Department of Chemistry, University of Fribourg, Chemin du Musée 9, 1700 Fribourg, Switzerland.
ACS Appl Mater Interfaces. 2023 May 3;15(17):21394-21402. doi: 10.1021/acsami.3c03424. Epub 2023 Apr 20.
Conventional synthetic strategies do not allow one to impart structural anisotropy into porous carbons, thus leading to limited control over their textural properties. While structural anisotropy alters the mechanical properties of materials, it also introduces an additional degree of directionality to increase the pore connectivity and thus the flux in the designed direction. Accordingly, in this work the structure of porous carbons prepared from resorcinol-formaldehyde gels has been rendered anisotropic by integrating superparamagnetic colloids to the sol-gel precursor solution and by applying a uniform magnetic field during the sol-gel transition, which enables the self-assembly of magnetic colloids into chainlike structures to template the growth of the gel phase. Notably, the anisotropic pore structure is maintained upon pyrolysis of the gel, leading to hierarchically porous carbon monoliths with tunable structure and porosities. With an advantage granted to anisotropic materials, these porous carbons showed higher porosity, a higher CO uptake capacity of 3.45 mmol g at 273 K at 1.1 bar, and faster adsorption kinetics compared to the ones synthesized in the absence of magnetic field. Moreover, these materials were also used as magnetic sorbents with fast adsorption kinetics for efficient oil-spill cleanup and retrieved easily by using an external magnetic field.
传统的合成策略不允许将结构各向异性赋予多孔碳，从而导致对其结构性质的控制有限。虽然结构各向异性改变了材料的机械性能，但它也引入了额外的方向性，以增加孔的连通性，从而增加设计方向上的通量。因此，在这项工作中，通过将超顺磁胶体集成到溶胶-凝胶前体溶液中，并在溶胶-凝胶转变过程中施加均匀磁场，使由间苯二酚-甲醛凝胶制备的多孔碳的结构呈现各向异性，从而使磁性胶体自组装成链状结构，以模板凝胶相的生长。值得注意的是，在凝胶的热解过程中保持了各向异性的孔结构，从而得到了具有可调结构和孔隙率的分级多孔碳块体。各向异性材料具有优势，这些多孔碳表现出更高的孔隙率、更高的 CO 吸附量（在 273 K 和 1.1 bar 下为 3.45 mmol g）和更快的吸附动力学，与在没有磁场的情况下合成的多孔碳相比。此外，这些材料还被用作具有快速吸附动力学的磁性吸附剂，用于高效的溢油清理，并且可以很容易地通过使用外部磁场来回收。
