Recent advances in metal organic framework and cellulose nanomaterial composites

Metal organic frameworks (MOFs) have been widely used in various emerging fields due to their attractive characteristics, such as large specific surface area, highly porous structure, tunable porosity and pore size, versatile surface chemistry, diverse topological structure, and high chemical and thermal stability. However, nanoscale MOFs are prone to agglomeration, and their inherently crystalline structure leads to poor flexibility, processability and recyclability, which seriously limit the performance and application of MOFs. To address these deficiencies, MOFs have been composited with other materials through different strategies. One such attractive material is cellulose nanomaterials (CNMs), the most abundant and sustainable biomass on the earth. Herein, recent advances in the MOF/CNM composites in terms of preparation approaches, general properties, and emerging applications are overviewed, aiming to provide some useful guidance to researchers on the rational design of high-performance MOF/CNM composites in different forms for advanced applications in the future. Particularly, MOFs and CNMs are usually compounded in aqueous solutions through two main strategies, i.e., in-situ synthesis and ex-situ blending. Further processing of as-prepared MOF/CNM aqueous mixtures can generate MOF/CNM composites in four forms, i.e., hydrogel, powder, membrane and aerogel. Benefitted from advantages of both MOFs and CNMs, MOF/CNM composites hold exceptional high specific surface area, hierarchically porous structure, as well as superior electrochemical, mechanical and antibacterial properties, which can be further modulated and enhanced through optimizing type and composition of MOFs and CNMs, preparation method, and addition of other functional components. These exceptional properties offer huge potential in a wide range of application fields.