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Gas storage and separation are closely associated with the alleviation of greenhouse effect, the widespread use of clean energy, the control of toxic gases, and various other aspects ...in human society. In this review, we highlight the recent advances in gas storage and separation using metal-organic frameworks (MOFs). In addition to summarizing the gas uptakes of some benchmark MOFs, we emphasize on the desired chemical properties of MOFs for different gas storage/separation scenarios. Greenhouse gases (CO2), energy-related gases (H2 and CH4), and toxic gases (CO and NH3) are covered in the review.
Metal–organic frameworks (MOFs) are an emerging class of porous materials with potential applications in gas storage, separations, catalysis, and chemical sensing. Despite numerous advantages, ...applications of many MOFs are ultimately limited by their stability under harsh conditions. Herein, the recent advances in the field of stable MOFs, covering the fundamental mechanisms of MOF stability, design, and synthesis of stable MOF architectures, and their latest applications are reviewed. First, key factors that affect MOF stability under certain chemical environments are introduced to guide the design of robust structures. This is followed by a short review of synthetic strategies of stable MOFs including modulated synthesis and postsynthetic modifications. Based on the fundamentals of MOF stability, stable MOFs are classified into two categories: high‐valency metal–carboxylate frameworks and low‐valency metal–azolate frameworks. Along this line, some representative stable MOFs are introduced, their structures are described, and their properties are briefly discussed. The expanded applications of stable MOFs in Lewis/Brønsted acid catalysis, redox catalysis, photocatalysis, electrocatalysis, gas storage, and sensing are highlighted. Overall, this review is expected to guide the design of stable MOFs by providing insights into existing structures, which could lead to the discovery and development of more advanced functional materials.
Stable metal–organic frameworks (MOFs) with high resistance to harsh chemical environments are reviewed with regard to recent progress in their research and development. Fundamental mechanisms of MOF stability, the design and synthesis of stable MOF architectures, and their latest applications are summarized, providing a fundamental outline for the discovery of new stable MOFs.
Enzymatic catalytic processes possess great potential in chemical manufacturing, including pharmaceuticals, fuel production and food processing. However, the engineering of enzymes is severely ...hampered due to their low operational stability and difficulty of reuse. Here, we develop a series of stable metal-organic frameworks with rationally designed ultra-large mesoporous cages as single-molecule traps (SMTs) for enzyme encapsulation. With a high concentration of mesoporous cages as SMTs, PCN-333(Al) encapsulates three enzymes with record-high loadings and recyclability. Immobilized enzymes that most likely undergo single-enzyme encapsulation (SEE) show smaller Km than free enzymes while maintaining comparable catalytic efficiency. Under harsh conditions, the enzyme in SEE exhibits better performance than free enzyme, showing the effectiveness of SEE in preventing enzyme aggregation or denaturation. With extraordinarily large pore size and excellent chemical stability, PCN-333 may be of interest not only for enzyme encapsulation, but also for entrapment of other nanoscaled functional moieties.
Despite numerous inherent merits of metal–organic frameworks (MOFs), structural fragility has imposed great restrictions on their wider involvement in many applications, such as in catalysis. Herein, ...a strategy for enhancing stability and enabling functionality in a labile Zr(IV)‐MOF has been proposed by in situ porphyrin substitution. A size‐ and geometry‐matched robust linear porphyrin ligand 4,4′‐(porphyrin‐5,15‐diyl)dibenzolate (DCPP2−) is selected to replace the 4,4′‐(1,3,6,8‐tetraoxobenzolmn3,8phenanthroline‐2,7(1H,3H,6H,8H)‐diyl)dibenzoate (NDIDB2−) ligand in the synthesis of BUT‐109(Zr), affording BUT‐110 with varied porphyrin contents. Compared to BUT‐109(Zr), the chemical stability of BUT‐110 series is greatly improved. Metalloporphyrin incorporation endows BUT‐110 MOFs with high catalytic activity in the photoreduction of CO2, in the absence of photosensitizers. By tuning the metal species and porphyrin contents in BUT‐110, the resulting BUT‐110‐50%‐Co is demonstrated to be a good photocatalyst for selective CO2‐to‐CO reduction, via balancing the chemical stability, photocatalytic efficiency, and synthetic cost. This work highlights the advantages of in situ ligand substitution for MOF modification, by which uniform distribution and high content of the incoming ligand are accessible in the resulting MOFs. More importantly, it provides a promising approach to convert unstable MOFs, which mainly constitute the vast MOF database but have always been neglected, into robust functional materials.
The in situ porphyrin substitution strategy is developed for modifying labile interpenetrated BUT‐109(Zr), affording BUT‐110 with enhanced chemical stability and photocatalytic activity. By tuning the species and contents of metalloporphyrin in BUT‐110, some of the BUT‐110 MOFs may serve as potential photocatalysts for selective CO2‐to‐CO reduction, in the absence of photosensitizer.
We successfully assembled the photocatalytic titanium-oxo cluster and photosensitizing porphyrinic linker into a metal-organic framework (MOF), namely PCN-22. A preformed titanium-oxo carboxylate ...cluster is adopted as the starting material to judiciously control the MOF growth process to afford single crystals. This synthetic method is useful to obtain highly crystalline titanium MOFs, which has been a daunting challenge in this field. Moreover, PCN-22 demonstrated permanent porosity and photocatalytic activities toward alcohol oxidation.
The productivity of continuously cycled atmospheric water harvesting methods using metal-organic frameworks (MOFs) has been limited by a lack of scalable designs and robust MOF form factors ...compatible with rapid heat and mass transport. Explored here is the fluidization of MOF-801 powder in its native particulate form as a water vapor sorption unit. Fluidization results in a very high sorbent-air interface area and small distances over which mass diffusion must occur. This arrangement enables adsorption and desorption cycling with periods of 26 and 36 min at, respectively, 18% and 39% relative humidity (RH) with ∼80% of MOF-801 uptake capacity. This results in dynamic steady-state operation water vapor harvesting rates of 0.33 L/h/kgMOF at 18% RH (40 cycles per day at 22°C) and 0.52 L/h/kgMOF at 39% RH (55 cycles per day at 23.5°C). The measurements may have direct application to water harvesting systems.
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