Muhoza Sixbert P, Cottam Matthew A, Gross Michael D
Department of Chemistry, Wake Forest University.
Department of Chemistry, Wake Forest University; Center for Energy, Environment, and Sustainability, Wake Forest University;
J Vis Exp. 2017 Apr 16(122):55500. doi: 10.3791/55500.
We demonstrate a method for the high temperature fabrication of porous, nanostructured yttria-stabilized-zirconia (YSZ, 8 mol% yttria - 92 mol% zirconia) scaffolds with tunable specific surface areas up to 80 m·g. An aqueous solution of a zirconium salt, yttrium salt, and glucose is mixed with propylene oxide (PO) to form a gel. The gel is dried under ambient conditions to form a xerogel. The xerogel is pressed into pellets and then sintered in an argon atmosphere. During sintering, a YSZ ceramic phase forms and the organic components decompose, leaving behind amorphous carbon. The carbon formed in situ serves as a hard template, preserving a high surface area YSZ nanomorphology at sintering temperature. The carbon is subsequently removed by oxidation in air at low temperature, resulting in a porous, nanostructured YSZ scaffold. The concentration of the carbon template and the final scaffold surface area can be systematically tuned by varying the glucose concentration in the gel synthesis. The carbon template concentration was quantified using thermogravimetric analysis (TGA), the surface area and pore size distribution was determined by physical adsorption measurements, and the morphology was characterized using scanning electron microscopy (SEM). Phase purity and crystallite size was determined using X-ray diffraction (XRD). This fabrication approach provides a novel, flexible platform for realizing unprecedented scaffold surface areas and nanomorphologies for ceramic-based electrochemical energy conversion applications, e.g. solid oxide fuel cell (SOFC) electrodes.
我们展示了一种高温制备多孔纳米结构氧化钇稳定氧化锆（YSZ，8摩尔%氧化钇 - 92摩尔%氧化锆）支架的方法，该支架的比表面积可调，最高可达80 m²·g⁻¹。将锆盐、钇盐和葡萄糖的水溶液与环氧丙烷（PO）混合形成凝胶。该凝胶在环境条件下干燥形成干凝胶。将干凝胶压制成颗粒，然后在氩气气氛中烧结。在烧结过程中，形成YSZ陶瓷相，有机成分分解，留下无定形碳。原位形成的碳作为硬模板，在烧结温度下保留高比表面积的YSZ纳米形态。随后通过在低温空气中氧化去除碳，得到多孔纳米结构的YSZ支架。通过改变凝胶合成中葡萄糖的浓度，可以系统地调节碳模板的浓度和最终支架的表面积。使用热重分析（TGA）对碳模板浓度进行定量，通过物理吸附测量确定表面积和孔径分布，并使用扫描电子显微镜（SEM）对形态进行表征。使用X射线衍射（XRD）确定相纯度和微晶尺寸。这种制备方法为实现用于陶瓷基电化学能量转换应用（如固体氧化物燃料电池（SOFC）电极）的前所未有的支架表面积和纳米形态提供了一个新颖、灵活的平台。
