Microwaves induced epitaxial growth of urchin like MIL-53(Al) crystals on ceramic supports

Shaping Metal-Organic Frameworks (MOFs) poses a significant challenge for their widespread application on a large scale. In particular, a precise control over crystal orientation and arrangement on substrates are expected to provide exiting opportunities for novel materials with customized characteristics and enhanced performance in catalysis, gas storage, sensing, optics and electronics. Here we demonstrated for the first time that microwave irradiation can induce well controlled epitaxial growth of urchin-like MIL-53(Al) crystals via the hydrothermal conversion of Atomic Layer Deposition alumina layers on SiC foams. The resulting large, ordered crystals feature specific size, homogeneity, dispersion, and quantity that strongly correlate with the nature of the ceramic support and its ability to absorb microwaves. Furthermore, the supported MIL-53(Al) urchins were considered as templates for generating nanostructured alumina fibers on SiC foams, providing attractive catalyst carriers with high specific surface areas.

Principles of Design and Synthesis of Metal Derivatives from MOFs

Materials derived from metal-organic frameworks (MOFs) have demonstrated exceptional structural variety and complexity and can be synthesized using low-cost scalable methods. Although the inherent instability and low electrical conductivity of MOFs are largely responsible for their low uptake for catalysis and energy storage, a superior alternative is MOF-derived metal-based derivatives (MDs) as these can retain the complex nanostructures of MOFs while exhibiting stability and electrical conductivities of several orders of magnitude higher. The present work comprehensively reviews MDs in terms of synthesis and their nanostructural design, including oxides, sulfides, phosphides, nitrides, carbides, transition metals, and other minor species. The focal point of the approach is the identification and rationalization of the design parameters that lead to the generation of optimal compositions, structures, nanostructures, and resultant performance parameters. The aim of this approach is to provide an inclusive platform for the strategies to design and process these materials for specific applications. This work is complemented by detailed figures that both summarize the design and processing approaches that have been reported and indicate potential trajectories for development. The work is also supported by comprehensive and up-to-date tabular coverage of the reported studies.

Rational design of a functionalized aluminum metal-organic framework as a turn-off fluorescence sensor for α-ketoglutaric acid

A 3D metal-organic framework (MOF) called Al-DUT-5-N2H3 (1) (DUT: Dresden University of Technology) was prepared hydrothermally using Al(iii) salt and a hydrazinyl functionalized linker called 2-hydrazinyl-[1,1'-biphenyl]-4,4'-dicarboxylic acid (BPDC-N2H3). Material 1 was successfully characterized by X-ray powder diffraction (XRPD), FT-IR spectroscopy, N2 sorption (BET) experiment, thermogravimetric analysis (TGA), EDX and FE-SEM analyses. The activated form of material 1 (called 1') was achieved by a direct heating process. Material 1' was successfully employed for the solution-phase fluorescence detection of α-ketoglutaric acid (α-KG). It showed high detection performance even when there were other competitive analytes present in the mixture. Material 1' is the first MOF-based fluorescent turn-off sensor for the detection of α-KG. The response time for α-KG is exceptionally low (60 s) as compared to any other reported α-KG sensor. The limit of detection (LOD) was found to be 0.61 μM, which is far better as compared to any other reported sensor for α-KG to date. The mechanism for α-KG sensing was thoroughly investigated and proposed to be PET (photoinduced electron transfer) process by TD-DFT (time-dependent DFT) calculations.

Al-based metal organic framework derived self-assembled carbon nanosheets as innovative anodes for Li- and Na-ion batteries

Functional modification and structural design of carbon electrode materials are considered as a cost-effective method to improve their electrochemical performance. In this study, a solvothermal method is applied to realize self-assembly of the metal-organic framework. After simple carbonization and acid treatment, carbon nanosheets with 2D adjustable defective sub-units are successfully prepared for the first time. It is found that carbonization temperature has a significant effect on the carbon skeleton structure. The optimal nanostructures with large specific surface area and appropriate pore size distribution make self-assembled carbon nanosheets having excellent Li/Na-ion storage properties. In addition, the adjustable carbon skeleton structure can effectively avoid irreversible damage when charge-discharge cycles. For Li-ion batteries, a specific capacity of 825 mAh g^-1 is achieved after 100 cycles at 100 mA g^-1, while for Na-ion batteries a specific capacity of 193 mAh g^-1 is observed after 100 cycles at 100 mA g^-1. Moreover, for Na-ion batteries, even at a high rate of 1000 mA g^-1 the material delivers a specific capacity of 109.5 mAh g^-1 after 3500 cycles.

Metal–Organic Framework (MOF)-based CO2 Adsorbents

Rising CO2 levels in the atmosphere resulting from fossil fuel combustion is one of the most significant global environmental concerns. Carbon capture and sequestration (CCS), primarily post-combustion CO2 capture, is an essential research area to reduce CO2 levels and avoid environmental destabilization. Recently, metal–organic frameworks (MOFs) have been attracting attention in the scientific community for potential applications in gas storage and separation, including CCS, owing to their novel properties, such as a large surface area, tunable pore shape and size, and tailored chemical functionality. This chapter starts with a brief introduction about the significance of CO2 adsorption and separation, followed by how MOF-based research endeavors were initiated and explored, and why MOFs are unique for gas adsorption. Secondly, we reviewed the relationship between CO2 adsorption and MOF properties including surface area, pore size and volume, amine functionality, nature of linkers, and structural flexibility, and analyzed the reported data based on the possible adsorption mechanism. The humidity effects on CO2 capture over MOFs and implementation of MOF composites were considered as well. Finally, some conclusions on the status of the developed MOFs and perspectives for future research on MOFs for the practical application of CO2 adsorption and separation were mentioned.

Facile and template-free solvothermal synthesis of mesoporous/macroporous metal–organic framework nanosheets

A facile and template-free solvothermal method was developed as a bottom-up approach to synthesize mesoporous/macroporous MOF nanosheets in a simple and scalable way. It was found that starting coordination complexes of different copper(ii)-ligand compounds mediated the controlled growth and morphology of MOF crystals. By controlling the size and shape of the MOF crystals, the possibility to adjust and tailor the structure and performances of the assemblies was demonstrated. This work provides a bottom-up approach to synthesize MOF films and nanosheets in a simple and scalable way, which may have potential in energy and biomedical applications.

A facile and template-free solvothermal method was developed as a bottom-up approach to synthesize mesoporous/macroporous MOF nanosheets in a simple and scalable way.