热致变色型VO2-空心SiO2涂层制备研究及其作为“智能窗”的性能探究

Vanadium dioxide (VO2) coating, a smart temperature-control material, could be widely applied in “smart window” filed. It could intelligently control the indoor temperature, by responding to environmental temperature change, thus playing an important role in energy saving and environment protection. The VO2 coating is a potential material for smart window in the future building. The nature of this special performance is the phase transition of the pure monoclinic (M) VO2. The different valence states of vanadium and varies crystalline phase of VO2 even emphasized the difficulty in fabricating pure VO2 coating. Keeping the vanadium at +4 valence state during preparation process can solve this problem effectively. Besides, the relatively low visible transmission will influence the daylighting of VO2 coating. Hence, in this project, we plan to employ a facile, controllable and economic solution method to fabricate VO2(M) coating from the home-made stable ammonium citrato-oxovanadate(IV) as a source material. Then, we will fabricate the VO2(M)-hollow SiO2 composite coating by incorporating hollow SiO2 into the VO2 coating with 2 methods. And the optical property of the composite coating could be improved because of the combined effect between the SiO2 with low refractive index and hollow structure. Also we will reveal the influence rule of the hollow SiO2 on the optical property of the composite coating. Therefore, this work can promote the extensive application of VO2 based smart window. Finally, the different methods will be comparative analysis, which could also provide guidance for the optimization on the preparation technology of VO2-based thermochromic coating.

二氧化钒（VO2）涂层，一种智能温控材料，可广泛应用于智能窗领域。其可通过响应环境温度变化，智能调控室内温度，起到节能环保的作用，在未来建筑领域具有潜在应用价值。这一特殊性能的本质是纯单斜相(M)VO2的相转变。而钒的多价态和VO2的多晶型都使纯VO2(M)涂层的制备有很大难度。在制备过程中维持V的+4价可以有效解决这一问题。此外，VO2(M)涂层本身相对低的可见光透过率会影响实际应用采光。基于上述分析，本项目拟以自制的稳定柠檬酸氧钒（Ⅳ）铵为钒源料，其经过简单退火可转变为VO2(M)。再尝试采用不同方法引入SiO2空心球，利用低折射率SiO2和空心结构的共同作用，获取光学性能显著提高的VO2(M)-空心SiO2复合涂层，并揭示SiO2空心球对复合涂层光学性能的影响规律，为基于VO2的智能窗广泛应用提供借鉴。最后本研究将对不同制备方法进行比较分析，可这为优化VO2基涂层的制备工艺提供指导。

二氧化钒（VO2）是一种很有前景的智能热控材料，可作为节能智能涂料广泛应用于建筑和汽车领域。为优化VO2的综合性能和制备工艺，本项目将热致变色型VO2和低折射率SiO2相结合，通过比较不同的VO2(M)-空心SiO2复合涂层溶液法制备工艺，探索了单层纯VO2涂层结构与其热致变色性能和光学性能的关联，空心SiO2粒子对复合涂层热致变色性能和光学性能的影响规律，获得了解决涂层采光问题的可行方法。研究表明，在柠檬酸氧钒（Ⅳ）铵（CA-V（Ⅳ））溶液中加入分散剂十六烷基三甲基溴化铵（CTAB）可有效改善VO2涂层结构。当CTAB和V的摩尔比为0.10时，由于涂层的高纯度、高空隙率和均匀分散的小尺寸颗粒，VO2涂层的可见光区透光率（Tvis）高达70.6%，同时太阳能调控能力（ΔTsol）提高至13.4%。SiO2粒子的引入可使复合涂层的Tvis和ΔTsol较纯VO2涂层分别提升46.4%和52.1%。此外，分别从空心SiO2结构，提拉速度，硅钒摩尔比等方面详细研究了一步沉积法和分步沉积法制备复合涂层的工艺及其性能差异。对比发现，一步沉积法的实验工艺和产物性能均优于分步沉积法。空心SiO2粒子的引入可令复合涂层的Tvis提高到74.5%，且VO2(M)-空心SiO2复合涂层具有优异的隔热效果。使用该复合涂层玻璃与使用空白玻璃和VO2涂层玻璃的室内温差分别达24oC和6oC。另外，采用溶液沉淀法获得了H-SiO2-VO2(M)核壳结构纳米粒子。发现随着钒硅摩尔比增大，VO2外壳尺寸逐渐增大，颗粒结晶度增大，相变温度会提高。本项目研究对推进VO2基智能隔热材料的实际应用具有重要的指导意义。