Mesoporous Metal Research Articles

Synthesis of 2, 4 disubstituted 1, 5 benzodiazepines promoted by efficient Silica-Alumina Catalyst

An efficient and environment friendly valuable synthon of 1, 5 benzodiazepine derivatives were synthesized having unique physical and medicinal properties. This reaction is performed by mesoporous binary mixed metal oxide SiO2-Al2O3 which is synthesized by hydrothermal method at high temperature. This mesoporous material is investigated by XRD, SEM, EDS, TEM, TPD and BET surface area. Present method offers several remarkable advantages such as non-toxic, noncorrosive and easy work-up procedure for the purification of product with non-chromatographic method, ecofriendly reaction condition.

Aluminium-based MIL-100(Al) and MIL-101(Al) metal–organic frameworks, derivative materials and composites: synthesis, structure, properties and applications

This review summarizes the synthesis, properties and applications of two related and particularly interesting mesoporous aluminium-based metal–organic frameworks (MOFs): MIL-100(Al) and MIL-101(Al).

Hierarchical micro- and mesoporous metal–organic framework-based magnetic nanospheres for the nontargeted analysis of chemical hazards in vegetables

H-MOF6@Fe3O4 nanospheres for complete removal of phytochromes through size selectivity to realize nontargeted analysis of chemical hazards in vegetables.

A comparative electrochemical study of non-enzymatic glucose, ascorbic acid, and albumin detection by using a ternary mesoporous metal oxide (ZrO2, SiO2 and In2O3) modified graphene composite based biosensor.

In this study, we present an electrochemical investigation of a ternary mesoporous metal oxide (ZrO2, SiO2 and In2O3) modified graphene composite for non-enzymatic glucose, ascorbic acid, and albumin detection in urine at physiological pH. Synergetic property of ZrO2–Ag–G–SiO2 and In2O3–G–SiO2 were investigated via cyclic voltammetry (CV) using FTO glass and copper-foil electrodes with no prerequisite of solid antacid expansion. The mesoporous ZrO2–Ag–G–SiO2 and In2O3–G–SiO2 composites were synthesized and characterized using XRD, SEM, TEM, Raman spectroscopy, XPS, DRS, BET, and photocurrent measurements. Upon increasing the glucose concentration from 0 to 3 mM, CV results indicated two anodic peaks at +0.18 V and +0.42 V versus Ag/AgCl, corresponding to Zr3+ and Zr4+, respectively, considering the presence of glucose in urine. Moreover, the effects of high surface area In2O3–G–SiO2 were observed upon the examination of ZrO2–Ag–G–SiO2. In2O3–G–SiO2 demonstrated a decent electrochemical pattern in glucose, ascorbic acid, and albumin sensing. Nevertheless, insignificant synergistic effects were observed in In2O3-G, ZrO2-G, and ZrO2–G–SiO2. In2O3–G–SiO2 performed well under a wide range of electrolytes and urine, and showed no activity toward uric acid, suggesting potential for biodetection in urine.

A window-space-directed assembly strategy for the construction of supertetrahedron-based zeolitic mesoporous metal-organic frameworks with ultramicroporous apertures for selective gas adsorption.

Despite their scarcity due to synthetic challenges, supertetrahedron-based metal–organic frameworks (MOFs) possess intriguing architectures, diverse functionalities, and superb properties that make them in-demand materials. Employing a new window-space-directed assembly strategy, a family of mesoporous zeolitic MOFs have been constructed herein from corner-shared supertetrahedra based on homometallic or heterometallic trimers [M3(OH/O)(COO)6] (M3 = Co3, Ni3 or Co2Ti). These MOFs consisted of close-packed truncated octahedral cages possessing a sodalite topology and large β-cavity mesoporous cages (∼22 Å diameter) connected by ultramicroporous apertures (∼5.6 Å diameter). Notably, the supertetrahedron-based sodalite topology MOF combined with the Co2Ti trimer exhibited high thermal and chemical stability as well as the ability to efficiently separate acetylene (C2H2) from carbon dioxide (CO2).

Recent advances in mechanochemical synthesis of mesoporous metal oxides

This review presents advances and challenges in the mechanochemical synthesis of mesoporous metal oxides with uniform porosity.

Ordered mesoporous metal oxides for electrochemical applications: correlation between structure, electrical properties and device performance.

Ordered mesoporous metal oxides with a high specific surface area, tailored porosity and engineered interfaces are promising materials for electrochemical applications. In particular, the method of evaporation-induced self-assembly allows the formation of nanocrystalline films of controlled thickness on polar substrates. In general, mesoporous materials have the advantage of benefiting from a unique combination of structural, chemical and physical properties. This Perspective article addresses the structural characteristics and the electrical (charge-transport) properties of mesoporous metal oxides and how these affect their application in energy storage, catalysis and gas sensing.

Highly Mesoporous Hybrid Transition Metal Oxide Nanowires for Enhanced Adsorption of Rare Earth Elements from Wastewater

Removal of rare earth elements (REEs) from industrial wastewater is a continual challenge. To date, several approaches to the synthesis of nanoadsorbants for this application have been reported, although these are characterized by insufficient adsorption capacity and limitations in cycling stability. The present work reports the fabrication and performance of hierarchical hybrid transition metal oxide (TMO) nanowires deposited on carbon fibers. An ordered assembly of hybrid TMO nanowires exhibits an outstanding adsorbance of 1000 mg·g-1 of REEs with 93% recyclability. This superior performance is attributed to the unique mesoporous architecture of the nanowires, which exhibits a high surface area of 122 cm3·g-1. Further, rapid adsorption/desorption of the REEs reveals minimal morphological alteration and hence high structural stability of these hybrid TMO nanowires after multiple cycles. The ready accessibility of the adsorption sites at crystallite boundaries and the surfaces as well as rapid adsorption of the REEs on the mesoporous nanostructure facilitate considerable adsorption capacity, improved structural stability, and extended cyclability, all of which suggest the potential for this material in REE extraction.

Assembly of Two Mesoporous Anionic Metal-Organic Frameworks for Fluorescent Sensing of Metal Ions and Organic Dyes Separation.

Anionic metal-organic frameworks (MOFs) have attracted increasing attention due to the enhanced electrostatic interactions between their anionic frameworks and counter-ionic guests. Owing to these special host-guest interactions, anionic MOFs are beginning to have a large impact in the field of absorption and separation of ionic molecules and selective sensing of metal ions. Herein, two mesoporous anionic metal-organic frameworks, namely, [(CH3)2NH2]6[In6(OX)6(TCA)4]·solvents (JOU-11) and [(CH3)2NH2]6[In6(OX)6(TCPA)4]·solvents (JOU-12) (H3TCA = tricarboxytriphenylamine; H3TCPA = tris((4-carboxyl)phenylduryl)amine; OX = oxalate), have been synthesized by using wheel-type [In6(OX)6(COO)12]6- as building blocks. Structural analyses show that JOU-11 and JOU-12 show isoreticular three-dimensional frameworks with pyr topology. Due to their anionic frameworks and tunable pore window sizes, both compounds can be exploited for absorbing and separating cationic organic dyes. In addition, JOU-11 can be developed as a fluorescence "turn-off" sensor for selectively sensing Fe3+, whereas JOU-12 can be used for fluorescence "turn-on" sensing of Cu2+ and Co2+ ions.

Amorphous Alloy Architectures in Pore Walls: Mesoporous Amorphous NiCoB Alloy Spheres with Controlled Compositions via a Chemical Reduction

Amorphous bimetallic borides are an emerging class of catalytic nanomaterial that has demonstrated excellent catalytic performance due to its glass-like structure, abundant unsaturated active sites, and synergistic electronic effects. However, the creation of mesoporous Earth-abundant bimetallic metal borides with tunable metal proportion remains a challenge. Herein, we develop a sophisticated and controllable dual-reducing agent strategy to synthesize the mesoporous nickel-cobalt boron (NiCoB) amorphous alloy spheres (AASs) with adjustable compositions by using a soft template-directed assembly approach. The selective use of tetrabutylphosphonium bromide (Bu4PBr) is beneficial to generate well-defined mesopores because it both moderates the reduction rate by decreasing the reducibility of M2+ species and prevents the generation of soap bubbles. Our meso-Ni10.0Co74.5B15.5 AASs generate the highest catalytic performance for the hydrolytic dehydrogenation of ammonia borane (AB). Its high performance is attributed to the combination of optimal synergistic effects between Ni, Co, and B as well as the high surface area and the good mass transport efficiency due to the open mesopores. This work describes a systematic approach for the design and synthesis of mesoporous bimetallic borides as efficient catalysts.

Bicontinuous Mesoporous Metal Foams with Enhanced Conductivity and Tunable Pore Size and Porosity via Electrodeposition for Electrochemical and Thermal Systems

Mesoporous metals are used in applications requiring high specific surface area and fast mass transport in an electrically conductive network and are primarily produced via dealloying. However, dea...

Iron-Mineralization-Induced Mesoporous Metal-Organic Frameworks Enable High-Efficiency Synergistic Catalysis of Natural/Nanomimic Enzymes.

Metal-organic frameworks (MOFs) have become a promising accommodation for enzyme immobilization and protection. However, the integration of multienzymes into MOFs may result in compromise of individual enzymatic activity. In this work, we report an iron mineralization strategy to facilely construct a mesoporous MOF, possessing excellent peroxidase-mimic bioactivity. Furthermore, the feasibility of in situ encapsulating natural enzymes within the developed mesoporous MOF nanozymes endows these natural/nanomimic enzyme hybrids with remarkably enhanced synergistic catalysis ability. Such activity enhancement is mainly due to (1) the fast flux rate of substances through the interconnected mesoporous channels and (2) the simultaneously increased loading amount of enzymes and iron within the MOFs caused by the iron mineralization process.

Robotic Catalysis: A High‐Throughput Method for Miniature Screening of Mesoporous Metal Oxides**

AbstractWe have developed a high‐throughput system to synthesise and explore up to 96 heterogeneous catalysts at the same time. The system was developed as a proof of concept, using a standard glass plate and a 3D printed 96‐well plate. Nano‐droplets of catalyst formulations were transferred to the glass plate using an acoustic liquid handler and upon heat treatments, the miniature mesoporous metal oxide (MMO) catalysts were formed. The 3D printed bottomless 96‐well plate was fixed to the glass plate, to give 96 individual wells, each containing a catalyst. Four catalyst plates were prepared (Co3O4‐, Au/Co3O4‐, Pd/Co3O4‐ and Co/Mn‐MMO) to be screened for their activity in the oxidation of morin, as a model reaction. The observed reaction rates (kobs) for each catalyst were calculated to identify the most active catalyst. The general method described herein requires microscopic amounts of catalysts with derivates of the catalyst's composition.

Enantioselective Voltammetric Sensors on the Basis of Chiral Materials

The review presents exhaustive information for the last 5 years on the trends and methods of research, development, and application of enantioselective voltammetric sensors on the basis of new chiral materials for the recognition of enantiomers of biologically active and medicinal compounds. Enantioselective sensors on the basis of chiral Cu, Au, Ag, Pt, and Pd nanoparticles and single crystals, mesoporous metals with molecular imprints, single-wall carbon nanotubes, smart polymers, metal–organic frameworks and supramolecular assemblies, and chiral ionic liquids are considered. Examples of the recognition and determination of enantiomers in various samples and analytical characteristics of the proposed sensors are given. Problems and prospects of using enantioselective voltammetric sensors for the chiral recognition of optically active compounds are discussed.

Nanoporous Co/Mn-Mixed Metal Oxides Templated via Polysulfones for Amine Oxidation

Herein, we report syntheses of microporous and mesoporous mixed metal oxides templated via an anionic surfactant. The effects of acid treatment, solvent type, and the amount of metal incorporation ...

Extremely fast electrochromic supercapacitors based on mesoporous WO3 prepared by an evaporation-induced self-assembly

Mesoporous metal oxides consisting of fully interconnected network structures with small pores (20–50 nm) have high surface areas and decreased ion intercalation distances, making them ideal for use in high-performance electrochromic supercapacitors (ECSs). Evaporation-induced self-assembly (EISA), which combines sol–gel chemistry and molecular self-assembly, is a powerful method for the fabrication of mesoporous metal oxides through a solution phase synthesis. Herein, we introduce ultrafast sub-1 s ECSs based on an amorphous mesoporous tungsten trioxide (WO3) that is prepared by EISA. Compared to that of a compact-WO3 film-based device, the performances of an ECS with mesoporous WO3 exhibits a large optical modulation (76% at 700 nm), ultrafast switching speeds (0.8 s for coloration and 0.4 s for bleaching), and a high areal capacitance (2.57 mF/cm2), even at a high current density (1.0 mA/cm2). In addition, the excellent device stability during the coloration/bleaching and charging/discharging cycles is observed under fast response conditions. Moreover, we fabricated a patterned mesoporous WO3 for ECS displays (ECSDs) via printing-assisted EISA (PEISA). The resulting ECSDs can be used as portable energy-storage devices, and their electrochromic reflective displays change color according to their stored energy level. The ECSDs in this work have enormous potential for use in next-generation smart windows for buildings and as portable energy storage displays.

4D in Situ Temperature-Dependent Study on Morphological and Chemical Evolution of Metals in Molten Salt Environments By Multimodal Microscopy

To further the development of sustainable energy, it is necessary to understand material behavior under extreme environments. The need to transport high-temperature heat in next-generation nuclear or large-scale solar thermal power plants drives increased interest in molten halide salts as a heat transfer fluid. Specifically, molten KCl-MgCl2 and related mixtures are attractive, as they have some of the highest volumetric heat capacities of viable systems at 700 oC and lowest cost. However, the prevalent challenge for molten KCl-MgCl2 is corrosion with the encasing structural Ni-based alloys. Literature has shown that this corrosion generally proceeds through the selective dissolution of Cr along with intergranular corrosion. Our prior work showed that in addition to intergranular corrosion, a percolation dealloying phenomenon can contribute to the morphological changes of metal corrosion in molten salt; this dealloying process leads to a porous structure formation instead of corrosion along the grain boundaries. However, the underlying conditions and kinetics that determine the dominating phenomenon remain unclear.In our present study, binary Ni-20Cr (wt. %) alloy was studied in molten KCl-MgCl2 (50 – 50 mol. %) at elevated temperatures (500, 600, 700 and 800 oC) by multimodal X-ray and electron microscopy techniques. In situ synchrotron X-ray nano-tomography was used to observe the real-time morphological evolution. 3D visualizations present apparently different pathways for the material’s morphological evolution at different temperatures. With quantification of morphological characteristics, including relative volume change, porosity, feature size distribution and corrosion distance propagation as a functions of temperature and time, possible rate-determining factors are discussed, including long-range diffusion-control (such as dissolved Cr ions diffusing outward or salt ions diffusing inward) vs. interface-control (such as surface diffusion or reaction at the interfaces). Furthermore, by X-ray Absorption Near-Edge Structure (XANES) spectroscopic imaging, the oxidation state of Ni in the remaining sample was analyzed. In addition, high-resolution Transmission Electron Microscopy with Energy-Dispersive X-ray Spectroscopy was applied to observe the corrosion products at the surface of the alloy and salt penetration at the nanoscale. Overall, this study reveals the temperature-dependent corrosion behavior of Ni-20Cr alloy in molten KCl-MgCl2 salts, which could be applied to improve the materials used in large-scale energy facilities such as nuclear and solar power plants, highlighting the importance of considering temperature-dependent kinetics routes. On the broader impact, the knowledge could be applied to a wider community, such as when utilizing the molten salt dealloying phenomena to fabricate nano-/mesoporous metals for functional applications. This work was supported as part of the Molten Salts in Extreme Environments (MSEE) Energy Frontier Research Center (EFRC), funded by the U.S. Department of Energy Office of Science.

Purified mesoporous nickel metal organic framework as electrocatalyst for hydrogen evolution reaction (HER) in basic medium

Metal organic framework or MOFs are found to be a good catalyst for hydrogen evolution in view of its excellent structural features like porous nature and well-defined morphology. This report describes the synthesis of Nickel-MOF prepared by solvothermal approach and further purified by a chemical process. Both impure and purified Nickel-MOFs are fabricated as electrodes for evaluating HER reaction. The performance towards electrocatalytic activity is affected due to the impurities present in the porous structure. In view of investigating the effect of activation/purification process towards morphology and in-turn HER activity, activation and purification is carried out to enhance the performance of MOFs. The electrochemical characterization proves high electrocatalytic activity for purified Ni-MOF with high rate kinetics towards HER than impure Ni-MOF. The Tafel slope of purified Nickel MOF is estimated to be 73.7 mV/dec with a low charge transfer resistance of 1.84 Ω, whereas the unpurified Ni-MOF shows 87.47 mV/dec and 3.85 Ω. Results show that pure Ni-MOF has abundant catalytic active edge sites and obeys Volmer-Heyrvosky mechanism with makes desorption of hydrogen as rate determining step.

Introducing a Cantellation Strategy for the Design of Mesoporous Zeolite-like Metal-Organic Frameworks: Zr-sod-ZMOFs as a Case Study.

Herein we report novel mesoporous zirconium-based metal-organic frameworks (MOFs) with zeolitic sodalite (sod) topology. Zr-sod-ZMOF-1 and -2 are constructed based on a novel cantellation design strategy. Distinctly, organic linkers are judiciously designed in order to promote the deployment of the 12-coordinated Zr hexanuclear molecular building block (MBB) as a tetrahedral secondary building unit, a prerequisite for zeolite-like nets. The resultant Zr-sod-ZMOFs exhibit mesopores with a diameter up to ≈43 Å, while the pore volume of 1.98 cm3·g-1 measured for Zr-sod-ZMOF-1 is the highest reported experimental value for zeolite-like MOFs based on MBBs as tetrahedral nodes.

Nanoscale Hierarchically Micro- and Mesoporous Metal-Organic Frameworks for High-Resolution and High-Efficiency Capillary Electrochromatographic Separation.

Metal-organic frameworks (MOFs) have been widely applied in a variety of fields. However, most of the developed MOFs are micrometer scale in crystal size and contain only micropores, which will limit the mass transport and diffusion of various analytes into their internal interaction sites, severely restricting the potential of MOFs in separation science. Herein, nanoscale hierarchically porous MOFs (NHP-MOFs) were first explored as a novel MOF-based stationary phase with excellent mass transfer performance and abundant accessible interaction sites for high-performance chromatographic separation. As a proof-of-concept demonstration, the nanoscale hierarchically micro- and mesoporous UiO-66 (NHP-UiO-66) was firmly immobilized on the capillary inner surface and utilized as the porous stationary phase for high-resolution and high-efficiency electrochromatographic separation. A wide range of low-, medium-, and high-molecular-weight analytes, including substituted benzenes, chlorobenzenes, polycyclic aromatic hydrocarbons, nucleosides, polypeptides, and proteins were all separated well on a NHP-UiO-66-coated column with excellent resolution and repeatability, exhibiting significantly improved column efficiency and separation ability compared to those of a microporous UiO-66-modified column. The maximum column efficiencies for all the six kinds of analytes reached up to 1.2 × 105 plates/m, and the relative standard deviations of the migration times of substituted benzenes for intraday, interday, and column-to-column were all lower than 5.8%. These results reveal that NHP-MOFs can effectively combine the advantages of the high specific surface area of microporous MOFs and the excellent mass transfer performance and abundant accessible interaction sites of NHP materials, possessing great prospect for high-performance chromatographic separation.