Metal–organic frameworks (MOFs) are porous crystalline materials with a high tunability. To improve the functionality of the original frameworks, several strategies, such as the use of different ...metal cations and organic ligands and post‐synthetic modification, have been developed, enabling the use of MOFs in numerous practical applications in various fields. Recently, another approach, i.e., MOF‐on‐MOF architecturing, has been actively studied by combining two or more MOFs into a composite. MOF‐on‐MOF materials not only possess the intrinsic properties of each MOF but also exhibit unprecedented synergism within a single system, resulting in a considerable potential for various applications. This review summarizes the interesting areas of application of MOF‐on‐MOF architectures into three categories: separation, catalysis, and sensing. In particular, the synergism occurring within such MOF‐on‐MOF architectures is discussed.
To improve the functionality of the original frameworks, MOF‐on‐MOF architecturing has been actively studied by combining several MOFs into a composite. This review presents a summary of the application of the MOF‐on‐MOF architectures in separation, catalysis, and sensing. The synergism occurring within such MOF‐on‐MOF architectures is discussed particularly.
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•Atomic layer deposition (ALD) used to fabricate metal–organic framework (MOF) materials is reviewed.•Seven combined methods using ALD technology and MOF synthesis are ...discussed.•Applications of MOF materials related to ALD technology are summarized.•New directions and perspectives for ALD-related MOF materials are provided.
Atomic layer deposition (ALD) technology is an effective nanofabrication method used for various nanomaterials and thin films at the atomic level. Metal-organic framework (MOF) materials have a high porosity and specific surface area, and have been widely used in the fields of adsorption, separation, catalysis, sensors and devices. When ALD meets MOFs, some new combination methods can appear. In this review, the advances in MOFs synthesis related to ALD are summarized. These new synthetic methods of MOFs can be divided into seven categories: MOF gas-phase growth via ALD/MLD, MOF solvothermal growth on ALD metal oxide, MOF solvothermal growth and assembled on ALD metal oxide, MOF liquid-phase epitaxy growth on ALD metal oxide, MOF conversion from ALD metal oxide, MOF conversion via hydroxyl double salt from ALD metal oxide and MOF modification via ALD. Meanwhile, the upscaling applications of these ALD-related MOFs, such as in adsorption, separation, catalysis and energy, have further been reviewed. The perspectives of ALD based MOFs have also been provided. Such efforts are expected to provide guidance for developing new synthetic methods of MOFs related to ALD technology and thereby lead to new applications of ALD-related MOFs.
This paper reviews the recent progress of small angle scattering (SAS) techniques, mainly including X-ray small angle scattering technique (SAXS) and neutron small angle scattering (SANS) technique, ...in the study of metal-organic framework (MOF) colloidal materials (CMOFs). First, we introduce the application research of SAXS technique in pristine MOFs materials, and review the studies on synthesis mechanism of MOF materials, the pore structures and fractal characteristics, as well as the spatial distribution and morphological evolution of foreign molecules in MOF composites and MOF-derived materials. Then, the applications of SANS technique in MOFs are summarized, with emphasis on SANS data processing method, structure modeling and quantitative structural information extraction. Finally, the characteristics and developments of SAS techniques are commented and prospected. It can be found that most studies on MOF materials with SAS techniques focus mainly on nanoporous structure characterization and the evolution of pore structures, or the spatial distribution of other foreign molecules loaded in MOFs. Indeed, SAS techniques take an irreplaceable role in revealing the structure and evolution of nanopores in CMOFs. We expect that this paper will help to understand the research status of SAS techniques on MOF materials and better to apply SAS techniques to conduct further research on MOF and related materials.
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•MOF nanoshell materials are “star” platforms in biomedicine.•Preparation strategies of MOF nanoshell materials are systematically reviewed.•Drug delivery, biosensing, bioimaging and cancer therapy ...are involved.•Challenge and future development are prospected.
The integration of metal-organic frameworks (MOFs) and nanoshells to construct MOF nanoshell structures offers promising therapeutic platforms for biomedical applications. These MOF nanoshells, which encompass hollow-shells, core-shells, and yolk-shells, exhibit not only the inherent benefits of MOFs, such as large specific surface area, high pore volume, adjustable pore size, rapid cargo transfer and diffusion, excellent biocompatibility, and biodegradability, but also the structural advantages of nanoshells, including a large cavity, high loading capacity, and protective effects. Consequently, MOF nanoshells emerge as ideal materials for biomedical applications. The incorporation of functional nanoparticles or chemotherapeutic molecules with MOF nanoshells enables multi-component synergy due to their adjustable structures, components, and surface modifications, an aspect unattainable by single-component materials. This review article systematically introduces the synthesis strategies for various MOF nanoshells and delves into their applications in biomedicine, including drug delivery, biosensing, bioimaging, and cancer therapy. Finally, the challenges, suggestions, and future prospects of MOF nanoshell structures are discussed.
The structural, compositional, and morphological features of metal–organic frameworks (MOFs) govern their properties and applications. Construction of hybrid MOFs with complicated structures, ...components, or morphologies is significant for the development of well‐organized MOFs. An advanced route is reported for construction of atypical hybrid MOFs with unique morphologies and complicated components: 1) MOF‐on‐MOF growth of a 3D zeolitic imidazolate framework (ZIF) on a ZIF‐L template, 2) etching of a part of the 2D ZIF‐L template, and 3) structural transformation of 2D ZIF‐L into 3D ZIF. The formation of core–shell‐type MOF rings and plates is controlled by regulating the three processes. The formation route for the core–shell‐type MOF rings and plates was monitored by tracking changes in morphology, structure, and composition. Carbon materials prepared from the pyrolysis of the core–shell‐type hybrid MOFs displayed enhanced oxygen reduction reaction activities compared to their monomeric counterparts.
Well‐designed atypical hybrid metal–organic frameworks (MOFs) with unique morphologies and complicated components are constructed with regulated combinations of three distinctive processes: MOF‐on‐MOF growth, etching, and structural transformation. The resulting hybrid MOFs are utilized as precursor materials for the generation of active oxygen reduction reaction (ORR) catalysts.
Constructing MOF‐on‐MOF heterojunction with elaborate charge transfer mechanism and interface is a promising strategy for improving the photocatalytic properties of MOFs. Herein, a Step‐scheme ...(S‐scheme) MIL‐125‐NH2@CoFe Prussian blue analogue (PBA) heterojunction is reported for the first time. The MOF‐on‐MOF heterostructure exhibits a sandwich‐like morphology with hollow CoFe PBA nanocages selectively assembled on the top‐down surfaces of MIL‐125‐NH2 nanocakes. Experimental findings and theoretical simulation results reveal the formation of internal electric field via interfacial TiOCo bonds at the heterojunction, providing driving force and atomic transportation highway for accelerating the S‐scheme charge transfer and enhancing the redox performance. Contributed further by the hollow sandwich‐like structures with increased active site exposure, the designed MOF‐on‐MOF heterojunction exhibits significantly enhanced photocatalytic activity for degradation of various organic pollutants. This study provides insights toward the rational design of semiconducting MOF‐based heterojunctions with improved properties.
A S‐scheme MOF‐on‐MOF heterojunction with well‐defined TiOCo bonded interface and internal electric field is constructed with enhanced photocatalytic activity.
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•Preparations of the MOFs-COFs composites.•Applications of the MOFs-COFs composites.•Underline the potential development trend and challenges toward MOFs-COFs composites.
The research ...for metal organic frameworks (MOFs)- and covalent organic frameworks (COFs)-based functional composites has attracted continuous attention due to their excellent synergistic properties. With the increasing interest in expanding the diversity and properties of multi-component framework materials, the commonness and uniqueness of MOFs and COFs build a bridge for the potential development of meritorious MOFs-COFs composites. This minireview comprehensively introduced the recent development of MOFs-COFs composites from their syntheses to enhanced applications. Starting from the preparation methods, MOFs-mediated MOF@COF composites and COFs-mediated COF@MOF composites fabricated under various synthetic conditions are introduced, respectively. Furthermore, the enhanced application performance of the MOF@COF composites and COF@MOF composites in catalysis and their potential applications in adsorption and separation, energy storage and sensing are summarized. Followed by the above discussion, we further highlight the opportunities and challenges faced by MOFs-COFs composites. Altogether, this minireview is expected to provide inspiration for the development of the dazzling but embryonic MOFs-COFs composites.
Multiporous metal‐organic frameworks (MOFs) have emerged as a subclass of highly crystalline inorganic‐organic materials, which are endowed with high surface areas, tunable pores, and fascinating ...nanostructures. Heterostructured MOF‐on‐MOF composites are recently becoming a research hotspot in the field of chemistry and materials science, which focus on the assembly of two or more different homogeneous or heterogeneous MOFs with various structures and morphologies. Compared with one single MOF, the dual MOF‐on‐MOF composites exhibit unprecedented tunability, hierarchical nanostructure, synergistic effect, and enhanced performance. Due to the difference of inorganic metals and organic ligands, the lattice parameters in a, b, and c directions in the single crystal cells could bring about subtle or large structural difference. It will result in the composite material with distinct growth methods to obtain secondary MOF grown from the initial MOF. In this review, the authors wish to mainly outline the latest synthetic strategies of heterostructured MOF‐on‐MOFs and their derivatives, including ordered epitaxial growth, random epitaxial growth, etc., which show the tutorial guidelines for the further development of various MOF‐on‐MOFs.
Compared with one single metal‐organic framework (MOF), the dual MOF‐on‐MOF composites exhibit unprecedented tunability, hierarchical nanostructure, synergistic effect, and enhanced performance. Herein, the latest synthetic strategies of heterostructured MOF‐on‐MOFs and their derivatives are outlined, including ordered epitaxial growth, random epitaxial growth, etc., which show the tutorial guidelines for the further development of various MOF‐on‐MOFs.
2D metal‐organic frameworks‐based (2D MOF‐related) materials benefit from variable topological structures, plentiful open active sites, and high specific surface areas, demonstrating promising ...applications in gas storage, adsorption and separation, energy conversion, and other domains. In recent years, researchers have innovatively designed multiple strategies to avoid the adverse effects of conventional methods on the synthesis of high‐quality 2D MOFs. This review focuses on the latest advances in creative synthesis techniques for 2D MOF‐related materials from both the top‐down and bottom‐up perspectives. Subsequently, the strategies are categorized and summarized for synthesizing 2D MOF‐related composites and their derivatives. Finally, the current challenges are highlighted faced by 2D MOF‐related materials and some targeted recommendations are put forward to inspire researchers to investigate more effective synthesis methods.
Two strategies, top‐down and bottom‐up, are used to explore the various synthesis approaches for the 2D metal‐organic framework (MOF)‐related materials. Top‐down method includes sonication exfoliation, moderate physical exfoliation, electrochemical exfoliation, chemical intercalation, and Alkali‐etching exfoliation. Bottom‐up method includes modulation synthesis, interface synthesis, template assistance and sacrifice, and surfactant‐assisted synthesis. This review also summarizes other synthesis methods.
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•Synthesis of a novel nitrogen and oxygen-doped hierarchical porous carbon for wastewater treatment.•The PDA carbon layer provided abundant oxygen sites and altered the type of ...nitrogen in the material.•Carbonization temperature and etching time had an effect on the structural properties of carbon materials.•The maximum adsorption capacity of MO by UPCH800 (417.34 mg/g) outperformed most reported MOF-derived carbon materials.
MOF-derived carbon materials have garnered significant attention in the field of adsorption due to their abundant porosity, excellent stability, and structural diversity. In this study, nitrogen and oxygen-doped hierarchical porous carbon materials were obtained by carbonizing PDA@UiO-66-NH2 at various temperatures and subsequently etching with hydrofluoric acid for different times. The adsorption capacity of these materials towards bisphenol a (BPA), methyl orange (MO), and methylene blue (MB) was evaluated. The results suggest excessive carbonization temperature and etching time may cause the collapse of the pore structure. In addition, the introduction of a PDA carbon layer can reduce the nitrogen–oxygen ratio and modify the nitrogen species in the materials. Among these materials, UPCH800, which was carbonized at 800 °C followed by etching for 6 h, exhibits the best adsorption performance towards BPA and MO, with a maximum adsorbed amount of 350.51 and 417.34 mg/g respectively. For MB, the maximum adsorption amount is 227.53 mg/g. All adsorptions reach equilibrium within 1 h. Thermodynamic studies reveal that the adsorption of MO by UPCH800 is an entropy-driven adsorption process, while the adsorption of BPA and MB is an enthalpy-driven exothermic process. Based on experimental and characterization results, the primary adsorption mechanisms involve π-π interactions, n-π interactions, pore-filling, and hydrogen bonding between the pollutants and the material. Moreover, UPCH800 exhibits high removal efficiency after 5 adsorption cycles, making it a promising material for the adsorption of BPA and MO.
