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

Abstract

Ionic liquids (ILs) as emerging solvents have demonstrated a significant promise for green chemistry application and can be used as green solvents, high-efficiency catalysts, electrolytes, and so on. Metal –organic frameworks (MOFs), also called coordination polymers, are crystalline solids comprising metal ions and organic linkers linked 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 separation, catalysis and energy devices. IL/MOF composites, integrating the advantages of ILs and MOFs in one moiety, are a new class of functional materials that have attracted increasing attention during the past decades. This study offers an extensive overview of 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 introduce the background of ILs, MOFs, and the combination of ILs and MOFs. Thereafter, we systematically discuss the design and methodology for the synthesis of IL/MOF composites. For each method, the basic chemical or operation principle and benefits/drawbacks are elaborated. Later, an overview of the sustainable applications of IL/MOF composites is provided by highlighting numerous recent representative studies reported in the literature, covering carbon capture and conversion, chemical catalysis, adsorptive removal of pollutants, and utilization 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 and their application scope.