金屬有機框架(metal-organic frameworks)等孔洞材料因其在氣體儲存、分離和催化等能源相關應用中的巨大潛力而引起了廣泛關注。 在金屬有機框架的各種特性中，其表面積對於評估該材料在這些應用(尤其是氣體儲存)中的能力至關重要。 Brunauer-Emmmett-Teller(BET)方法是測定多孔材料表面積的常用方法。 然而，近期文獻表示該方法會嚴重高估孔洞材料的表面積。為此開發替代方案來更準確地確定MOF的表面積仍然是此領域中的一個關鍵方向。在此研究中，通過系統地研究263種不同有機金屬框架的BET表面積，發現在等溫吸附曲線中的吸附量大幅上升與有機金屬框架之表面積高估相關。在選擇吸附量大幅上升後的吸附曲線所對應的線性區間來計算BET表面積，會使BET方法錯估材料的單層吸附量，從而導致高估表面積的情況。通過設置上限以避免BET方法選擇等溫吸附曲線中吸附量大幅上升後的線性區間，藉此來使BET方法能更準確地預測材料的表面積。;Porous materials such as metal-organic frameworks (MOFs) have drawn considerable attention owing to their great potential in energy-related applications such as gas storage, separations, and catalysis, etc. Among various properties of MOFs, their surface area is essential for evaluating their capability in those applications, especially gas storage. The Brunauer-Emmmett-Teller (BET) method is a commonly adopted approach to determining the surface area of porous materials. However, the method has been reported to result in largely overestimated surface areas. To this end, developing alternatives to more accurately determine the surface area of MOFs remains a critical direction in the community. In this study, through systematically studying the BET surface areas of 263 diverse MOFs, a large loading jump in the adsorption uptake is found to correlate with the overestimation in the area prediction for MOFs, by selecting a linear region that is after the loading gap to calculate the BET surface area can lead to an overestimation of the monolayer capacity and, consequently, an overestimation of the surface area. To improve the accuracy of the BET method, an upper limit can be set to avoid selecting the linear region after the significant uptake of adsorption in the adsorption isotherm. By setting this upper limit, the accuracy of BET method can be enhanced.
