Showing papers on "Mesoporous material published in 2016"
TL;DR: A review of mesoporous materials can be found in this paper, where the authors summarize the primary methods for preparing mesopore materials and discuss their applications as electrodes and/or catalysts in solar cells, solar fuel production, rechargeable batteries, supercapacitors and fuel cells.
Abstract: To meet the growing energy demands in a low-carbon economy, the development of new materials that improve the efficiency of energy conversion and storage systems is essential. Mesoporous materials offer opportunities in energy conversion and storage applications owing to their extraordinarily high surface areas and large pore volumes. These properties may improve the performance of materials in terms of energy and power density, lifetime and stability. In this Review, we summarize the primary methods for preparing mesoporous materials and discuss their applications as electrodes and/or catalysts in solar cells, solar fuel production, rechargeable batteries, supercapacitors and fuel cells. Finally, we outline the research and development challenges of mesoporous materials that need to be overcome to increase their contribution in renewable energy applications. Mesoporous materials are finding increasing uses in energy conversion and storage devices. This Review highlights recent developments in the synthesis of mesoporous materials and their applications as electrodes and/or catalysts in solar cells, solar fuel production, rechargeable batteries, supercapacitors and fuel cells.
949 citations
TL;DR: With the unique structural advantages for aligned energy levels, electron transfer, light harvesting, and the richly available reaction sites, the as-prepared monolayer of mesoporous g-C3N4 nanomesh exhibits a superior photocatalytic hydrogen evolution rate and an apparent quantum efficiency.
Abstract: Delamination of layer materials into two-dimensional single-atom sheets has induced exceptional physical properties, including large surface area, ultrahigh intrinsic carrier mobility, pronounced changes in the energy band structure, and other properties. Here, atomically thin mesoporous nanomesh of graphitic carbon nitride (g-C3N4) is fabricated by solvothermal exfoliation of mesoporous g-C3N4 bulk made from thermal polymerization of freeze-drying assembled Dicyandiamide nanostructure precursor. With the unique structural advantages for aligned energy levels, electron transfer, light harvesting, and the richly available reaction sites, the as-prepared monolayer of mesoporous g-C3N4 nanomesh exhibits a superior photocatalytic hydrogen evolution rate of 8510 μmol h(-1) g(-1) under λ > 420 nm and an apparent quantum efficiency of 5.1% at 420 nm, the highest of all the metal-free g-C3N4 nanosheets photocatalysts.
815 citations
TL;DR: In this paper, a possible enhanced photocatalytic mechanism of g-C 3 N 4 /TiO 2 heterojunction photocatalyst was proposed, which is attributed to high surface area and heterostructure formation.
Abstract: Mesoporous photocatalytic materials with macroporous structures have attracted more and more attention because of their textural mesopores and intrinsic interconnected pore networks, which are able to efficiently transport guest species to framework binding sites. In this work, macro/mesoporous g-C 3 N 4 /TiO 2 heterojunction photocatalysts were fabricated without templates or additives by a facile calcination method using tetrabutyl titanate and melamine as the feedstocks. Photocatalytic experiments of the as-prepared samples were measured by the photocatalytic oxidation degradation of RhB solution at room temperature under visible light irradiation. The results indicated that the melamine content in the precursors had an important influence on photocatalytic activity of the as-prepared samples. At the optimal loading content, the apparent reaction rate constant ( k ) was 47.8 × 10 −3 min −1 for RhB degradation, exceeding that of pure TiO 2 (6.6 × 10 −3 min −1 ) and g-C 3 N 4 (15.2 × 10 −3 min −1 ) by factor of 7.2 and 3.1 respectively. The improved photocatalytic activity was attributed to high surface area and heterostructure formation of g-C 3 N 4 /TiO 2 composites. The trapping experiment results showed that O 2 − and h + were main active species in the decomposition of RhB. A possible enhanced photocatalytic mechanism of g-C 3 N 4 /TiO 2 heterojunction photocatalysts was proposed.
539 citations
TL;DR: The results reveal a platform based on porous covalent organic frameworks for proton conduction and achieve proton conductivities that are 2-4 orders of magnitude higher than those of microporous and non-porous polymers.
Abstract: Progress over the past decades in proton-conducting materials has generated a variety of polyelectrolytes and microporous polymers. However, most studies are still based on a preconception that large pores eventually cause simply flow of proton carriers rather than efficient conduction of proton ions, which precludes the exploration of large-pore polymers for proton transport. Here, we demonstrate proton conduction across mesoporous channels in a crystalline covalent organic framework. The frameworks are designed to constitute hexagonally aligned, dense, mesoporous channels that allow for loading of N-heterocyclic proton carriers. The frameworks achieve proton conductivities that are 2-4 orders of magnitude higher than those of microporous and non-porous polymers. Temperature-dependent and isotopic experiments revealed that the proton transport in these channels is controlled by a low-energy-barrier hopping mechanism. Our results reveal a platform based on porous covalent organic frameworks for proton conduction.
519 citations
TL;DR: The TiN-S composite cathode exhibits superior performance because of higher electrical conductivity and the capture of the soluble intermediate species of the electrode reactions by 2-5 nm mesopores and strong N-S surface bonding.
Abstract: The TiN-S composite cathode exhibits superior performance because of higher electrical conductivity and the capture of the soluble intermediate species of the electrode reactions by 2-5 nm mesopores and strong N-S surface bonding.
518 citations
TL;DR: It is shown that the infiltration of perovskite precursor solutions into the pores of mesoporous silica, followed by drying, leads to the template-assisted formation of perOVskite NCs, and the most striking outcome is very bright PL with quantum efficiencies exceeding 50%.
Abstract: Colloidal lead halide perovskite nanocrystals (NCs) have recently emerged as a novel class of bright emitters with pure colors spanning the entire visible spectral range. Contrary to conventional quantum dots, such as CdSe and InP NCs, perovskite NCs feature unusual, defect-tolerant photophysics. Specifically, surface dangling bonds and intrinsic point defects such as vacancies do not form midgap states, known to trap carriers and thereby quench photoluminescence (PL). Accordingly, perovskite NCs need not be electronically surface-passivated (with, for instance, ligands and wider-gap materials) and do not noticeably suffer from photo-oxidation. Novel opportunities for their preparation therefore can be envisaged. Herein, we show that the infiltration of perovskite precursor solutions into the pores of mesoporous silica, followed by drying, leads to the template-assisted formation of perovskite NCs. The most striking outcome of this simple methodology is very bright PL with quantum efficiencies exceeding 5...
471 citations
TL;DR: In this article, a simple and scalable synthesis route is developed to prepare amorphous FeOOH quantum dots (QDs) and FeOH QDs/graphene hybrid nanosheets.
Abstract: Previous research on iron oxides/hydroxides has focused on the crystalline rather than the amorphous phase, despite that the latter could have superior electrochemical activity due to the disordered structure. In this work, a simple and scalable synthesis route is developed to prepare amorphous FeOOH quantum dots (QDs) and FeOOH QDs/graphene hybrid nanosheets. The hybrid nanosheets possess a unique heterostructure, comprising a continuous mesoporous FeOOH nanofilm tightly anchored on the graphene surface. The amorphous FeOOH/graphene hybrid nanosheets exhibit superior pseudocapacitive performance, which largely outperforms the crystalline iron oxides/hydroxides-based materials. In the voltage range between −0.8 and 0 V versus Ag/AgCl, the amorphous FeOOH/graphene composite electrode exhibits a large specific capacitance of about 365 F g−1, outstanding cycle performance (89.7% capacitance retention after 20 000 cycles), and excellent rate capability (189 F g−1 at a current density of 128 A g−1). When the lower cutoff voltage is extended to −1.0 and −1.25 V, the specific capacitance of the amorphous FeOOH/graphene composite electrode can be increased to 403 and 1243 F g−1, respectively, which, however, compromises the rate capability and cycle performance. This work brings new opportunities to design high-performance electrode materials for supercapacitors, especially for amorphous oxides/hydroxides-based materials.
412 citations
TL;DR: Hierarchical tetragonal microtubes consisting of ultrathin mesoporous NiCo2O4 nanosheets have been obtained by annealing nickel cobalt layered double hydroxide microTubes which are synthesized by a one-step solvothermal method as discussed by the authors.
Abstract: Hierarchical tetragonal microtubes consisting of ultrathin mesoporous NiCo2O4 nanosheets have been obtained by annealing nickel cobalt layered double hydroxide microtubes which are synthesized by a one-step solvothermal method. Benefiting from the unique structural features, these hierarchical NiCo2O4 microtubes manifest an excellent electrochemical performance in terms of high specific capacitance and remarkable cycle life as a battery-type electrode for hybrid supercapacitors.
394 citations
TL;DR: In this paper, an ordered mesoporous thin films of MoS2 can be utilized as a pseudocapacitive energy storage material with a specific capacity of 173 mAh g−1 for Li-ions and 118 m Ah g− 1 for Na-ions at 1 mV s−1.
Abstract: The ion insertion properties of MoS2 continue to be of widespread interest for energy storage. While much of the current work on MoS2 has been focused on the high capacity four-electron reduction reaction, this process is prone to poor reversibility. Traditional ion intercalation reactions are highlighted and it is demonstrated that ordered mesoporous thin films of MoS2 can be utilized as a pseudocapacitive energy storage material with a specific capacity of 173 mAh g−1 for Li-ions and 118 mAh g−1 for Na-ions at 1 mV s−1. Utilizing synchrotron grazing incidence X-ray diffraction techniques, fast electrochemical kinetics are correlated with the ordered porous structure and with an iso-oriented crystal structure. When Li-ions are utilized, the material can be charged and discharged in 20 seconds while still achieving a specific capacity of 140 mAh g−1. Moreover, the nanoscale architecture of mesoporous MoS2 retains this level of lithium capacity for 10 000 cycles. A detailed electrochemical kinetic analysis indicates that energy storage for both ions in MoS2 is due to a pseudocapacitive mechanism.
363 citations
TL;DR: In this article, a mesoporous molybdenum oxide (MoO3-x) with nanosized crystalline walls using a soft template (PEO-b-PS) synthesis method is introduced.
Abstract: A unique approach for the synthesis of nonstoichiometric, mesoporous molybdenum oxide (MoO3–x) with nanosized crystalline walls by using a soft template (PEO-b-PS) synthesis method is introduced. The as-synthesized mesoporous MoO3–x is very active and stable (durability > 12 h) for the electrochemical hydrogen evolution reaction (HER) under both acidic and alkaline conditions. The intrinsic MoO3 serves as an HER electrocatalyst without the assistance of carbon materials, noble metals, or MoS2 materials. The results from transmission electron microscopy and N2 sorption techniques show that the as-synthesized mesoporous MoO3–x has large accessible pores (20–40 nm), which are able to facilitate mass transport and charge transfer during HER. In terms of X-ray diffraction, X-ray photoelectron spectroscopy, temperature-programmed oxidation, and diffusive reflectance UV–vis spectroscopy, the mesoporous MoO3–x exhibits mixed oxidation states (Mo5+, Mo6+) and an oxygen-deficient structure. The as-synthesized MoO3–x only requires a low overpotential (≈0.14 V) to achieve a 10 mA cm−2 current density in 0.1 m KOH and the Tafel slope is as low as 56 mV dec−1. Density functional theory calculations demonstrate a change of electronic structure and the possible reaction pathway of HER. Oxygen vacancies and mesoporosity serve as key factors for excellent performance.
336 citations
TL;DR: The field of mesoporous metal nanoarchitectonics offers several advantages which cannot be found elsewhere, and various metal can now be synthesized as dendritic, core@shell, hollow or polyhedral nanoparticles, with single- or multicomponents, alloyed or not, with unprecedented electrochemical activity.
Abstract: The field of mesoporous metal nanoarchitectonics offers several advantages which cannot be found elsewhere. These materials have been showcasing impressive enhancements of their electrochemical properties for further implementation, compared to their micro- and macroporous counterparts. Since the last few decades, various methods have been developed to achieve narrow pore size distribution with a tunable porosity and particle morphology. While hard templates offer a reliable and intuitive approach to synthesize mesoporous metals, the complexity of the technique and the use of harmful chemicals pushed several research groups to focus in other directions. For example, soft templates (e.g., lyotropic crystals, micelles assemblies) and solution phase methods (requiring to control reduction reactions) offer more and more possibilities in terms of available compositions and morphologies. Indeed, various metal (Pt, Pd, Au, Ru, etc.) can now be synthesized as dendritic, core@shell, hollow or polyhedral nanoparticles, with single- or multicomponents, alloyed or not, with unprecedented electrochemical activity.
TL;DR: A novel in situ replication and polymerization strategy is developed for the synthesis of Fe-N-doped mesoporous carbon microspheres (Fe-NMCSs), which show a much better electrocatalytic performance in terms of higher catalytic activity, selectivity, and durability for the oxygen reduction reaction.
Abstract: A novel in situ replication and polymerization strategy is developed for the synthesis of Fe-N-doped mesoporous carbon microspheres (Fe-NMCSs). This material benefits from the synergy between the high catalytic activity of Fe-N-C and the fast mass transport of the mesoporous microsphere structure. Compared to commercial Pt/C catalysts, the Fe-NMCSs show a much better electrocatalytic performance in terms of higher catalytic activity, selectivity, and durability for the oxygen reduction reaction.
TL;DR: In this paper, a sensitive and selective colorimetric method for simultaneous detection and removal of copper (Cu(II)) ion from contaminated water samples was developed based on the functional ligand embedded mesoporous conjugate materials.
TL;DR: In this article, a mesoporous adsorbent was designed for high cesium (Cs) adsorption from wastewater based on large ring size of dibenzo-30-crown-10-ether (DB30C10) immobilized mesoporus.
TL;DR: For the first time, a nerve agent detoxifying enzyme, organophosphorus acid anhydrolase (OPAA), has been successfully encapsulated into a water-stable zirconium metal-organic framework (MOF), which features a hierarchical mesoporous channel structure and exhibits a 12 wt % loading capacity.
Abstract: Immobilized enzymes typically have greater thermal and operational stability than their soluble form. Here we report that for the first time, a nerve agent detoxifying enzyme, organophosphorus acid anhydrolase (OPAA), has been successfully encapsulated into a water-stable zirconium metal–organic framework (MOF). This MOF features a hierarchical mesoporous channel structure and exhibits a 12 wt % loading capacity of OPAA. The thermal and long-term stabilities of OPAA are both significantly enhanced after immobilization.
TL;DR: Mesoporous soft carbon (MSC) as discussed by the authors was prepared from mesophase pitch using nano-CaCO3 as the template, and the crystalline structure of soft carbon consists of a disordered region with a large interlayer distance benefitting sodium ion insertion/extraction and a graphitic region with good electrical conductivity.
Abstract: Mesoporous soft carbon (MSC) was prepared from mesophase pitch using nano-CaCO3 as the template. The crystalline structure of soft carbon consists of a disordered region with a large interlayer distance benefitting sodium ion insertion/extraction and a graphitic region with good electrical conductivity favoring high rate performance. Additionally, the mesoporous structure not only shortens the path of ion diffusion but also facilitates the penetration of non-aqueous electrolytes, which can further enhance the electrochemical performance of MSC. Benefiting from its unique microstructure, the MSC delivers a reversible capacity of 331 mA h g−1 at 30 mA g−1, and retains a capacity of 103 mA h g−1 at 500 mA g−1 after 3000 cycles, indicating its excellent rate capability and cycling performance. Therefore, soft carbon with appropriate structure is expected to be another choice for anode materials of sodium ion batteries.
TL;DR: The synthesis and characterization of a highly porous 3D COF with a record low density containing π-electron conjugated dehydrobenzoannulene units and metalation of DBA-3D-COF 1 with Ni results in a minimal reduction in the surface area.
Abstract: Constructing metalated three-dimensional (3D) covalent organic frameworks is a challenging synthetic task. Herein, we report the synthesis and characterization of a highly porous (SABET = 5083 m2 g–1) 3D COF with a record low density (0.13 g cm–3) containing π-electron conjugated dehydrobenzoannulene (DBA) units. Metalation of DBA-3D-COF 1 with Ni to produce Ni-DBA-3D-COF results in a minimal reduction in the surface area (SABET = 4763 m2 g–1) of the material due to the incorporation of the metal within the cavity of the DBA units, and retention of crystallinity. Both 3D DBA-COFs also display great uptake capacities for ethane and ethylene gas.
TL;DR: A simple emulsion-induced interface anisotropic assembly approach is reported to synthesize bowl-like mesoporous polydopamine particles with diameter of ∼210 nm, well-controlled radially oriented mesochannels, and large pore size of ∼11 nm, which manifest enhanced electrocatalytic performance for oxygen reduction reaction in alkaline electrolyte.
Abstract: Mesoporous colloidal particles with tailored asymmetric morphologies and radially oriented large channels are of great importance for development of new carriers for nanoencapsulation, high-performance mass transport nanosystems, and complex assembly structures. However, controllable anisotropic growth to asymmetric mesoporous particles is very challenging via the universal surfactant-directed soft-templating method. Herein we report a simple emulsion-induced interface anisotropic assembly approach to synthesize bowl-like mesoporous polydopamine particles with diameter of ∼210 nm, well-controlled radially oriented mesochannels, and large pore size of ∼11 nm. This interface-driven approach also creates opportunities for tailoring the assembly and formation of various asymmetric and symmetric polydopamine particles. Bowl-like mesoporous carbon particles with radially oriented channels, high accessible surface area of 619 m2 g–1, and large pore size of ∼8 nm can be fabricated by subsequent hydrothermal treat...
TL;DR: NU-1000 has been reported as an excellent candidate for the separation of gases, and it is a versatile scaffold for heterogeneous catalysis, which shows great promise as a new generic platform for a wide range of applications.
Abstract: The synthesis of NU-1000, a highly robust mesoporous (containing pores >2 nm) metal-organic framework (MOF), can be conducted efficiently on a multigram scale from inexpensive starting materials. Tetrabromopyrene and (4-(ethoxycarbonyl)phenyl)boronic acid can easily be coupled to prepare the requisite organic strut with four metal-binding sites in the form of four carboxylic acids, while zirconyl chloride octahydrate is used as a precursor for the well-defined metal oxide clusters. NU-1000 has been reported as an excellent candidate for the separation of gases, and it is a versatile scaffold for heterogeneous catalysis. In particular, it is ideal for the catalytic deactivation of nerve agents, and it shows great promise as a new generic platform for a wide range of applications. Multiple post-synthetic modification protocols have been developed using NU-1000 as the parent material, making it a potentially useful scaffold for several catalytic applications. The procedure for the preparation of NU-1000 can be scaled up reliably, and it is suitable for the production of 50 g of the tetracarboxylic acid containing organic linker and 200 mg-2.5 g of NU-1000. The entire synthesis is performed without purification by column chromatography and can be completed within 10 d.
TL;DR: In this article, a mesoporous hybrid adsorbent (MHA) was developed for selective cesium removal from contaminated water using direct immobilization approach and serving as an efficient adsorent for Cs removal.
TL;DR: A nanostructured version of the well-known cathode material, LiMn2O4, reduced by about half, but both charge and discharge kinetics as well as cycling stability were improved significantly andKinetic analysis of the redox reactions was used to verify the pseudocapacitive mechanisms of charge storage and establish the feasibility of using nanoporous LixMn 2O4 as a cathode in lithium-ion devices based on pseudocapsitive charge storage.
Abstract: Charge storage devices with high energy density and enhanced rate capabilities are highly sought after in today's mobile world. Although several high-rate pseudocapacitive anode materials have been reported, cathode materials operating in a high potential range versus lithium metal are much less common. Here, we present a nanostructured version of the well-known cathode material, LiMn2O4. The reduction in lithium-ion diffusion lengths and improvement in rate capabilities is realized through a combination of nanocrystallinity and the formation of a 3-D porous framework. Materials were fabricated from nanoporous Mn3O4 films made by block copolymer templating of preformed nanocrystals. The nanoporous Mn3O4 was then converted via solid-state reaction with LiOH to nanoporous LixMn2O4 (1 < x < 2). The resulting films had a wall thickness of ∼15 nm, which is small enough to be impacted by inactive surface sites. As a consequence, capacity was reduced by about half compared to bulk LiMn2O4, but both charge and discharge kinetics as well as cycling stability were improved significantly. Kinetic analysis of the redox reactions was used to verify the pseudocapacitive mechanisms of charge storage and establish the feasibility of using nanoporous LixMn2O4 as a cathode in lithium-ion devices based on pseudocapacitive charge storage.
TL;DR: These P-C3N4/ZnIn2S4 nanocomposites have been proven to be highly efficient visible light responsive photocatalysts for photo-reduction, and meanwhile exhibit excellent photo-stability during recycling runs.
Abstract: In this report, we rationally designed and fabricated P-C3N4/ZnIn2S4 nanocomposites by in situ immobilizing ZnIn2S4 nanosheets onto the surface of mesoporous P-doped graphite carbon nitrogen (P-C3N4) nanosheets in a mixed solvothermal environment; their application to the photoreduction of 4-nitroaniline was used to estimate the photocatalytic performance. Different to the template route, here the mesoporous P-C3N4 nanosheets were prepared with a template-free strategy. The as-fabricated P-C3N4/ZnIn2S4 nanocomposites were systematically characterized by analyzing the phase structure, chemical components, electronic and optical properties and separation of charge carrier pairs. More importantly, these P-C3N4/ZnIn2S4 heterostructures have been proven to be highly efficient visible light responsive photocatalysts for photo-reduction, and meanwhile exhibit excellent photo-stability during recycling runs. The sufficient evidence reveals that the significantly improved photocatalytic performance is mainly attributed to the more efficient charge carrier separation based on the construction of a close heterogeneous interface. This work may provide new insights into the utilization of P-C3N4/ZnIn2S4 nanocomposites as visible light driven photocatalysts for comprehensive organic transformations in the field of fine chemical engineering.
TL;DR: This review article provides a comprehensive overview of the controlled synthesis of PMO NPs and organo-bridged MSNs, physicochemical and biocompatible properties, and their nano-biomedical application as bioimaging agent and/or therapeutic agent delivery system.
TL;DR: In this paper, the synthesis of Ag-doped ordered mesoporous tin(IV) oxide-titanium oxide nanohybrids using a sequential combination of a wet impregnation and nanocasting process is presented.
Abstract: Hybrid mesoporous metal oxides show promising attributes in the field of relative gas sensors due to the combined opportunities provided by the high specific surface area and framework components. In this study, we present the synthesis of Ag-doped ordered mesoporous tin(IV) oxide–titanium(IV) oxide nanohybrids using a sequential combination of a wet impregnation and nanocasting process and demonstrate the response by exposing the mesoporous nanohybrids to ethanol gas. HRTEM and N2 adsorption–desorption results indicate that the nanohybrids prepared by nanocasting of SBA-15 as the hard template possess an ordered mesoporous structure and high surface area. It was also observed that the mesoporous Ag-(TiO2/SnO2) shows excellent response towards ethanol with concentrations ranging from 1 ppm to 500 ppm. Besides, the nanohybrid mesoporous sensor shows high selectivity towards other volatile organic compounds (VOCs) including acetone, methanol, isopropanol, benzyl alcohol and ethyl acetate. All the results indicated that the nanocast mesoporous Ag-(TiO2/SnO2) nanohybrids have great potential for applications in designing high performance practical ethanol sensors.
TL;DR: These results demonstrate that azolate MOFs are sufficiently thermally and chemically stable to find uses in recyclable sorption, storage, and potentially separation of chemically challenging and/or corrosive gases, especially when designed to exhibit a high density of open metal sites.
Abstract: A series of new mesoporous metal–organic frameworks (MOFs) made from extended bisbenzenetriazolate linkers exhibit coordinatively unsaturated metal sites that are responsible for high and reversible uptake of ammonia. Isostructural Mn, Co, and Ni materials adsorb 15.47, 12.00, and 12.02 mmol of NH3/g, respectively, at STP. Importantly, these near-record capacities are reversible for at least three cycles. These results demonstrate that azolate MOFs are sufficiently thermally and chemically stable to find uses in recyclable sorption, storage, and potentially separation of chemically challenging and/or corrosive gases, especially when designed to exhibit a high density of open metal sites.
TL;DR: Results suggest that the novel Cu-MSNs could be used as an immunomodulatory agent with osteostimulatory capacity for bone regeneration/therapy application and introduces controllable amount of therapeutic ions instead of loading expensive drugs/growth factors in mesoporous silica nanosphere.
TL;DR: In this article, a review of the most recent progress in the design of zeolite-containing metal nanoparticles is presented, which differ from traditional materials by the originality of the synthesis method or the morphology of the support.
Abstract: Microporous cavities and channels of zeolites frameworks have been used for decades for the encapsulation of cations, complexes and metals. In the particular case of metals, nanoparticles are usually formed after post-synthesis modifications such as ion-exchange or wetness impregnation. Tough encapsulation can provide a strict control of the nanoparticle size as well as a limitation of aggregation at high temperature; encapsulated nanoparticles are often hardly accessible due to diffusion limitations of reactants in sub-nanometric micropores. Recent developments in zeolite synthesis have offered a new class of materials with hierarchical structures or unusual morphologies in which the mean diffusion path is considerably reduced. Those zeolites with inter-crystalline and/or intra-crystalline mesopore systems are particularly adapted for supporting nanoparticles both in microporous cavities of the framework and in mesoporous channels. More sophisticated architectures such as yolk/core–shell materials, in which nanoparticles are protected against poisoning or sintering by a thin zeolite shell, are particularly attractive. In contrast to nanometric intrinsic cavities of zeolite frameworks, a large internal void is available for chemical reactions and such catalysts can be considered as nanoreactors in which the reaction is essentially governed by the permeability of the shell. This review focuses on the most recent progress as well as perspectives in the design of zeolite-containing metal nanoparticles, which differ from traditional materials by the originality of the synthesis method or the morphology of the support.
TL;DR: In this article, a dual-porous metal organic framework (MOF) was employed in CO2 fixation at room temperature using a micro-mesoporous MOF, UMCM-1-NH2, in the synthesis of various five-membered cyclic carbonates.
TL;DR: The synthesis of phenolic azo-polymers with hierarchical porous structures based on diazo-coupling reaction in aqueous solution under mild conditions is reported, with excellent performance for catalyzing the reaction of CO2 with epoxide and the oxidation of alcohol.
Abstract: The synthesis of hierarchically mesoporous polymers with multiple functionalities is challenging. Herein we reported a template-free strategy for synthesis of phenolic azo-polymers with hierarchical porous structures based on diazo-coupling reaction in aqueous solution under mild conditions. The resultant polymers have surface areas up to 593 m2 g−1 with the mesopore ratio of >80 %, and a good ability to complex with metal ions, such as Cu2+, Zn2+,Ni2+, achieving a metal loading up to 26.24 wt %. Moreover, the polymers complexed with Zn showed excellent performance for catalyzing the reaction of CO2 with epoxide, affording a TOF of 2570 h−1 in the presence of tetrabutyl ammonium bromide (7.2 mol %). The polymer complexed with Cu could catalyze the oxidation of alcohol with high efficiency.
TL;DR: The stability of Mo-SIM was further confirmed computationally, with density functional theory calculations indicating that the dissociation of the molybdenum(VI) species from the node of NU-1000 is endergonic, corroborating the experimental data for the Mo- SIM material.
Abstract: Molybdenum(VI) oxide was deposited on the Zr6 node of the mesoporous metal–organic framework NU-1000 via condensed-phase deposition where the MOF is simply submerged in the precursor solution, a process named solvothermal deposition in MOFs (SIM). Exposure to oxygen leads to a monodisperse, porous heterogeneous catalyst, named Mo-SIM, and its structure on the node was elucidated both computationally and spectroscopically. The catalytic activity of Mo-SIM was tested for the epoxidation of cyclohexene. Near-quantitative yields of cyclohexene oxide and the ring-opened 1,2-cyclohexanediol were observed, indicating activity significantly higher than that of molybdenum(VI) oxide powder and comparable to that of a zirconia-supported analogue (Mo-ZrO2) prepared in a similar fashion. Despite the well-known leaching problem of supported molybdenum catalysts (i.e., loss of Mo species thus causes deactivation), Mo-SIM demonstrated no loss in the metal loading before and after catalysis, and no molybdenum was detected...