core-shell fiber structure. The fibers are firmly bonded by composite silane, and the diameter of the fibers decreases with the increase of the amount of SiO₂ fibers. SiO₂ NFAG has abundant macroporous structure.

(2) The oil absorption, mechanical and thermal insulation properties of SiO₂ NFAG were studied. The results show that SiO₂ NFAG has good hydrophobicity with water contact angle of 154.1°. SiO₂ NFAG can absorb oil quickly, and has the best adsorption capacity for CH₂Cl₂ of 10.33 g g-1 . With the increase of SiO₂ fiber content, the adsorption capacity decreases. But SiO₂ NFAG has stable cyclic adsorption performance because of its fast compression and rebound ability. The strength of the aerogel gradually increases with the increase of the SiO₂ nanofibers addition. The Young's modulus is 0.91 MPa with addition of 8 mg·mL^-1 . The thermal insulation performance of SiO₂ NFAG increases with the increase lightly of fiber content, which is expected to be applied for cold. and thermal insulation field.

(3) Two photothermal evaporation structures were constructed with elastic SiO₂ NFAG as the thermal insulation layer. The results show that the evaporation rate of SiO₂ NFAG carbon black/polyacrylonitrile fiber membrane (SiO₂ NFAG-CB/PAN) cylinder and SiO₂ NFAG-Carbon nanotube (SiO₂ NFAG-CNT) amphiphilic structure can reach up to 2.29 kg m^-2 h^-1 and 2.29 kg m^-2 h^-1 , respectively under 1 light intensity. The related photothermal conversion efficiency of SiO₂ NFAG-CB/PAN cylinder and SiO₂ NFAG-CNT amphiphilic structure are 86.53% and 87.97% respecticely. Both the two structures display excellent photothermal evaporation performance.

Key words：SiO₂ aerogel; SiO₂ nanofibers; Sol-gel; Atmospheric drying; Photothermal evaporation

Thesis：Foundamental Research

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