Garcia-Bordejé Enrique, Benito A M, Maser W K
Instituto de Carboquímica (ICB-CSIC), Miguel Luesma Castán 4, E-50018 Zaragoza, Spain.
Instituto de Carboquímica (ICB-CSIC), Miguel Luesma Castán 4, E-50018 Zaragoza, Spain.
Adv Colloid Interface Sci. 2021 Jun;292:102420. doi: 10.1016/j.cis.2021.102420. Epub 2021 Apr 15.
Recently, 3D graphene aerogel has garnered a high interest aiming at benefiting of the excellent properties of graphene in devices for energy storage or environmental remediation. Hydrothermal gelation of GO dispersion is a straightforward method that offers many opportunities for tuning its properties and for processing it to devices. By adjusting hydrothermal gelation and drying conditions, it is possible to tune the density (from ~3 mg cm to ~2 g cm), pore volume, pores size (micro to macropores), pore distribution, surface chemical polarity (hydrophobic or hydrophilic), and electrical conductivity (from ~0.5 S m to S cm). Besides other well explored applications in energy storage or environmental remediation, graphene aerogels have excellent prospects as support for catalysis since they combine the advantages of graphene sheets (high surface area, high electrical conductivity, surface chemistry tunability, high adsorption capacity…) while circumventing their drawbacks such as difficult separation from reaction media or tendency to stacking. Compared to other 3D porous carbon materials used as catalyst support, graphene aerogels have unique porous structure. The pore walls are the thinnest to be expected for a carbon material (the thickness of monolayer graphene is 0.335 nm), hence leading to the highest exposed surface area per weight and even per volume for compacted aerogels. This has the potential to maximize the catalytic site density per reactor mass and volume while minimizing the pressure drop for continuous reactions in flow. Herein, different strategies to control the porous texture, chemical and physical properties are revised along with their processability and scalability for the implementation into different morphologies and devices. Finally, the application of graphene aerogels in the catalysis field are overviewed, giving a perspective about future directions needing further research.
最近，3D石墨烯气凝胶因其在储能或环境修复设备中利用石墨烯的优异性能而备受关注。氧化石墨烯分散体的水热凝胶化是一种直接的方法，为调节其性能以及将其加工成器件提供了许多机会。通过调整水热凝胶化和干燥条件，可以调节密度（从3 mg/cm³到2 g/cm³）、孔体积、孔径（从微孔到宏孔）、孔分布、表面化学极性（疏水或亲水）以及电导率（从~0.5 S/m到S/cm）。除了在储能或环境修复方面的其他深入研究的应用外，石墨烯气凝胶作为催化载体具有出色的前景，因为它们结合了石墨烯片的优点（高表面积、高电导率、表面化学可调性、高吸附容量……），同时规避了它们的缺点，如难以从反应介质中分离或易于堆叠。与用作催化剂载体的其他3D多孔碳材料相比，石墨烯气凝胶具有独特的多孔结构。对于碳材料而言，孔壁是预期中最薄的（单层石墨烯的厚度为0.335 nm），因此对于压实的气凝胶，每重量甚至每体积的暴露表面积最高。这有可能使每个反应器质量和体积的催化位点密度最大化，同时使连续流动反应的压降最小化。在此，我们回顾了控制多孔结构、化学和物理性质的不同策略，以及它们在加工成不同形态和器件时的可加工性和可扩展性。最后，概述了石墨烯气凝胶在催化领域的应用，并对需要进一步研究的未来方向给出了展望。
