Flexible and Porous Nanocellulose Aerogels with High Loadings of Metal–Organic‐Framework Particles for Separations Applications

Abstract

Keywords: metal-organic frameworks • cellulose nanocrystals • aerogels • water purification • porous materialsThis work overcomes the longstanding challenge of processing metal-organic framework (MOF) powders into a convenient and tailorable form by entrapping them within a cellulose nanocrystal (CNC) aerogel. MOFs are a new class of porous materials, assembled from metal ions or ion clusters bridged by organic ligands. Since the pioneering work on MOF-5 reported by Yaghi and co-workers, [1] MOFs have received great attention due to their large surface area and porosity, high thermal stability, and tunable pore structure. MOFs have shown great potential in various applications including gas separation [2] and storage, [3] chemical sensing, [4] catalysis, [5] and so on. Designing and preparing new MOFs, [6] post-modification of existing MOFs, [7] and fabrication of MOFs into different structures [8] are currently of great interest.However, due to the crystalline nature of MOFs, they are most commonly found in powder form and their processability and handling remain a significant challenge. [9] Integrating MOFs onto or within various substrates to produce a shapeable, cost-efficient, and chemically inert product is one way to expand the potential applications of these functional materials.The deposition and growth of MOF particles on substrates has become a highly researched area but is severely constrained by the physical and chemical requirements of the substrate and gives materials with limited functionality. [10] Usually surface modifications are needed in Submitted to 2 order to increase the compatibility between MOFs and substrates, and while different methods to grow MOFs exist, including solvothermal, [11] secondary, [12] layer by layer growth, [13] and electrochemical deposition, [14] the substrates have to be stable during the process or restricted synthetic conditions must be employed. [15] Incorporation of MOF particles onto polymer or fiber substrates (of both synthetic [16] and natural origin [17] ), by blending, deposition or in situ growth, has been demonstrated. However, while these approaches overcome some of the disadvantages of preparing MOF-only materials or planar MOF films, most examples reported to date are either limited by low MOF loadings or reduced flexibility. [16b, 18] One alternative approach used to avoid processing or depositing MOFs is to produce metal organic framework gels (MOGs) which are high surface area MOF-like materials but they generally lack the ordered crystal lattice and desired physical properties of MOFs.[19]Nanocellulose shows great promise for use as a supporting substrate [20] or templating material [21] , especially in the form of cellulose aerogels and foams, because of its high strength, light weight, low cost, non-toxicity and its ability to be processed easily in water. [22] Cellulose nanocrystals (CNCs), cellulose nanofibrils (CNFs), and bacterial cellulose are the most common types of nanocellulose which are now being produced with con...

Ultrarobust Biochips with Metal–Organic Framework Coating for Point-of-Care Diagnosis

“…Metal-organic frameworks (MOFs), comprised of metal ions or clusters linked by organic ligands, 24–25 have shown promising applications in gas and energy storage, 26–27 drug delivery, 28 catalysis, 29–30 separation, 31–32 and chemical sensors. 33 Their attractive properties include large surface area, tunable porosity, organic functionality, stable shelf-life and excellent thermal stability.…”

Benchmarking Cellulose Nanocrystals: From the Laboratory to Industrial Production

“…6, [44][45][46][47][48][49][50] The surface modification routes we have developed are water-based and scalable leading to, for example, hydrophobic, responsive, biomimetic, and crosslinkable CNCs. [51][52][53][54][55] Although we have targeted advanced applications such as industrial coatings, 56,57 tissue scaffolds, 6,48,50 energy storage 2,58 water purification 59 and food and cosmetics, [44][45][46][47] we remain committed to thorough characterization of CNC particles and interfaces. This has included characterization of chemical, physical, mechanical and selfassembly properties, 34,52,[60][61][62] as well as the development of new methods to predict and assess CNC dispersion.…”

Flexible and Hierarchical Metal–Organic Framework Composites for High‐Performance Catalysis

“…[8] However, most MOFs are rigid, brittle, and very easy to be crumbled. [14] However, these methods are synthetically tedious and cannot retain the original crystalline morphology of MOFs.W ea im to develop stable MOF/foam composite materials by ao ne-pot procedure,w hich enables the direct preparation of high-quality composite materials.More importantly,this would provide ageneral strategy to prepare MOFs for practical applications,e specially in heterogeneous catalysis over as cope broader than ever before.Heterogeneous catalysts have many advantages over their homogeneous counterparts in reactor design, such as easy operation, excellent activity,g ood selectivity,a nd catalyst reusability.T oi mprove the catalytic performance of MOFs, ag reat variety of approaches have been explored, but it remains ad aunting challenge to create macropores in ac oordination network. [10] All of these disadvantages have largely limited their practical applications in various domains.T ot ackle this problem, tremendous efforts have been made to hybridize MOFs with other materials,thus realizing the combination of their advantages and circumventing shortcomings.Avariety of MOF composites have been successfully developed, such as MOF/graphene, [11a] MOF/graphite, [11b] MOF/carbon nanotubes, [11c] MOF/polymers, [11d] MOF/enzymes, [11e] and MOF/metal nanoparticles, [11f] generating new properties unavailable from either component.…”

“…[10] All of these disadvantages have largely limited their practical applications in various domains.T ot ackle this problem, tremendous efforts have been made to hybridize MOFs with other materials,thus realizing the combination of their advantages and circumventing shortcomings.Avariety of MOF composites have been successfully developed, such as MOF/graphene, [11a] MOF/graphite, [11b] MOF/carbon nanotubes, [11c] MOF/polymers, [11d] MOF/enzymes, [11e] and MOF/metal nanoparticles, [11f] generating new properties unavailable from either component. [14] However, these methods are synthetically tedious and cannot retain the original crystalline morphology of MOFs.W ea im to develop stable MOF/foam composite materials by ao ne-pot procedure,w hich enables the direct preparation of high-quality composite materials.More importantly,this would provide ageneral strategy to prepare MOFs for practical applications,e specially in heterogeneous catalysis over as cope broader than ever before. [12] Eddaoudi group reported the MOF/silica composite by the stepwise layer-by-layer strategy.…”

“…Very recently,W ang and co-workers successfully developed the MOF/mesh, MOF/cloth, and MOF/sponge composites via the roll-to-roll mechanical production and utilized them for efficient particulate matter removal. [14] However, these methods are synthetically tedious and cannot retain the original crystalline morphology of MOFs.W ea im to develop stable MOF/foam composite materials by ao ne-pot procedure,w hich enables the direct preparation of high-quality composite materials.More importantly,this would provide ageneral strategy to prepare MOFs for practical applications,e specially in heterogeneous catalysis over as cope broader than ever before. [13] TheS ua nd Zhu groups also developed new hierarchical Al-metal-organic aerogels based on ap ost-synthetic process using MOFs and other additives.…”