Mesoporous Research Articles

Refining the Distinct Cu-N4 Coordination in Mesoporous N-Doped Carbon to Boost Selective Deuteration under Mild Conditions.

Deuterated compounds have broad applications across various fields, with dehalogenative deuteration serving as an efficient method to obtain these molecules. However, the diverse electronic structures of active sites in the heterogeneous system and the limited recyclability in the homogeneous system significantly hinder the advancement of dehalogenative deuteration. In this study, we present a catalyst composed of copper single-atom sites anchored within an ordered mesoporous nitrogen-doped carbon matrix, synthesized via a mesopore confinement method. The Cu1/OMNC-1100 catalyst, characterized by Cu-N4 sites, demonstrates exceptional performance, high functional group tolerance, and remarkable durability in the deuteration of 2-bromo-6-methoxynaphthalene under relatively mild conditions (80 °C, 2 MPa of CO). Experimental results combined with X-ray absorption fine structure analysis reveal that Cu-N3 sites can be converted into more stable Cu-N4 counterparts at higher pyrolysis temperatures, resulting in enhanced catalytic activity. This work demonstrates a strategy for designing single-atom site catalysts with tunable coordination environments, providing a promising approach to improving catalytic performance in selective dehalogenative reactions under relatively mild conditions.

In Situ Synthesis of Zr-Doped Mesoporous Silica Based on Zr-Containing Silica Residue and Its High Adsorption Efficiency for Methylene Blue

Zr-containing silica residue (ZSR) is an industrial by-product of ZrOCl2 production obtained through an alkali fusion process using zircon sand. In this study, low-cost and efficient Zr-doped mesoporous silica adsorption materials (Zr-MCM-41 and Zr-SBA-15) were prepared in one step via the hydrothermal synthesis method using ZSR as the silicon source for the removal of methylene blue (MB) from dye-contaminated wastewater. The samples were characterized using X-ray fluorescence (XRF) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetry (TG), and N2 adsorption–desorption measurements. The findings indicate that the synthesized Zr-MCM-41 and Zr-SBA-15 possess highly ordered mesoscopic structures with high specific surface areas of 910 and 846 m2/g, large pore volumes of 1.098 and 1.154 cm3/g, and average pore diameters of 4.18 and 5.35 nm, respectively. The results of the adsorption experiments show that the adsorbent has better adsorption properties under alkaline conditions. The adsorption process obeys the pseudo-quadratic kinetic model and the Freundlich adsorption isotherm model, indicating the coexistence of physical and chemisorption processes. The maximum adsorption capacities of Zr-MCM-41 and Zr-SBA-15 are 618.43 and 516.58 mg/g, respectively, as calculated by the Langmuir model (pH = 9, temperature of 25 °C). Compared with mesoporous silica prepared with sodium silicate as the silicon source, Zr-MCM-41 and Zr-SBA-15 have different structural properties and better adsorption properties due to Zr doping. These findings indicate that ZSR is the preferred silicon source for preparing mesoporous silica, and the mesoporous silica prepared using Zr silicon slag is a promising adsorbent and has great application potential in wastewater treatment.

Efficient adsorptive removal of Congo Red dye using activated carbon derived from Spathodea campanulata flowers

This report investigates the preparation, characterization, and application of activated carbon derived from Spathodea campanulata flowers (SCAC) to remove Congo Red (CR) dye from aqueous streams. SCAC was synthesized using orthophosphoric acid activation which yielded a mesoporous material with a specific surface area of (986.41 m2/g), significantly exceeding values reported for flower-derived activated carbons in the available literature. Field emission scanning electron microscopy (FESEM) image revealed an irregular, rough surface morphology pre-adsorption, which became smoother post-adsorption, indicating successful CR attachment. Elemental analysis through energy-dispersive x-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) confirmed an increase in carbon content and the appearance of sulfur, verifying CR uptake. Adsorption kinetics obeyed the pseudo-second-order equation, signifying chemisorption, while the equilibrium dataset fitted better to the Langmuir model, with R2 of 0.9944, suggesting a monolayer adsorption mechanism with a maximum adsorption capacity of 59.27 mg/g. Thermodynamic analysis revealed spontaneous and endothermic adsorption process. Desorption studies showed methanol as the most effective desorbing agent, with SCAC retaining considerable adsorption capacity across six cycles, highlighting its reusability. In tests with real water matrices, SCAC demonstrated significantly higher removal efficiency in natural waters than control, suggesting enhanced adsorption in complex matrices. These findings underscore the practical applicability of SCAC in real-world wastewater treatment, offering a promising solution for large-scale industrial applications.

Mesoporous materials 2.0: innovations in metals and chalcogenides for future applications

Abstract Incorporating mesoporous structures into various materials can provide abundant active sites and facilitate smooth diffusion, and their effectiveness has been demonstrated across a range of material types. However, despite the development of numerous mesoporous materials, first-generation mesoporous materials (e.g., silica-based compositions) have limited applications due to their poor electrical conductivity and limited compositional diversity, necessitating additional processing for widespread utilization. Our group first proposed the synthesis of mesoporous metals using a solution-based soft-templating method based on self-assembly of micelles, marking a significant advancement in mesoporous materials. This effective process has recently been extended to the synthesis of mesoporous metals and chalcogenides. Chalcogenides have garnered significant attention due to their intriguing optical, electrical, and electrochemical properties arising from their distinctive electronic structures. Mesoporous chalcogenides have been found to effectively enhance these properties. This paper provides a comprehensive review of the synthesis of mesoporous metals and chalcogenides—representing second-generation mesoporous materials (mesoporous materials 2.0)—with specific examples. Our goal is to inform readers about second-generation mesoporous materials and provide insights for further research.

Exploring the crystallisation of aspirin in a confined porous material using solid-state nuclear magnetic resonance.

In this study, nuclear magnetic resonance (NMR) is used to investigate the crystallisation behaviour of aspirin within a mesoporous SBA-15 silica material. The potential of dynamic nuclear polarisation (DNP) experiments is also investigated using specifically designed porous materials that incorporate polarising agents within their walls. The formation of the metastable crystalline form II is observed when crystallisation occurs within the pores of the mesoporous structure. Conversely, bulk crystallisation yields the most stable form, namely form I, of aspirin. Remarkably, the metastable form II remains trapped within the pores of mesoporous SBA-15 silica material even 30 days after impregnation, underscoring its persistent stability within this confined environment.

Characterization of Alpha Mangostin Loaded-Mesoporous Silica Nanoparticle and the Impact on Dissolution and Physical Stability.

Improving drug solubility is crucial in formulating poorly water-soluble drugs, especially for oral administration. The incorporation of drugs into mesoporous silica nanoparticles (MSN) is widely used in the pharmaceutical industry to improve physical stability and solubility. Therefore, this study aimed to elucidate the mechanism of poorly water-soluble drugs within MSN, as well as evaluate the impact on the dissolution and physical stability. Alpha mangostin (AM) was adopted as a model of a poorly water-soluble drug, while MSN with the pore size of 45 Å (MSN45) and 120 Å (MSN120) were used as Mesoporous materials. AM-loaded MSN (AM/MSN45 and AM/MSN120) was prepared by solvent evaporation method. The amorphization of AM/MSN45 and AM/MSN120 was confirmed by the halo pattern observed in the powder X-ray diffraction pattern and the absence of the melting peak and the glass transition of AM in the DSC curves. This signified the successful incorporation of AM into MSN. FT-IR measurements suggested the formation of hydrogen bond interaction between the carbonyl group of AM and the silica surface of MSN. In the dissolution test, the presence of the AM within MSN improved the dissolution rate and generated the supersaturation of AM. However, the difference of pores size of MSN could affect the dissolution profile of AM within MSN. Additionally, it retained the X-ray halo patterns after 30 d of storage at 25 oC and 0% RH. In conclusion, AM-loaded mesoporous silica significantly improved the dissolution and physical stability.

Synthesis of chiral mesoporous silica nanoparticles for the adsorptive removal of chiral insecticide sulfoxaflor from water

Mesoporous materials have garnered a lot of interest because of their porous structure, larger surface area and easy surface functionalization to incorporate functional group of choice. Herein, chiral mesoporous silica...

Template Free Direct Approach to Crystalline Mesoporous ZnO/Bi2O3 Mixed Oxide Nanosheets with Enhanced Photo reactivity

Template Free Direct Approach to Crystalline Mesoporous ZnO/Bi₂O₃ Mixed Oxide Nanosheets with Enhanced Photo reactivity

A promising mesoporous silica carrier material for the diagnosis and treatment of liver diseases: recent research advances.

The therapeutic diagnosis of liver diseases has garnered significant interest within the medical community. In recent years, mesoporous silica nanoparticles (MSNs) have emerged as crucial nanocarriers for the treatment of liver ailments. Their remarkable diagnostic capabilities enable them to be used in techniques such as high-throughput mass spectrometry (MS), magnetic resonance imaging (MRI), near-infrared (NIR) fluorescence imaging, photoacoustic imaging (PAI), and ultrasonography (US), attracting considerable attention. Furthermore, the introduction of amino and carboxyl group modifications in MSNs has facilitated their use as drug delivery carriers for treating liver diseases, including hepatocellular carcinoma. This paper reviews the preparation methods, in vitro diagnostic capabilities, and in vivo therapeutic delivery systems of MSNs for liver disease treatment. It also summarizes relevant toxicity studies, aiming to provide a comprehensive overview of the diagnostic and therapeutic applications of MSNs in the treatment of liver diseases, particularly hepatocellular carcinoma. Through this review, we seek to offer theoretical insights into the potential of MSNs for diagnostic and therapeutic applications in liver disease treatment.

Construction of mesoporous lanthanum oxide and supported Co-N catalysts for high-efficient synthesis of furfuryl alcohol

The mesoporous lanthanum oxide materials were designed via the solvent evaporation-induced self-assembly method, and Co-N/La2O3 catalysts were prepared to evaluate performance in the reaction of furfural hydrogenation. The characterization analyses proved that Co/La2O3 and Co-2N/La2O3 catalysts had high specific surface area and open mesoporous channels (> 20nm), moreover doped nitrogen not only promoted the distribution of Co species and regulated size of metallic Co nanoparticles (~17.37nm), but also increased electron-rich Co0 (57.8%) and CoNx sites. The highest conversion (>99.9%) and selectivity (98.6%) were achieved on Co-2N/La2O3 catalyst under 140oC, 1.5MPa H2 and 3h, which was attributed to the combination of Co0 and CoNx sites enhancing the dissociation of H2 and adsorption of furfural by DFT calculation, meanwhile the doped nitrogen brought more acidic sites (~ 2.81mmol NH3/g) of Co-2N/La2O3 catalyst. Additionally, the Co-2N/La2O3 catalyst showed the stable catalytic activity for 5 recycles and excellent universality for hydrogenation reactions of biomass platform molecules.

Optimizing Etodolac and Quercetin Loaded MSNs Using Taguchi Design: An approach for Enhancing Drug Loading Efficiency.

The application of mesoporous silica nanoparticles (MSN) as a drug carrier system got immense attention in the past few years due to their exceptional high drug loading efficiency. However, the process of drug loading is quite challenging compared to other lipid-based drug delivery systems. Hence, the MSNs using different catalysts were synthesized, and their mesoporous material characteristic was confirmed by the type IV adsorption-desorption isotherm using BET analyzer. The effect of solvent selection and other process parameters (drug to MSNs ratio, period of loading, and stirring speed) on the loading of BCS class II and IV model drugs etodolac(ETD) and quercetin(QUR) respectively were investigated with the help of Taguchi DOE. The predicted value for the highest % drug loading was close to the experimental value(19.04 ± 0.50 % and 11.40 ± 0.18 % for ETD and QUR respectively). It was interesting to note, that the solvent selection had the highest impact on the drug loading of ETD into the MSNs, whereas for QUR this parameter was insignificant. Hence reflecting that a generalized procedure for the drug loading into the MSNs cannot be followed and had to be critically studied. Also, the loading of ETD and QUR into the MSNs improved the aqueous solubility (3.08 and 2.5 folds respectively). Further the in-vitro drug release properties were evaluated for ETD and QUR from MSNs in various drug release mediums to explore their release mechanism from MSNs using in vitro drug release kinetic modelling.

Confined phase behavior of subcritical carbon dioxide in nanoporous media: the effects of pore size and temperature.

This study investigates the effect of confinement on the phase behavior of carbon dioxide (CO2) and its implications for storage in nanometer-scale pores. A patented gravimetric apparatus was employed to experimentally measure the adsorption and desorption isotherms at varying pore sizes and temperatures. The isotherms were generated at temperatures below the critical point of CO2 (from -23.1 to 20 °C) using mesoporous material MCM-41 with pore sizes of 6, 8, 10, and 12 nm. The capillary condensation and bulk saturation pressures were measured from the adsorption isotherms for each pore size and temperature. Meanwhile, the evaporation pressures under confinement were determined from the desorption branches. The experimentally measured bulk saturation and dew point pressures were successfully compared against the NIST data, confirming the accuracy of measurements. All isotherms showed reversible behavior, exhibiting no adsorption-desorption hysteresis, indicating that all temperatures studied here were above the hysteresis critical temperature. For all pore sizes, the amount of CO2 adsorbed in confined spaces decreased with ascending temperatures. Furthermore, the CO2 uptake during capillary condensation showed an inverse correlation with the pore size; smaller pores adsorbed more CO2 due to the higher interaction strength with pore walls than larger counterparts. Furthermore, the results provide an in-depth understanding of the effect of pore size and temperature on the equilibrium behavior of CO2 molecules in confined and bulk spaces of porous media. The results from the present study can significantly aid the storage applications of CO2 in a wide range of natural and synthetic porous materials.

Preparation, characterization, and use of trimethoxy[3-(methylamino)propyl]silane functionalized SBA-15 for Congo Red adsorption

Mesoporous materials have a broad range of applications in industry, and one of which is their potential use in adsorptive separations. This research investigates the use of a secondary amine-functionalized SBA-15 for the separation of a diazo dye, Congo Red (CR), from aqueous solutions. The synthesized SBA-15 was modified with trimethoxy[3-(methylamino)propyl] silane by a post-grafting method. The produced material was characterized using X-ray diffraction, N2 physisorption, scanning electron microscopy, and transmission electron microscopy. The hexagonal mesostructure was preserved after functionalization; however, the specific surface area, pore diameter, and total pore volume of SBA-15 silica decreased. The adsorption of the diazo dye reached equilibrium by 50 minutes, and the data followed pseudo-second-order kinetics. While the yield increased with rising dosage and temperature, it decreased with CR concentration. The maximum adsorption capacity of functionalized SBA-15 (F-SBA-15) for CR uptake was found to be 211.07 mg/g. Thermodynamic data and parameters indicated the potential combination of physical and chemical interactions occurring during the adsorption process. The separation was endothermic and non-spontaneous; the equilibrium data fitted to the Freundlich adsorption isotherm at all tested temperatures. This study demonstrates that the secondary amine-functionalized SBA-15 can be used for the elimination of a toxic anionic diazo dye from aqueous solutions.

Effect of Ethanol Treatment and Calcination Temperature on Water Vapor Adsorption properties of MCM-41.

MCM-41, a mesoporous material with a high surface area and tunable pore size, shows great potential for water vapor adsorption. However, due to its large pore size, the effective adsorption capacity at medium to low relative partial pressures is limited in adsorption chiller applications. In this work, MCM-41 was successfully synthesized at room temperature using cetyltrimethylammonium bromide (CTAB) as a templating agent. Pore size modulation was achieved by treating the MCM-41 gel with ethanol. The results indicated that ethanol likely exerted an inward force on the pore channels, reducing the pore size from 3.418 to 2.583 nm. The water vapor adsorption properties and hydrothermal stability of the ethanol-treated samples were significantly enhanced. Additionally, a dual-atmosphere calcination process at 450 °C was established, showing results comparable to the conventional 550 °C process in terms of template removal. The sample, which combined dual-atmosphere calcination with ethanol treatment, demonstrated a significant increase in the water vapor adsorption capacity, achieving a 1.3-fold improvement compared to the untreated sample. These results provide a feasible reference for the application of MCM-41 in adsorption chillers.

Oxidation of Styrene to Benzaldehyde Using Environmentally Friendly Calcium Sulfate Hemihydrate-Supported Titania Catalysts

This paper presents the synthesis and characterization of calcium sulfate hemihydrate (CSH)-supported titania (TiO2) catalysts and their application in the environmentally friendly oxidation of styrene to benzaldehyde using hydrogen peroxide (H2O2) as the oxidant. The study explores the catalyst's structure-activity relationship, emphasizing the importance of mesoporous materials for enhanced catalytic performance. The CSH-Titania catalysts were synthesized using fish bone-derived CSH as a support, which aligns with green chemistry principles. Characterization techniques such as Fourier Transform Infra Red (FTIR), X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), and Brunauer-Emmett-Teller (BET) surface area analysis confirmed the successful impregnation of titania and its catalytic efficiency. The catalysts exhibited high selectivity for benzaldehyde, achieving up to 49.45% conversion of styrene, with benzaldehyde as being the main product. The research highlights that the catalyst’s performance decreased after calcination due to a reduced surface area and pore volume, yet it maintained recyclability across three cycles with minimal lose in selectivity loss. Overall, this study introduces a cost-effective and sustainable approach to styrene oxidation, demonstrating the potential for industrial application in producing high-value chemicals with minimal environmental impact. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Multipurpose adsorption applications of boron-doped and amino-functionalized magnetic mesoporous silica nanocomposite.

In this study, boron-doped magnetic mesoporous silica nanocomposite was prepared through the hydrothermal synthesis procedure followed by post modification with -NH2 groups. The higher surface area, more ordered mesoporous structure, and higher surface charge density obtained by boron doping and amino functionalization contributed to the use of nanocomposite for multipurpose application functions. When used as an adsorbent for light green (LG) anionic dye, boron-doped nanocomposite exhibited higher adsorption capacity (105.80mg/g) compared to undoped nanocomposite (72.23mg/g), while when used as a drug carrier for Doxorubicin (DOX), a sufficient drug loading capacity (48.0mg/g) was obtained, which is also higher than that of undoped nanocomposite (30.3mg/g). In terms of LG adsorption, the effects such as initial concentration, adsorbent dosage, time, pH, and temperature on the adsorption properties were investigated in detail. Adsorption kinetics, isotherms, thermodynamics, and reusability are discussed. The existence of small quantity of boron doping enhanced the surface charge density from 0.0393 to 0.2854 C/m2, which resulted in higher adsorption capacity for LG adsorption dominated by electrostatic attraction, and led to formation of silanol holes together with the -OH and -NH2 functional groups, which resulted in higher drug loading capacity for DOX adsorption dominated by hydrogen bonding. This promising result provides that boron-doped and -NH2 grafted magnetic mesoporous silica material can function as multipurpose adsorbent for various environmental applications.

Adsorption of selected GHG on metal-organic frameworks in the context of accompanying thermal effects

Thermal effects accompanying gas sorption on micro- and mesoporous materials provide unique insights into the type, course, and efficiency of sorption. In this study, metal-organic frameworks (MOFs) with different topologies and chemical structures were synthesized and investigated: HKUST-1, Ni-MOF-74, UiO-66, and MIL-140A. These MOFs were characterized structurally and sorptively with respect to selected greenhouse gases (GHGs). Sorption capacities for CO2 and CH4 were determined at several temperatures and measurement pressures, and the maximum sorption capacity was determined using the Langmuir-Freundlich model. Thermal effects accompanying adsorption were quantified through the isosteric heat of adsorption parameter. For each MOF, the values of isosteric heat of adsorption were higher for CO2 than for CH4. The values of this parameter was determined in the following order: HKUST-1 > Ni-MOF-74 > UiO-66 > MIL-140A. Energy homogeneity of the adsorbent surface was observed in nearly all cases, except for UiO-66 during CO2 adsorption. Changes in the determined isosteric heat of adsorption of CO2 with increasing sorption capacity were in the range of 5-15 kJ/mol, while for CH4 they ranged from 1.4 to 17 kJ/mol, respectively. The level of thermal selectivity of CO2 over CH4 was determined in the following order: UiO-66 (1.9) > Ni-MOF-64 (1.7) > MIL-140A (1.5) > HKUST-1 (1.1).

Bimetallic Mesoporous MCM-41 Nanoparticles with Ta/(Ti, V, Co, Nb) with Catalytic and Photocatalytic Properties.

Bimetallic (Ta/Ti, V, Co, Nb) mesoporous MCM-41 nanoparticles were obtained by direct synthesis and hydrothermal treatment. The obtained mesoporous materials were characterized by XRD, XRF, N2 adsorption/desorption, SEM, TEM, XPS, Raman, UV-Vis, and PL spectroscopy. A more significant effect was observed on the mesoporous structure, typically for MCM-41, and on optic properties if the second metal (Ti, Co) did not belong to the same Vb group with Ta as V and Nb. The XPS showed for the TaTi-MCM-41 sample that framework titanium is the major component. The new nanoparticles obtained were used as catalysts for oxidation with hydrogen peroxide of olefinic compounds (1,4 cyclohexadiene, cyclohexene, styrene) and photodegradation of organic pollutants (phenol, methyl orange) from water. The results showed improvementsin activity and selectivity in oxidation reactions by the addition of the second metal to the Ta-MCM-41 catalyst. The slow addition of H2O2 was also beneficial for the selectivity of epoxide products and the stability of the catalysts. The band gap energy values decreased in the presence of the second metal, and the band edge diagram evidenced positive potential for all the conduction bands of the bimetallic samples. The highestlevels of photocatalytic degradation were obtained for the samples with TaTi and TaV.

Lignin Polyurethane Aerogels: Influence of Solvent on Textural Properties.

This study explores the innovative potential of native lignin as a sustainable biopolyol for synthesizing polyurethane aerogels with variable microstructures, significant specific surface areas, and high mechanical stability. Three types of lignin-Organosolv, Aquasolv, and Soda lignin-were evaluated based on structural characteristics, Klason lignin content, and particle size, with Organosolv lignin being identified as the optimal candidate. The microstructure of lignin polyurethane samples was adjustable by solvent choice: Gelation in DMSO and pyridine, with high affinity to lignin, resulted in dense materials with low specific surface areas, while the use of the low-affinity solvent e.g acetone led to aggregated, macroporous materials due to microphase separation. Microstructural control was achieved by use of DMSO/acetone and pyridine/acetone solvent mixtures, which balanced gelation and phase separation to produce fine, homogeneous, mesoporous materials. Specifically, a 75% DMSO/acetone mixture yielded mechanically stable lignin polyurethane aerogels with a low envelope density of 0.49 g cm-3 and a specific surface area of ~300 m2 g-1. This study demonstrates a versatile approach to tailoring lignin polyurethane aerogels with adjustable textural and mechanical properties by simple adjustment of the solvent composition, highlighting the critical role of solvent-lignin interactions during gelation and offering a pathway to sustainable, high-performance materials.

Hf Doping Boosts the Excellent Activity and Durability of Fe-N-C Catalysts for Oxygen Reduction Reaction and Li-O2 Batteries.

Developing highly active and durable non-noble metal catalysts is crucial for energy conversion and storage, especially for proton exchange membrane fuel cells (PEMFCs) and lithium-oxygen (Li-O2) batteries. Non-noble metal catalysts are considered the greatest potential candidates to replace noble metal catalysts in PEMFCs and Li-O2 batteries. Herein, we propose a novel type of non-noble metal catalyst (Fe-Hf/N/C) doped with Hf into a mesoporous carbon material derived from Hf-ZIF-8 and co-doping with Fe and N, which greatly enhanced the activity and durability of the catalyst. When applied in the cathode of PEMFCs, the current density can reach up 1.1 and 1.7 A cm-2 at 0.7 and 0.6 V, respectively, with a maximum power density of 1.15 W cm-2. The discharge capacity of the Li-O2 batteries is up to 15,081 mAh g-1 with Fe-Hf/N/C in the cathode, which also shows a lower charge overpotential, 200 mV lower than that of the Fe/N/C. Additionally, the Fe-Hf/N/C catalyst has demonstrated better stability in both PEMFCs and Li-O2 batteries. This reveals that Hf can not only optimize the electronic structure of iron sites and increase the active sites for the oxygen reduction reaction, but can also anchor the active sites, enhancing the durability of the catalyst. This study provides a new strategy for the development of high-performance and durable catalysts for PEMFCs and Li-O2 batteries.