DMF及热处理对常压制备Cu掺杂SiO2纳米复合气凝胶的影响

以正硅酸乙酯(TEOS)为硅源, 硝酸铜(Cu(NO3)2·3H2O)为铜源, 通过在复合溶胶体系中引入干燥控制化学添加剂(DCCA)N,N-二甲基甲酰胺(DMF)进行原位共溶胶-凝胶, 结合常压干燥工艺, 制备出具有高比表面积(560 m2·g-1)的Cu-SiO2纳米复合气凝胶(含铜质量分数为5%). 研究了DMF对凝胶时间、干燥过程和复合气凝胶形态结构的影响, 利用N2物理吸附, 全自动X射线衍射(XRD)仪, 傅立叶变换红外(FT-IR)光谱仪, 透射电子显微镜(TEM)等对样品的形貌结构进行了表征. 实验结果表明, DMF能有效防止凝胶的开裂, 抑制颗粒团簇的产生, 使所得复合气凝胶的粒径减小, 比表面积增加, 微观结构更趋完善. 高温热处理后, Cu-SiO2中的铜物种仍高度分散于骨架网络中, 复合气凝胶显示出良好的热稳定性.

Effect of DMF and Heat Treatment on the Copper-Doped Silica Nanocomposite Aerogel Prepared by Ambient Drying

Using tetraethyl orthosilicate (TEOS) as silicon precursor and copper nitrate (Cu(NO3)2·3H2O) as copper source, a copper-doped silica nanocomposite aerogel with a high specific surface area (560 m2·g-1) and 5% (mass fraction) of Cu content was prepared via an in-situ sol-gel process and ambient drying by introduction of a drying control chemical additive (DCCA) N,N-dimethylformamide (DMF) to the composite sol systems. The effect of DMF on gel time, drying process, the morphology and the structure of the composite aerogel was discussed. Structure and morphology of samples were characterized by N2 physical adsorption, X-ray diffractometer (XRD), Fourier transform infrared (FT-IR) spectrometer and transmission electron microscope (TEM). Results showed that DMF was effective in preventing gel cracking and inhibiting the formation particle clusters. The diameter of composite aerogel decreased as specific surface area increased and the microstructure became more optimal. After high temperature treatment, copper species in Cu-SiO2 were still highly dispersed, which indicated good thermal stability of the composite aerogel.