An Emerging Family of Hybrid Nanomaterials: Metal-Organic Framework/Aerogel Composites

Metal-organic frameworks (MOFs) are crystalline nanoporous coordination polymers made of metal ions and organic linkers. Aerogels are highly nanoporous amorphous polymers that can be organic, inorganic, or hybrid. Both of these unique materials have been extensively investigated in many laboratories around the world for a wide range of applications ranging from separations to catalysis, resulting in thousands of published articles in a wide variety of journals. MOF/aerogel composites (MOFACs) are a new class of nanostructured materials that are attracting increasing attention because of their favorable properties. The combination of the micro- and mesoporosities of MOFs with the meso- and macroporosities of aerogels makes MOFACs hierarchically multimodal porous materials. With their high surface areas and combined morphological, mechanical, physicochemical, and functional properties of both MOFs and aerogels, MOFACs have demonstrated outstanding performances in various applications. Herein we provide an overview of the techniques used to synthesize MOFACs in various shapes such as monoliths or particles based on incorporation of MOFs into the porous networks of aerogels along with literature examples. The synthesis of aerogel-supported metals and metal oxides using MOFACs as precursors is also described. Several applications of these composites are reviewed, including adsorption, separation, catalysis, energy conversion, and storage devices such as batteries and supercapacitors. Future prospects in synthesis techniques and applications are provided to address opportunities and challenges in the field of MOFACs.