Catalonia Institute for Energy Research-IREC , 08930 Sant Adrià de Besòs, Barcelona , Spain.
LENS-MIND, Departament d'Enginyeria Electrònica I Biomèdica , Universitat de Barcelona , 08028 Barcelona , Spain.
ACS Appl Mater Interfaces. 2018 May 9;10(18):16041-16048. doi: 10.1021/acsami.8b03754. Epub 2018 Apr 25.
We present a novel method to produce crystalline oxide aerogels which is based on the cross-linking of preformed colloidal nanocrystals (NCs) triggered by propylene oxide (PO). Ceria and titania were used to illustrate this new approach. Ceria and titania colloidal NCs with tuned geometry and crystal facets were produced in solution from the decomposition of a suitable salt in the presence of oleylamine (OAm). The native surface ligands were replaced by amino acids, rendering the NCs colloidally stable in polar solvents. The NC colloidal solution was then gelled by adding PO, which gradually stripped the ligands from the NC surface, triggering a slow NC aggregation. NC-based metal oxide aerogels displayed both high surface areas and excellent crystallinity associated with the crystalline nature of the constituent building blocks, even without any annealing step. Such NC-based metal oxide aerogels showed higher thermal stability compared with aerogels directly produced from ionic precursors using conventional sol-gel chemistry strategies.
我们提出了一种生产晶态氧化物气凝胶的新方法，该方法基于通过环氧丙烷（PO）交联预先形成的胶体纳米晶（NC）。我们使用氧化铈和二氧化钛来说明这种新方法。通过在油酸胺（OAm）存在下分解合适的盐，在溶液中制备了具有可调几何形状和晶面的氧化铈和二氧化钛胶体 NC。NC 表面的天然配体被氨基酸取代，使 NC 在极性溶剂中稳定存在。然后通过添加 PO 将 NC 胶体溶液凝胶化，这逐渐从 NC 表面剥离配体，引发 NC 的缓慢聚集。基于 NC 的金属氧化物气凝胶显示出高比表面积和优异的结晶度，这与组成构建块的结晶性质有关，甚至无需任何退火步骤。与使用传统溶胶-凝胶化学策略直接从离子前体制备的气凝胶相比，基于 NC 的金属氧化物气凝胶具有更高的热稳定性。
