Taheri Poroshat, Lang John C, Kenvin Jeffrey, Kroll Peter
Department of Chemistry & Biochemistry, The University of Texas at Arlington, Arlington, TX 76019, USA.
Micromeritics Instrument Corporation, 4356 Communications Drive, Norcross, Georgia 30093, USA.
Phys Chem Chem Phys. 2021 Mar 11;23(9):5422-5430. doi: 10.1039/d0cp05520d.
We perform Differential Hysteresis Scanning (DHS) Porosimetry of amorphous silicon oxycarbide aerogels to quantify hierarchical connectivity in these porous materials. We contrast high-resolution argon sorption scanning isotherms of samples obtained through a non-templated synthesis using different solvents, and characterize respective changes after calcination at 1000 °C. The multi-scan DHS data sets are analyzed through non-negative least-squares deconvolution using a kernel of theoretically derived isotherms for a selection of hierarchical geometries using non-local density functional theory (NL-DFT). We obtain two-dimensional contour plots that characterize mesopores according to the ratio between pore diameter and its connecting window. Combined information from DHS and complementary BET and BJH approaches reveals one system with monomodal distribution both in pore diameters and in window diameters. Hence, this amorphous material exhibits a uniformity usually only observed for crystalline systems. We demonstrate that DHS analysis provides quantitative data analyzing the hierarchical structure of mesoporous materials and unlocks pathways towards tailored materials with control of surface heterogeneity, localization, and sequential accessibility - even for amorphous systems.
我们对非晶态碳氧化硅气凝胶进行差示滞后扫描（DHS）孔隙率测定，以量化这些多孔材料中的分级连通性。我们对比了通过使用不同溶剂的非模板合成获得的样品的高分辨率氩吸附扫描等温线，并表征了在1000°C煅烧后的各自变化。通过非负最小二乘去卷积分析多扫描DHS数据集，使用基于非局部密度泛函理论（NL-DFT）的理论推导等温线核，针对一系列分级几何结构进行分析。我们获得了二维等高线图，根据孔径与其连接窗口之间的比率来表征中孔。来自DHS以及互补的BET和BJH方法的综合信息揭示了一个在孔径和窗口直径方面均具有单峰分布的系统。因此，这种非晶态材料展现出一种通常仅在晶体系统中观察到的均匀性。我们证明，DHS分析提供了用于分析介孔材料分级结构的定量数据，并为制备具有可控表面不均匀性、定位和顺序可及性的定制材料开辟了途径——即使对于非晶态系统也是如此。
