Large-sized Mesopores Research Articles

Research on double template agents to regulate the grain growth behavior of SAPO-34

The effects of different template ratios on the physicochemical properties of SAPO-34 molecular sieve and the catalytic performance of methanol to olefin (MTO) were investigated using tetraethylammonium hydroxide (TEAOH) and morpholine (Mor) as mixed templates. It was found that when the amount of Mor was more, the grains were smooth and regular cubes, and the acidity was stronger, and the mesoporous content was more. With the increase of TEAOH, the grain surface gradually changed into a multi-grain stacking structure, the acidity decreased slightly, and the large-sized mesopores slowly disappeared, replaced by small-sized mesopores with a diameter of 3–4 nm. It can be seen from the MTO reaction that the molecular sieve with stronger acidity deactivates faster, and the mesoporous size is too large to affect the shape-selective catalytic ability of the catalyst, which is not conducive to the formation of light olefins. Combined with the reaction and characterization, when the template ratio R = 4, the acidity distribution in the molecular sieve is moderate, and the average pore size is small, which improves the selectivity of low olefins.

Metal–organic framework-derived mesoporous rGO–ZnO composite nanofibers for enhanced isopropanol sensing properties

Metal–organic framework (MOF)-derived porous reduced graphene oxide (rGO)–ZnO composite nanofibers (NFs) were fabricated by using rGO and zeolitic imidazolate framework-8 (ZIF-8) as electrospun precursors. The prepared materials were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectrum (XPS), ultraviolet photoelectron spectroscopy (UPS), and the Brunauer–Emmet–Teller (BET) method, respectively. This innovative rGO–ZnO composite NFs integrated the advantages of two kinds of porous material (MOFs and NFs), thereby displayed high density and large-size mesopores. Sensing results indicated that the 3 mL rGO–ZnO NFs demonstrated good sensing properties characterized by higher isopropanol (IPA) sensing responses (2.8-fold improvement @ 50 ppm) and faster response/recovery times (14 s/39 s) in comparison with pure ZnO nanocages. In addition, good selectivity and stability towards IPA of the 3 mL rGO–ZnO NFs were also observed. High IPA sensing properties were attributed to the synergic coupling between rGO nanosheets and ZnO nanoparticles, as well as the unique MOF-derived 3D mesh nanofiber structure with large-size mesopores, high surface area, and anti-aggregation property. This study presents a new approach for constructing MOF-derived porous rGO–metal oxide composite mesh NFs sensing materials with high-performances.

Antioxidant, Enzyme, and H2O2-Triggered Melanoma Targeted Mesoporous Organo-Silica Nanocomposites for Synergistic Cancer Therapy.

The multi-stimuli responsive drug delivery system has recently attracted attention in cancer treatments, since it can reduce several side effects and enhance cancer therapeutic efficacy. Herein, we present the intracellular antioxidant (glutathione, GSH), enzyme (hyaluronidase, HAase), and hydrogen peroxide (H2O2) triggered mesoporous organo-silica (MOS) nanocomposites for multi-modal treatments via chemo-, photothermal, and photodynamic cancer therapies. A MOS nanoparticle was synthesized by two-types of precursors, tetraethyl orthosilicate (TEOS) and bis[3-(triethoxysilyl)propyl] tetrasulfide (BTES), providing large-sized mesopores and disulfide bonds cleavable by GSH. Additionally, we introduced a new β-cyclodextrin-hyaluronic acid (CDHA) gatekeeper system, enabling nanocomposites to form the specific interaction with the ferrocene (Fc) molecule, control the drug release by the HAase and H2O2 environment, as well as provide the targeting ability against the CD44-overexpressing melanoma (B16F10) cells. Indocyanine green (ICG) and doxorubicin (Dox) were loaded in the MOS-Fc-CDHA (ID@MOS-Fc-CDHA) nanocomposites, allowing for hyperthermia and cytotoxic reactive oxygen species (ROS) under an 808 nm NIR laser irradiation. Therefore, we demonstrated that the ID@MOS-Fc-CDHA nanocomposites were internalized to the B16F10 cells via the CD44 receptor-mediated endocytosis, showing the controlled drug release by GSH, HAase, and H2O2 to enhance the cancer therapeutic efficacy via the synergistic chemo-, photothermal, and photodynamic therapy effect.

Zr-MOFs Integrated with a Guest Capturer and a Photosensitizer for the Simultaneous Adsorption and Degradation of 4-Chlorophenol.

A bifunctional metal-organic framework (MOF) was successfully designed to realize the purification of 4-chlorophenol (4-CP) under simulated sunlight irradiation. Owing to the large-size mesopores of the MOF matrix NU-1000, β-CMCD (carboxylic β-cyclodextrin) could be incorporated into the frameworks with a density of 2.4% to pre-enrich the pollutant of 4-CP. Meanwhile, the photodegradation promoter [Pd(II) meso-tetra(4-carboxyphenyl)porphine] was in situ co-assembled with the organic ligand to realize its synchronous degradation. As for the current integrator, a Langmuir model was used to explain the adsorption isotherm, and the Langmuir-Hinshelwood model exhibited a better fit to its catalytic degradation behavior. Thanks to the simultaneous presence of a capturer and a photodegradation promoter, the adsorption capacity of 4-CP reached as high as 296 mg g-1, which was further completely detoxified within 60 min under simulated sunlight irradiation with a half-life time of only 5.98 min. Such excellent integrated decontamination properties prefigure the great promising potential of multifunctional MOFs in the field of pollution purification.

Porosity and composition of nitrogen-doped carbon materials templated by the thermolysis products of calcium tartrate and their performance in electrochemical capacitors

Porous nitrogen-doped carbon materials were synthesized by chemical vapor deposition method using template nanoparticles produced by the decomposition of calcium tartrate in thermal shock conditions. The synthesis temperature was varied from 650° to 900°C with a step of 50 °C and acetonitrile vapor was supplied into reactor immediately after the template formation. Transmission electron microscopy and X-ray diffraction analysis detected an increase of the number of ordered graphitic layers with the rise of the synthesis temperature. That was accompanied by a decrease of the specific surface area and the total pore volume determined from N2 adsorption measurements. Higher surface area of the materials produced at 650 and 700 °C was assigned to the co-existence of CaCO3 and CaO template nanoparticles at these temperatures. X-ray photoelectron spectroscopy found about 4–5 at% of nitrogen in all materials and a strong temperature-dependence of the ratio of nitrogen forms. The material synthesized at 750 °C showed the best electrochemical performance in 1 M H2SO4 electrolyte due to the presence of large fraction of pyridinic nitrogen responsible for pseudo-capacitance, graphitic nitrogen promoting charge transport, and large-size mesopores providing the fast diffusion of electrolyte ions.

Improved Rectification and Osmotic Power in Polyelectrolyte-Filled Mesopores.

Ample studies have shown the use of nanofluidics in the ionic diode and osmotic power generation, but similar ionic devices performed with large-sized mesopores are still poorly understood. In this study, we model and realize the mesoscale ionic diode and osmotic power generator, composed of an asymmetric cone-shaped mesopore with its narrow opening filled with a polyelectrolyte (PE) layer with high space charges. We show that, only when the space charge density of a PE layer is sufficiently large (>), the considered mesopore system is able to create an asymmetric ionic distributions in the pore and then rectify ionic current. As a result, the output osmotic power performance can be improved when the filled PE carries sufficiently high space charges. For example, the considered PE-filled mesopore system can show an amplification of the osmotic power of up to 35.1-fold, compared to the bare solid-state mesopore. The findings provide necessary information for the development of large-sized ionic diode and osmotic power harvesting device.

Development of intracrystalline mesoporosity in NH4HF2-etched NaY zeolites by surfactant-templating and its effect on toluene adsorption

Volatile organic compounds have seriously affected the natural environment and human health, and adsorption is one of the most effective method for controlling VOCs pollution. In this work, the NH4HF2-etched NaY-s-x zeolites with intracrystalline mesoporosity are obtained via the surfactant-templating process in weak base NH4OH solution. The morphology, microstructure, and toluene adsorption property of as-prepared hierarchical Y zeolites are systematically characterized. It is found that the structural and textural properties of NH4HF2-etched NaY samples are significantly changed by the simple surfactant-templated approach and the large-sized mesopores inside NH4HF2-etched NaY sample disappear to form the surfactant-templated mesoporosity with a size of ~4 nm. It is demonstrated that the intracrystalline mesoporosity obviously improves the toluene molecular adsorption properties of zeolite samples. Moreover, the mechanism of the surfactant-templating process is elucidated.

Manganese oxide(Ⅲ)/carbon hybrids with interesting morphologies as improved active materials for supercapacitors

Abstract Mn2O3/C hybrids with almond-like, peach-like and peanut-like morphologies are fabricated via hydrothermal method followed by annealing in air at ambient pressure. Their physical properties and morphologies are characterized by X-ray diffraction (XRD), Raman scattering spectroscopy (Raman), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM). Almond-like Mn2O3/C (Mn2O3/C-ALL) and peach-like Mn2O3/C (Mn2O3/C-PCL) hybrids are highly porous with large-sized mesopores. In contrast, peanut-like Mn2O3/C (Mn2O3/C-PNL) is composed of densely packed slender nanofibers. The results show Mn2O3 and carbon have homogeneous contact accounting for high conductivity. In 1.0 M Na2SO4 aqueous electrolyte, Mn2O3/C-PCL has the highest specific capacitance of 158.8 F g−1 at 1.0 A g−1, compared to Mn2O3/C-ALL (105.1 F g−1) and Mn2O3/C-PNL (77.5 F g−1). Furthermore, the capacitance retention of Mn2O3/C-PCL achieves 48.8% upon a 50-fold increase in current density. Finally, the Mn2O3/C-PCL displays an impressive long-term cycle stability of 90.6% specific capacitance retention after 10,000 cycles at 1.0 A g−1. Therefore, this work highlights the importance of morphology in Mn2O3/C hybrids design to obtain high performance supercapacitor materials.

Water Sorption Property Controlled by Nanoscale Pore Connectivity of Large-Sized Cage-Type Mesopores

Water sorption property over silicate surfaces is designed by a reasonable method to control the distance of large-sized cage-type mesopores and their connectivity through small mesoporous windows that can be fabricated using a polystyrene-block-polybutadiene-block-polystyrene triblock copolymer functionalized with hydrophilic sulfonic groups.

A new Cu-anchored mesoporous organosilica material for facile C–S coupling reactions under microwave irradiation

We report a new ordered Cu-anchored 2D-hexagonal mesoporous imine functionalized organosilica material Cu-MPIOS. This Cu-anchored mesoporous material has been synthesized via post synthetic functionalization of SBA-15 with 3-(2-aminoethylamino)propyl-dimethoxymethylsilane followed by Schiff-base condensation with 2-thiophene carboxaldehyde. Cu(I) has been grafted finally over Schiff-base functionalized mesoporous material through chemical impregnation to obtain Cu-MPIOS. The materials are characterized thoroughly using various techniques like powder X-ray diffraction, N2 adsorption/desorption analysis, FTIR, UV–vis spectroscopy, FEG-TEM, FE-SEM, 13C cross-polarization magic angle spinning NMR, TGA/DTA, EPR, AAS and CHN chemical analysis. High Brunauer–Emmett–Teller (BET) surface area and the presence of very large size mesopores (8.1nm) in Cu-MPIOS has motivated us to explore its catalytic activity in one-pot three-component C–S cross coupling reaction by varying different aryl halides in the aqueous medium under microwave assisted heating conditions. This heterogeneous Cu-catalyst shows high catalytic performance as well as good recycling efficiency in this C–S coupling reaction, suggesting its future potential for the synthesis of value added thioether derivatives.

Hierarchical porous carbon derived from rice husk as a low-cost counter electrode of dye-sensitized solar cells

The porous carbon with a high surface area is prepared from rice husk through pyrolysis and chemical activation and explored as the counter electrode of dye-sensitized solar cells. Structure and texture analysis reveals that the as-prepared porous carbon has a hierarchical porous structure containing large-size mesopores and abundant micropores. Electrochemical studies indicate that the obtained hierarchical porous carbon electrode has high electrocatalytic activity for I−/I3− redox reaction and enhanced electrolyte diffusion capability. These enhanced electrochemical properties are beneficial for improving the photovoltaic performance of dye-sensitized solar cells. Under irradiation of 100 mW cm−2, the dye-sensitized solar cell with this porous carbon counter electrode shows a conversion efficiency of 6.32%, which is closed to that of the cell with Pt electrode (6.69%). These promising results highlight the potential application of hierarchical porous carbon derived from rice husk in more cost-effective dye-sensitized solar cells.

Electrochemical Preparation of Controllably Large-sized Mesoporous Platinum Films by Using Diblock Copolymers and an Organic Expander

Abstract Mesoporous Pt films with controllably large-sized mesopores were prepared by using a diblock copolymer (polystyrene-b-poly(ethylene oxide), PS-b-PEO) and an organic expander (polystyrene homopolymer, h-PS). With the increase in the molecular weight of PS-b-PEO, the mesopore size gradually increased. All films possess spherical cage-type mesopores irrespectively of both the molecular weight of PS-b-PEO and the use of the expander.

Close-packed mesoporous carbon polyhedrons derived from colloidal carbon microspheres for electrochemical energy storage applications

A new class of mesoporous carbon polyhedrons (MCPs) with a facet-to-facet close-packed model are presented for the first time as electrode materials for electrochemical capacitors (ECs). These MCPs are evolved directly from the colloidal carbon microspheres (CCMs) by a new silica-free approach, the top-down carbonate (Li2CO3) site-occupying strategy. The obtained polyhedral materials consist of a desirable mesoporous structure with mesopores with a mean size of about 30 nm. The unique structures of the large-size mesopores in a close-packed combination are considered to provide a more favourable pathway for electrolyte penetration and transportation, as well as good electronic conductivity for electrochemical energy storage applications. Accordingly, the resultant mesoporous materials show great promise for high performance EC applications, of which high energy and high power properties are desirable.

Structural evolution of hierarchically macro/mesoporous Al2O3 monoliths under heat-treatment

Hierarchically macro/mesoporous alumina monoliths were successfully fabricated from a facile sol–gel process by introducing PEG8000 to the reaction solution of ordered mesoporous Al2O3 (OMA, P123/isopropoxide aluminum/HNO3). The monolithic gels were subsequently calcined at different temperatures to investigate the morphological evolution. Monolithic skeletons were obtained in the dried gels with bimodal close-celled macropores. The bimodal macroporous structure is preserved after calcination at 450°C. The macropores are interconnected with large-sized mesopores, which facilitates the monolith with high surface area of 286.9m2/g and pore volume of 0.67cm3/g. This hierarchical feature persists up to 1100°C after phase-transformation from γ-Al2O3 to α-Al2O3 with the shrinkage of macropores and expansion of mesopores.

Facile Synthesis of Hierarchical Alumina Monoliths with Tubular Macropores and Ordered Mesoporous Walls

Abstract A facile approach of evaporation-induced self-assembly plus coating was developed using nonwoven fabrics (NF) as a sacrificial scaffold, leading to the acquisition of hierarchically macro/mesoporous alumina monolith. The macropores templated by NF show a tubular structure of about 10 µm in channel diameter. The monolith is composed of ordered mesostructured wall with large-sized mesopores and high thermal stability. The regularity of the mesopores can be maintained up to 900 °C, even after the amorphous Al2O3 transforms to crystalline structure (γ-Al2O3). This facile route can be extended to the preparation of other hierarchically macro/mesoporous monoliths such as TiO2, ZrO2, ZnO, et al.

Polymerase‐Functionalized Hierarchical Mesoporous Titania Thin Films: Towards a Nanoreactor Platform for DNA Amplification

Titania thin films with hierarchical nanopore architecture are efficient hosts for Taq polymerase, which is selectively located in large-size mesopores. These biofunctional nanomaterials, highly tuned on the biomolecular length scale, are able to efficiently amplify DNA in a polymerase chain reaction. The engineered pore sizes and interconnectivity at the nanoscale are the key to bio-functionalization and enzyme performance.

Synthesis of Novel Structured TiO2 with Mesopores by Anodic Oxidation

In this study, a simple anodic oxidation process resulted in the successful synthesis of novel N-ion-doped TiO(2) with one-dimensionally aligned and large-sized mesopores. TiO(2) obtained by this anodic oxidation process possessed the high values of specific surface area and a large amount of one-dimensional mesopores with 30-50 nm diameter. Furthermore, X-ray photoelectron spectroscopy and UV-vis results suggested the possibility that these TiO(2) products were composed of a N-ion-doped powder. Thus, novel structured TiO(2) with large-sized mesopores was simply synthesized by an anodic oxidation of Ti metal in a nitric acid solution. These uniquely nanostructured mesoporous TiO(2) products will expand possibilities for applying mesoporous TiO(2) in new fields.

CO 2-reforming of methane over Ni/SiO 2 catalyst prepared by homogeneous precipitation in sol–gel-derived silica gel

Ni/SiO 2 catalysts with Ni content up to 50 wt.% were prepared by depositing nickel hydroxides in a sol–gel-derived wet silica gel, where nickel hydroxides were produced by the increase in pH due to the decomposition of urea. The Ni dispersion in the resulting catalysts is relatively high, and increases monotonically with increasing Ni content up to 40 wt.%. The Ni/SiO 2 catalysts have large volume and large-sized mesopores at ≤20 wt.% Ni-loading, and have high thermal stability. In the CO 2-reforming of methane, the catalytic activity proportionally increases with increasing Ni content at reaction temperatures between 500 and 900 °C. High and steady catalytic activity is achieved when we use the Ni/SiO 2 catalysts with Ni content of 20 wt.% under the reaction conditions of high space-time velocity and high temperature.