Tunable Pore Size Research Articles

Pore-size tuning of hard carbon to optimize its wettability for efficient Na+ storage

The Na+ reaction kinetics of hard carbon can be enhanced by improving its wettability through pore-size tuning. The optimized carbonaceous anodes with an average pore size of 6.1 nm exhibited the most enhanced Na+ storage capability.

Subangstrom tuning of pore size for selective separation of radioactive strontium over environmental calcium by lanthanide–oxalate frameworks

Subangstrom tuning of pore size for selective separation of radioactive strontium over environmental calcium by lanthanide–oxalate frameworks

Fine tuning of pore size in metal–organic frameworks for superior removal of U(vi) from aqueous solution

The pore structure of metal–organic frameworks (MOFs) is crucial to their adsorption performance, and it is still a challenge to precisely control the pore size to realize superior removal of uranium.

UiO-67 MOF-Based Catalyst as A Potential Photocatalyst for Co2 Conversion to Methanol Complimented by RSM Studies

Metal-organic frameworks (MOFs) have received significant attention in recent years due to their fascinating properties, such as high surface area, porosity, tuneable pore size, and structural flexibility. These characteristics make them promising candidates for various applications, particularly in the photocatalytic conversion of carbon dioxide (CO2). This research investigated the unitisation of Polyoxometalates (POMs) incorporated within MOFs as catalysts for converting CO2 to methanol. The POM@MOF catalyst was prepared by the solvothermal method, and its physicochemical properties were characterised through various techniques, including FTIR, UV-VIS, PXRD, TGA, FESEM, and BET. Response Surface Methodology (RSM) based on Central Composite Design (CCD) was employed to optimise the reaction conditions, focusing on catalyst loading and reaction time. Methanol concentration in the product was determined using HPLC. Notably, the encapsulation of Keggin SW12 into UiO-67(Zr) resulted in better physicochemical properties than pristine UiO-67. The optimal reaction conditions were determined to be a catalyst loading of 1.0 g/L and a reaction time of 3 hours. While the photocatalytic CO2 conversion was successfully conducted, methanol was not detected in both the proposed and modified experimental setups due to the low methanol concentration and the limitations of the detection instruments. This research establishes a lower-limit benchmark and contributes to the development of sustainable processes for CO2 photocatalytic conversion to methanol utilising the SW12@UiO-67 catalyst.Keywords: CO2 conversion, Photocatalyst, RSM, UiO-67, POM@MOF

Solvent-free mechanochemical synthesis of a sodium disulfonate covalent organic framework for simultaneous highly efficient selective capture and sensitive fluorescence detection of fluoroquinolones

Covalent organic frameworks (COFs) have great adsorption potential due to their tunable pore size and pore architecture as well as tailorable functionalities. However, the green and rapid synthesis of COFs with excellent adsorption properties remains a great challenge. Here, we presented a solvent-free and facile mechanochemical approach for the synthesis of COFs. The as-prepared COF TpBD-(SO3Na)2 containing sulfonate ions exhibited good thermal and chemical stability and can serve as an effective adsorbent for selective capture of fluoroquinolone antibiotics (FQs) benefiting from the ionic interface and abundant negatively charged sites. The maximum adsorption capacities of norfloxacin, enoxacin, and ciprofloxacin were 1709.6, 1661.5, and 1362.8 mg g−1, respectively, which outperformed those of other reported adsorbents. The adsorption mechanism was deeply explored through characterizations combined with density functional theory calculations, proving the synergistic adsorption effects of TpBD-(SO3Na)2 and FQs, including π-π* interactions, electrostatic interactions, and hydrogen bonding. Moreover, a fluorescence detection platform for FQs was developed based on the fluorescence signal of sodium disulfonate TpBD-(SO3Na)2. The limit of detection of norfloxacin was 8 nmol/L with a linear range from 0.03 to 6 μmol/L. This research provides a new strategy for the green synthesis of COFs and expands their application in the synchronous detection and removal of FQs in aquatic environments.

Precise Preparation of Triarylboron-Based Graphdiyne Analogues for Gas Separation.

A series of triarylboron-based graphdiyne analogues (TAB-GDYs) with tunable pore size were prepared through copper mediated coupling reaction. The elemental composition, chemical bond, morphology of TAB-GDYs were well characterized. The crystallinity was confirmed by selected area electron diffraction (SAED) and stacking modes were studied in combination with high resolution transmission electron microscope (HRTEM) and structure simulation. The absorption and desorption isotherm revealed relatively high specific surface area of these TAB-GDYs up to 788 m2 g-1 for TMTAB-GDY, which decreased as pore size enlarged. TAB-GDYs exhibit certain selectivity for CO2 /N2 (21.9), CO2 /CH4 (5.3), CO2 /H2 (41.8) and C2 H2 /CO2 (2.3). This work has developed a series of boron containing two-dimensional frameworks with clear structures and good stability, and their tunable pore sizes have laid the foundation for future applications in the gas separation field.

Precise Preparation of Triarylboron‐Based Graphdiyne Analogues for Gas Separation

AbstractA series of triarylboron‐based graphdiyne analogues (TAB‐GDYs) with tunable pore size were prepared through copper mediated coupling reaction. The elemental composition, chemical bond, morphology of TAB‐GDYs were well characterized. The crystallinity was confirmed by selected area electron diffraction (SAED) and stacking modes were studied in combination with high resolution transmission electron microscope (HRTEM) and structure simulation. The absorption and desorption isotherm revealed relatively high specific surface area of these TAB‐GDYs up to 788 m2 g−1 for TMTAB‐GDY, which decreased as pore size enlarged. TAB‐GDYs exhibit certain selectivity for CO2/N2 (21.9), CO2/CH4 (5.3), CO2/H2 (41.8) and C2H2/CO2 (2.3). This work has developed a series of boron containing two‐dimensional frameworks with clear structures and good stability, and their tunable pore sizes have laid the foundation for future applications in the gas separation field.

Based on high cross-linked structure design to fabricate PEI-based nanofiltration membranes for Mg2+/Li+ separation

With the rapid development of Li-ion batteries (LiBs), the demand for lithium sharply increased. Salt lakes contribute to major extractable lithium in the world, however, the efficient separation of Mg2+ and Li + remains a challenge. The PEI-based nanofiltration (NF) membrane shows great potential for Mg2+/Li+ separation in recent studies, due to its positively charged surface and tunable pore size. In this work, ethylenediamine-terminated polyethyleneimine (EDA@PEI) was utilized as the aqueous monomer reacting with trimesoyl chloride (TMC) via interfacial polymerization (IP) to fabricate a new class of PEI-based NF membranes. This work explored critical membrane fabrication parameters and characterizations of EDA@PEI NF membranes. Additionally, this work compared EDA@PEI-TMC and PEI-TMC membranes on their physicochemical properties and NF performance. The results show that PEI containing EDA groups at ends provides the probability for connection of the backbone via TMC, thus enhancing the cross-linking degree (DNC) of EDA@PEI NF membranes. Meanwhile, the presence of EDA groups enhances the Zeta potential of membranes. The best-performing EDA@PEI-TMC membrane exhibits the highest rejection for Mg2+ of 99.21 %, and excellent Mg2+/Li + separation that SLi/Mg reaches 69.20, 80.62 and 46.79 at Mg2+/Li+ mass ratios of 40:1, 60:1, and 120:1, respectively. During a 48-h NF test, EDA@PEI-TFC membrane shows consistent performance and steady flux. This work demonstrates the great application potential of EDA@PEI NF membranes for Mg2+/Li+ separation, and provides a candidate for fabricating PEI-based NF membranes.

(Digital Presentation) New Magnetron Sputtering Fabrication Process for Ba0.5Sr0.5Co0.8Fe0.2O3- δ Miec Thin Film Membranes on Porous Support for Oxygen Permeation Applications

Mixed ionic electronic conductor (MIEC) membranes provide a great route for introducing oxygen to combustion and reforming processes of new fuels such as green ammonia. Ba0.5Sr0.5Co0.8Fe0.2O3- δ (BSCF) is known to be one of the most widely utilized perovskite material applied as oxygen transport membrane, as it possesses elevated oxygen permeability up to 7 ml(STP)·min-1·cm-2 at a temperature range of 850-900°C. Application of thin MIEC films of thicknesses of around 500 nm – 5 µm allow for reduction of Ohmic resistance for transport processes and sufficient oxygen permeation at lower temperatures as compared to bulk membranes, which is of great advantage with regard to materials stability and quality of sealing. However, fabrication techniques of thin MIEC membranes staunchly influence their phase purity. Crystallinity, microstructure and correlated oxygen diffusion properties as well as stability of membrane-substrate interfaces. Physical vapour deposition (PVD) such as magnetron sputtering (MS) is successfully applied to produce a dense and pinhole-free membrane with thicknesses ranging from 100 nm nanometer to a few micrometers. Challenges due to large size porosity of the ceramic substrate were addressed by tuning of the substrate porosity, ensuring formation of a continues layer and stability of the thin membranes. In this work, we report on the influence of the MS process parameters, as well as subsequent annealing techniques of both thermal annealing (TA) and line beam Laser annealing (LA) on the microstructure of a fabricated asymmetric membrane (AsM) consisting of BSCF thin membrane on a BSCF support wit tunable pore sizes. Oxygen permeability of the AsM was investigated at high temperatures (850-900 °C). For a substrate pore size of around 3 µm, BSCF membrane thicknesses of 1 to 5 µm could be applied for fabrication of AsM, resulting in a 2-fold increase of oxygen permeability ~5 ml.min-1.cm-2 at a temperature of 900 °C as compared to a bulk BSCF support of ~2 mm thickness, whereas comparable oxygen permeation is already reached at a temperature of 700°C by the thin membrane. Contrariwise, the one with high porosity (~10 µm) required the deposition of thicker layers, which obstruct the oxygen diffusion and inhibited the permeation. The results have optimised sputtering process parameters, supports porosity and TA&/SLA parameters, are key factors for producing thin film membrane exhibiting high oxygen flux and good stability.

Hyper-crosslinked Isoporous Block Copolymer Membranes with Robust Solvent Resistance and Customized Pore Sizes for Precise Separation.

Isoporous block copolymer membranes are viewed as the next-generation separation membranes for their unique structures and urgent application in precise separation. However, an obvious weakness for such membranes is their poor solvent-resistance which limits their applications to aqueous solution, and isoporous membranes with superior solvent-resistance and tunable pore size have been rarely prepared before. Herein, self-supporting isoporous membranes with excellent solvent resistance are prepared by the facile yet robust hyper-crosslinking approach which is able to create a rigid network in whole membranes. The hyper-crosslinking is found to be a novel and non-destructive approach that does not change pore size and isoporous structure during the reaction, and the resulting hyper-crosslinked isoporous membranes display superior structural and separation stability to a broad range of solvents with varied polarities for months to years. More importantly, hyper-crosslinking has proved to be a universal strategy that is applicable to isoporous membranes with varied pore size and pore chemistry, offering an important opportunity to prepare solvent-resistant isoporous membranes with customizable pore size and pore functionality that are important to realize their accurate separations in organic solvents. This concept is demonstrated finally by precise and on-demand separation of nanoparticles with the prepared membranes.

Advances in Mn‐Based MOFs and Their Derivatives for High‐Performance Supercapacitor

AbstractAs the most widely used metal material in supercapacitors, manganese (Mn)‐based materials possess the merits of high theoretical capacitance, stable structure as well as environmental friendliness. However, due to poor conductivity and easy accumulation, the practical capacitance of Mn‐based materials is far lower than that of theoretical value. Therefore, accurate structural adjustment and controllable strategies are urgently needed to optimize the electrochemical properties of Mn‐based materials. Metal‐organic frameworks (MOFs) are porous materials with high specific surface area (SSA), tunable pore size, and controllable structure. These features make them attractive as precursors or scaffold for the synthesis of metal‐based materials and composites, which are important for electrochemical energy storage applications. Therefore, a timely and comprehensive review on the classification, design, preparation and application of Mn‐based MOFs and their derivatives for supercapacitors has been given in this paper. The recent advancement of Mn‐based MOFs and their derivatives applied in supercapacitor electrodes are particularly highlighted. Finally, the challenges faced by Mn‐MOFs and their derivatives for supercapacitors are summarized, and strategies to further improve their performance are proposed. The aspiration is that this review will serve as a beneficial compass, guiding the logical creation of Mn‐based MOFs and their derivatives in the future.

Recent Advancement in Natural Gas Storage using Metal-Organic Frameworks

The global quest for cleaner energy sources has highlighted the potential of natural gas. Despite its environmental advantages and abundance, challenges such as energy density, cost, and storage methods hinder its broader use. This paper explores these issues, specifically investigating Metal-Organic Frameworks (MOFs) for methane adsorption and storage. MOFs possess high surface area, tunable pore sizes, strong methane affinity, and stability. This paper reviews recent advancement in this field, particularly, the research surrounding adsorbent HKUST-1, a MOF known for its high gravimetric uptake but falling short in volumetric methane adsorption capacity. Through a sol-gel process, a denser, mechanically stable version of HKUST-1 was synthesized, meeting the Department of Energy's standards. Simultaneously, the study developed a production protocol for UiO-66, improving the volumetric methane working capacity by 11%. Additionally, another study demonstrated that composites of HKUST-1 and γ-Al2O3 exhibited superior methane adsorption, thermal stability, and potential for large-scale synthesis. These advancements in MOFs present the possibility of efficient methane storage, pushing towards wider natural gas adoption, reducing reliance on traditional fossil fuels, and promoting a cleaner, sustainable energy future.

Recent Advances in and Applications of Electrochemical Sensors Based on Covalent Organic Frameworks for Food Safety Analysis.

The international community has been paying close attention to the issue of food safety as a matter of public health. The presence of a wide range of contaminants in food poses a significant threat to human health, making it vital to develop detection methods for monitoring these chemical contaminants. Electrochemical sensors using emerging materials have been widely employed to detect food-derived contaminants. Covalent organic frameworks (COFs) have the potential for extensive applications due to their unique structure, high surface area, and tunable pore sizes. The review summarizes and explores recent advances in electrochemical sensors modified with COFs for detecting pesticides, antibiotics, heavy metal ions, and other food contaminants. Furthermore, future challenges and possible solutions will be discussed regarding food safety analysis using COFs.

Precise Tuning of Hollow and Pore Size of Bimetallic MOFs Derivate to Construct High-Performance Nanoscale Materials for Supercapacitors and Sodium-Ion Batteries.

Precise control of pore volume and size of carbon nanoscale materials is crucial for achieving high capacity and rate performances of charge/discharge. In this paper, starting from the unique mechanism of the role of In, Zn combination, and carboxyl functional groups in the formation of the lumen and pore size, the composition of InZn-MIL-68 is regulated to precisely tune the diameter and wall pore size of the hollow carbon tubes. The hollow carbon nanotubes (CNT) with high-capacity storage and fast exchange of Na+ ions and charges are prepared. The CNT possess ultra-high specific capacitance and ultra-long cycle life and also offer several times higher Na+ ion storage capacity and rate performance than the existing CNTs. Density functional theory calculations and tests reveal that these superior characteristics are attributed to the spacious hollow structure, which provides sufficient space for Na+ storage and the tube wall's distinctive porosity of tube wall as well as open ends for facilitating Na+ rapid desorption. It is believed that precise control of sub-nanopore volume and pore size by tuning the composition of the carbon materials derived from bimetallic metal-organic frameworks (MOFs)will establish the basis for the future development of high-energy density and high-power density supercapacitors and batteries.

Metal-organic frameworks: Drug delivery applications and future prospects.

Metal-organic frameworks (MOFs) have gained incredible consideration in the biomedical field due to their flexible structural configuration, tunable pore size and tailorable surface modification. These inherent characteristics of MOFs portray numerous merits as potential drug carriers, depicting improved drug loading, site-specific drug delivery, biocompatibility, biodegradability, etc. The current review article sheds light on the synthesis and use of MOFs in drug delivery applications. In the beginning, a brief overview of the key components and efficient fabrication techniques for MOF synthesis, along with its characterization methods, have been presented. The MOFs-based formulations have been critically discussed. The application of the design of experiments (DoE) approach to optimize MOFs has been elucidated. The MOFs-based formulations, especially the application of stimuli-responsive MOFs for site-specific drug delivery, have been deciphered. Along with drug release kinetic models, several administration methods for MOFs have also been enunciated. Subsequently, MOFs as future potential drug carriers have been elaborated. Recently, MOFs have emerged as versatile drug delivery carriers possessing customization potential and meeting the needs of spatio-temporal drug delivery. Researchers have devised several environment-friendly approaches for MOF construction and surface modification. Owing to stimuli-responsive potential, MOFs have demonstrated their prominent therapeutic efficacy via several routes of administration. The numerous benefits of MOFs would certainly open up a new vista for its novel drug delivery applications.

Synthesis of porous silica from wasted SiO2‐containing molding compounds

AbstractMaterialsIn this study, we provided a simple method to extract the silicate species from the waste silica‐containing molding compounds from the semiconducting industry.MethodsRecycled sodium silicate solution was obtained from alkaline extraction of the silica fillers in the waste molding compounds and dried and redissolved in appropriate amount of water.ResultsPorous silica of high surface area (>500 m2g−1) and tunable pore size (1.5–5.0 nm) could be feasibly synthesized by using the recycled sodium silicate as silica source and nature‐friendly homopolymer polyethylene glycol (PEG) as an organic template. The pore size of the PEG‐templating silicas was made tunable by hydrothermal treatment at different pH.ConclusionTo reduce the emission of CO2 gas from the removal of the PEG template, porous silica with a large surface area has been prepared at a low PEG/sodium silicate weight ratio of 1/20.

Linking processing to formulation in dynamic membranes of tunable pore size for lemon oil emulsions

Lemon oil is widely used for food flavoring purposes, but due to its low water solubility and tendency to oxidation, requires encapsulation in oil-in-water (O/W) emulsions. Therefore, this study assesses the use of two natural biopolymers and a tailor-made one to encapsulate lemon oil with a dynamic membrane of tunable pore size (DMTS). This emulsification system, consisting of an outer bed layer of silica beads sitting upon a metal microporous metallic membrane, overcomes the limitations of conventional emulsification membranes, such as low throughput, complex cleaning before reuse, fixed membrane thickness and pore size, and significative protein fouling. The effects of the DMTS characteristics on the droplet size distribution and emulsion productivity were studied. The results demonstrate that mono-dispersed emulsions can be obtained using dynamic membranes for all the biopolymers studied and the productivity can reach 1000 m3 m−2h−1 pointing out the suitability of this system for scale-up.

Chiral metal–organic framework [Zn2(D-Cam)2(4,4′-bpy)]n@SiO2 core–shell composite for HPLC separation

Chiral metal–organic frameworks, an emerging type of chiral porous materials, possess many outstanding characteristics such as high surface area, tunable pore sizes, and good chemical stability. Herein, we prepared a chiral [Zn2(D-Cam)2(4,4′-bpy)]n@SiO2 core–shell composite on the SiO2-NH2 microspheres by an in-situ growth method. The prepared [Zn2(D-Cam)2(4,4′-bpy)]n@SiO2-packed column exhibited high-resolution separation of racemic compounds and positional isomers at a low column backpressure (9–12 bar). Twelve pairs of enantiomers including alcohols, amines, epoxides, ketones, and esters were well resolved with sharp peak shapes on the [Zn2(D-Cam)2(4,4́-bpy)]n@SiO2 chromatographic column. Compared the separation performance of [Zn2(D-Cam)2(4,4́-bpy)]n@SiO2-packed column and two chromatographic columns (commercial Chiralpak AD-H column and as-prepared SiO2-NH2 column), the [Zn2(D-Cam)2(4,4′-bpy)]n-packed column and the commercial Chiralpak AD-H column have a good complementarity in chiral separation, and it also offered better separation performance compared to the SiO2-NH2 column for separating positional isomers. The effects of column temperature and analyte mass on the HPLC separation were investigated. Additionally, the [Zn2(D-Cam)2(4,4́-bpy)]n@SiO2 packed column has good repeatability and stability for HPLC separation of enantiomers and positional isomers. The relatvive standard deviations (RSDs) for repeated separations of 2,2,2-trifluoro-1-(9-anthryl)ethanol and o, m, p-bromoaniline were less than 0.8 % and 1.2 % for the retention time and peak area, respectively. After continuous use for one month, the RSDs for the retention time and peak area of them were in the range of 1.1–1.3 % and 1.5–1.8 % (inter-day and intra-day, n = 5), respectively. This work also indicates that the chiral MOFs@SiO2 composites are promising for HPLC separation.

Aligned Collagen Sponges with Tunable Pore Size for Skeletal Muscle Tissue Regeneration.

Volumetric muscle loss (VML) is a traumatic injury where at least 20% of the mass of a skeletal muscle has been destroyed and functionality is lost. The standard treatment for VML, autologous tissue transfer, is limited as approximately 1 in 10 grafts fail because of necrosis or infection. Tissue engineering strategies seek to develop scaffolds that can regenerate injured muscles and restore functionality. Many of these scaffolds, however, are limited in their ability to restore muscle functionality because of an inability to promote the alignment of regenerating myofibers. For aligned myofibers to form on a scaffold, myoblasts infiltrate the scaffold and receive topographical cues to direct targeted myofiber growth. We seek to determine the optimal pore size for myoblast infiltration and differentiation. We developed a method of tuning the pore size within collagen scaffolds while inducing longitudinal alignment of these pores. Significantly different pore sizes were generated by adjusting the freezing rate of the scaffolds. Scaffolds frozen at -20 °C contained the largest pores. These scaffolds promoted the greatest level of cell infiltration and orientation in the direction of pore alignment. Further research will be conducted to induce higher levels of myofiber formation, to ultimately create an off-the-shelf treatment for VML injuries.

Recent progress and future outlook on hybrid aerogel materials for sustainable CO2 capture: A mini review

Presently, considerable research is going on to find novel materials for capturing carbon dioxide (CO2). Aerogels are an emerging class of composites with distinct properties such as tunable pore size, adjustable framework, high surface area and abundant active sites which helps in efficient CO2 adsorption. In this mini review, different types of aerogels and their combinations with different materials along with different methods for the synthesis of hybrid aerogels are also discussed for CO2 adsorption. Considerable attention has been given on the characterization and performance of several hybrid aerogels for CO2 capture that are systematically tabulated. The review also highlights the future scope of hybrid aerogel. The excellent adsorption properties for CO2 capture and selectivity towards CO2, hybrid aerogel could be a promising material for CO2 adsorption and a promising avenue towards achieving sustainable solutions for mitigating climate change.