Ionic-liquid/metal-organic-framework composites: Synthesis and emerging sustainable applications

Ionic liquids (ILs) as emerging solvents have demonstrated a significant prospective in green chemistry, which can be used as green solvent, high efficiency catalyst, electrolyte, and so on. Metal–organic frameworks (MOFs), also called coordination polymers, are crystalline solids comprising of metal ions and organic linkers through coordination bonds, which are characterized by high porosity. Both ILs and MOFs have been extensively investigated by many groups all over the world, and their applications cover a wide range of fields, including but not limited to separations, catalysis to energy devices. IL/MOF composites, integrating the advantages of ILs and MOFs in one moiety, are a new class of functional materials, which have attracted increasing attention during the past decades. This paper offers an extensive overview on the design, synthesis and sustainable applications of IL/MOF composites and provides some critical viewpoints on the present challenges and future development directions. Firstly, we briefly introduced the background of ILs, MOFs, and the combination of ILs and MOFs. Afterwards, a system discussion on design and synthetic methodology for preparing IL/MOF composite. For each method, the basic chemical or operation principle and benefits/drawbacks are elaborated. Later, an overview on the sustainable applications of IL/MOF composites is provided by highlighting numerous recent representative literatures, covering carbon capture and conversion, chemical catalysis, adsorptive removal of pollutants, and acting as electrolytes and membranes in energy storage devices. Finally, research trends and insights into IL/MOF composites are outlined to extend the family of IL/MOF composites as well as their application scope. This paper is ended with challenges and future opportunities in this emerging area.