Porous materials for hydrogen storage

Three-Dimensional Covalent Organic Framework for Efficient Hydrogen Storage through Polarization-Wall Engineering

Covalent organic frameworks (COFs), characterized by high surface areas and tunable pore structures/environments, are regarded as a promising alternative to physisorption H2 storage materials. However, their interaction with hydrogen is often too weak, necessitating the exploration of strategies to enhance sorption heat. Herein, we strengthened the adsorption induction of COF on H2 through a polarized wall engineering. The fluorine groups on the pore wall of three-dimensional COFs polarize their surrounding regions, resulting in high sorption heat sites. Due to the enhanced H2 sorption heat, the total H2 uptake of 3D-F-COF is up to to 5.96 wt % at 77 K and 90 bar. Moreover, the H2 adsorption enhancement effect of the polar group does not involve chemisorption, and the material exhibits excellent cycling stability. These results reveal that modulating the H2 sorption heat by incorporating polar groups is a promising strategy for achieving efficient H2 storage in porous materials.

Porphyrin based covalent organic frameworks via self-polycondensation for heterogeneous photocatalysis

A novel porphyrin based covalent organic frameworks (Por-BABN-COF) has been successfully constructed via self-polycondensation of a newly developed A2B2 porphyrin building block possessing two amino groups and two neopentyl acetal at the meso-position. Por-BABN-COF was employed as a heterogeneous photocatalyst for the selective oxidation of sulfides and CO2 cycloaddition due to its superior light absorption capacity, strong crystallinity and high stability. The high conversion, good selectivity and excellent reusability indicate Por-BABN-COF is a promising photocatalyst for both reactions. Mechanistic investigations confirm that electron transfer pathways contribute to the formation of sulfoxides. This study presents a new strategy for designing and developing high-efficient porphyrin-based COFs as heterogeneous photocatalysts for selective organic transformations.

A Needle in a Haystack: Transient Porosity in a Closed Pore Square Lattice Coordination Network

Guest transport through discrete voids (closed pores) in crystalline solids is poorly understood. Herein, we report the gas sorption properties of a nonporous coordination network, {[Co(bib)2Cl2] ⋅ 2MeOH}n (sql-bib-Co-Cl-α), featuring square lattice (sql) topology and the bent linker 1,3-bis(1H-imidazol-1-yl)benzene (bib). The as-synthesized sql-bib-Co-Cl-α has 11.3 % (313 Å3) of its unit cell volume in closed pores occupied by methanol (MeOH). Upon desolvation and air exposure, sql-bib-Co-Cl-α underwent a single-crystal to single-crystal (SC-SC) phase transformation to sql-bib-Co-Cl-β', wherein MeOH was replaced by water. Activation (vacuum or N2 flow) resulted in dehydration and retention of the closed pores, affording sql-bib-Co-Cl-β with 7.7 % (194 Å3) guest-accessible space. sql-bib-Co-Cl-β was found to preferentially adsorb C2H2 (at 265 K) over CO2 (at 195 K) through gate-opening mechanisms, at gate-opening pressures of 59.8 and 27.7 kPa, respectively, while other C2 gases were excluded. PXRD was used to monitor transformations between the three phases of sql-bib-Co-Cl, while in situ DSC, in situ SCXRD under CO2 pressure, and computational studies provided insight into the guest transport mechanism, which we attribute to the angular, flexible nature of the bib ligand. Further, the preferential adsorption of C2H2 over CO2 and other C2 gases suggests that transiently porous sorbents might have utility in separations.

Hierarchical interface engineering for advanced magnesium-based hydrogen storage: synergistic effects of structural design and compositional modification

Interface engineering fundamentally revolutionizes magnesium-based hydrogen storage systems by orchestrating atomic-scale interactions and mass transport pathways through precisely engineered structural architectures and chemical environments. This review presents a paradigm-shifting framework that transcends conventional surface modification approaches, establishing interface engineering as a cornerstone strategy for next-generation hydrogen storage materials. Through sophisticated control of interface architecture - from one-dimensional confined channels that facilitate directional hydrogen diffusion, to two-dimensional platforms that maximize catalytic interactions, to three-dimensional networks that optimize spatial organization - we unlock unprecedented control over hydrogen storage dynamics. The strategic modulation of interface chemistry creates synergistic effects between structural features and catalytic functionalities. Metal-metal interfaces orchestrate electron transfer processes and facilitate hydrogen dissociation, while engineered support interfaces maintain structural integrity and enhance cycle life. This multi-level interface control enables simultaneous optimization of thermodynamic destabilization and kinetic enhancement. Advanced characterization and theoretical modeling reveal that the controlled evolution of interface structure during hydrogen cycling plays a pivotal role in determining long-term performance stability. Our comprehensive analysis establishes fundamental correlations between interface architecture and hydrogen storage mechanisms, providing critical insights for rational material design. The review concludes by identifying key challenges and opportunities in translating these interface engineering principles into practical energy storage technologies, offering a roadmap for future development of high-performance magnesium-based hydrogen storage systems.

Enhanced Conductivity in Conjugated Microporous Polymers via Integrating of Carbon Nanotubes for Ultrasensitive NO2 Chemiresistive Sensor

Conjugated microporous polymers (CMPs) present high promise for chemiresistive gas sensing owing to their inherent porosities, high surface areas, and tunable semiconducting properties. However, the poor conductivity hinders their widespread application in chemiresistive sensing. In this work, three typical CMPs (PSATA, PSATB, and PSATT) are synthesized and their chemiresistive gas sensing performance is investigated for the first time. To further improve performance, PSATT are modified on the surface of amino-functionalized multi-walled carbon nanotubes (NH2-MWCNTs) to improve the conductivity. As a result, the obtained material, PSATT-7NC exhibited a high sensitivity of 9766% toward 4 ppm NO2, which is 2.5 times higher than that of pristine PSATT. It also demonstrated remarkable selectivity and excellent long-term stability. Furthermore, the lowest limit of detection (0.79 ppb) among all polymers-based sensors is achieved at a low operating temperature of 100 °C. This work provides a valuable strategy into the development of a new material platform for advancing high-performance gas sensing applications.

[Cu2(trz-ia)2]─An Ultramicroporous Cu2 Paddle Wheel Triazolyl Isophthalate MOF: A Comparative Study of Its Properties in Dihydrogen Adsorption and Isotopologue Separation

A Cu2 paddle wheel-based metal-organic framework, [Cu2(trz-ia)2] (trz-ia2- = 5-(4H-1,2,4-triazol-4-yl) isophthalate), is investigated for hydrogen adsorption and hydrogen isotopologue separation. Its ultramicroporous structure with pore diameters ranging from 0.35 to 0.53 nm allows for strong interactions with dihydrogen molecules, resulting in steep H2 uptake and heat of adsorption Qads = 9.7 kJ mol-1. Notably, the hydrogen density inside the pores is 43.9 g L-1 at 77 K and 100 kPa. Thermal desorption spectroscopy (TDS) after exposure to a H2/D2 mixture indicates dihydrogen isotopologue separation with a selectivity of S = 6 at 30 K and a high uptake of D2. These findings are compared with numerous other metal-organic frameworks (MOFs) and related to their pore size.

Modulating Coordination Environment of Single Nickel Atom in Covalent Organic Framework to Enhance Photocatalytic Hydrogen Evolution Reaction

Covalent organic frameworks (COFs) have emerged as fascinating platforms for photocatalytic hydrogen evolution reactions in recent years. However, the relationship between the coordination environment of metals in a covalent organic framework and catalytic properties is still rarely studied. In this study, a covalent organic framework (COF-BP), containing a benzothiazole unit with typical electron-withdrawing properties, was successfully synthesized from 4,4'-(benzo-2,1,3-thiadiazole-4,7-diyl)dianiline and 3,3',5,5'-tetraformyl-4,4'-biphenyldiol. The free hydroxyl and imine groups in COF-BP were used for postmodification loading of Ni2+ to form COF-BP-Ni1, and then the coordination environment of Ni was further modulated through ligand exchange, replacing acetate anions by salicylideneaniline to construct COF-BP-Ni2 containing Schiff base-Ni complexes. The experimental results demonstrated that modulating the ligands of metal within the COF to alter its coordination environment enhanced the synergy with the COF framework, thereby promoting photoelectron separation and transfer, further significantly improving its photocatalytic activity. COF-BP-Ni2 showed good photocatalytic hydrogen evolution performance with a rate of 12.21 mmol g-1 h-1 in the presence of Pt as cocatalyst, which was 2.2-fold that of COF-BP-Ni1 at the same condition. Interestingly, the hydrogen evolution rate of COF-BP-Ni2 reaches 1.27 mmol g-1 h-1 even without Pt as a cocatalyst. This work provides new insights into how to improve the catalytic performance of COF-based catalysts.

Implementation of Genetic Algorithms to Optimize Metal-Organic Frameworks for CO2 Capture

Metal-organic frameworks (MOFs) are promising materials for CO2 capture with the potential to use less energy than current industrial CO2 capture methods. MOFs are highly versatile sorbents, and there is an almost unlimited number of MOFs that could be synthesized. In this work, we used a genetic algorithm (GA) and grand canonical Monte Carlo (GCMC) simulations to efficiently search for high-performing MOFs for CO2 capture. We analyzed the effects of important GA parameters, including the mutation probability, the number of MOFs per generation, and the number of GA generations, on the GA performance. We performed GCMC simulations on-the-fly during the GA procedure to determine the performance of proposed MOFs and optimized their structures using multiple objective functions across different topologies. The GA was able to determine top-performing MOFs balancing CO2 selectivity versus working capacity and reduced the cost of molecular simulations by a factor of 25 versus brute-force screening of an entire database of structures.

Recent advances in nanoporous organic polymers (NPOPs) for hydrogen storage applications

Nanoporous organic polymers (NPOPs) have emerged as versatile materials with robust thermal stability, large surface area (up to 2500 m2 g-1), and customizable porosity, making them ideal candidates for advanced hydrogen (H2) storage applications. This review provides a comprehensive analysis of various NPOPs, including covalent organic frameworks (COFs), hypercrosslinked polymers (HCLPs), conjugated microporous polymers (CMPs), and porous aromatic frameworks (POAFs). Notably, these materials demonstrate superior H2 storage capacities, achieving up to 10 wt% at cryogenic temperatures, which is essential for applying H2 as a clean energy carrier. The review also highlights recent advancements, such as integrating metal-organic frameworks (MOFs) into NPOPs, further enhancing storage capacities by up to 30%. Their multifaceted properties underpin various applications, from fuel storage and gas separation to water treatment and optical devices. This review explores the significance and versatility of NPOPs in H2 storage due to their unique properties and enhanced storage capacities. Additionally, recent advancements in utilizing NPOPs for H2 storage are highlighted with a detailed discussion of emerging trends and the synthesis of innovative NPOPs. The review concludes with a discussion of the advantages, applications, challenges, research, and future directions for research in this area.

Cerium Oxide-Induced Synchronous Lattice Oxygen Activation and Accelerated Deprotonation Kinetics in Cobalt (oxy)Hydroxide for Robust Water Oxidation

Theoretically, triggering the lattice oxygen mechanism (LOM) of the catalysts during the alkaline oxygen evolution reaction (OER) can effectively break through the thermodynamic limitations, while following this path, the rate of simultaneous deprotonation also determines the overall kinetics. A cerium oxide units-modified cobalt (oxy)hydroxide nanocomposite of CeO2-CoOOH/NF is proposed, where the Ce(4f)-O(2p)-Co (3d) coupling with sites interaction mediates the Co─O Mott-Hubbard splitting state to trigger efficient LOM. Meanwhile, the 4f orbital electron-rich state near the Fermi level is favorable for proceeding the electron-involved deprotonation behavior. All these empower CeO2-CoOOH/NF with considerable OER activity, which delivers an overpotential of 249 mV at 10 mA cm-2, and coupling with commercial Pt/C in anion exchange membrane water electrolyze (AEMWE) to realize energy-saving hydrogen production. This work is instructive for the design of high-performance OER catalysts through controlling the electron orbitals hybridization state of the catalysts to synchronously accelerate the kinetics of each link in OER.

High-Entropy Zeolitic Imidazolate Frameworks for Dynamic Hydrogen Isotope Separation

Entropy-driven strategy enables the systematic design of complex systems by using entropy as a quantifiable design parameter for the degree of mixing. In this study, we present mixed-linker zeolitic imidazolate frameworks (ZIFs), sod-ZIF-1 series, that features two types of six-membered rings (6MRs) with aperture sizes of 3.4 Å and 1.7 Å. By adjusting the configurational entropy, the ratio of these 6MRs can be systematically controlled, which significantly influences adsorptive properties, particularly improving the H2 affinity about 3 times throughout the series. This results in the significant enhancement of retention times in dynamic separation of hydrogen isotopes (D2/H2), even over LNG liquefaction temperature. This approach to entropy-driven pore engineering provides new opportunities for enhancing gas adsorption and separation processes.

Template-Thermally Induced Phase Separation-Assisted Microporous Regulation in Poly(lactic acid) Aerogel for Sustainable Radiative Cooling

Herein, an eco-friendly and degradable poly(lactic acid) aerogel was prepared by combining a poly(ethylene glycol) template material with thermally induced phase separation. Due to the tailored pore size introduced by the template material, the aerogel exhibits high solar reflectance (92.0%), excellent thermal emittance (90.5%), low thermal conductivity (52.0 mW m-1 K-1), and high compressive strength (0.15 MPa). Cooling tests demonstrate that the aerogel can achieve temperature drops of 3.7 °C during the day and of 6.2 °C at night. Furthermore, simulations of building cooling energy systems reveal that the aerogel can reduce energy consumption by 2.2 to 10.2 MJ m-2 per year in various cities, achieving energy savings ranging from 8.2 to 24.3%. Meanwhile, the aerogel cooler demonstrates excellent self-cleaning performance (WCA = 149.1°) and cyclic compression performance. This research will promote the field of passive radiative cooling toward a greener and more sustainable direction.

Multiphoton Excited Fluorescence Imaging over Metal-Organic Frameworks

Multiphoton excited fluorescence (MPEF) imaging has emerged as a powerful tool for visualizing biological processes with high spatial and temporal resolution. Metal-organic frameworks (MOFs), a class of porous materials composed of metal ions or clusters coordinated with organic ligands, have recently gained attention for their unique optical properties and potential applications in MPEF imaging. This review provides a comprehensive overview of the design, synthesis, and applications of multiphoton excited fluorescence imaging using MOFs. We discuss the principles behind the fluorescence behavior of MOFs, explore strategies to enhance their photophysical properties, and showcase their applications in bioimaging. Additionally, we address the current challenges and future prospects in this rapidly evolving field, highlighting the potential of multiphoton excited fluorescence imaging by MOFs for advancing our understanding of complex biological processes.

Rational Design of 7-Azaindole-Based Robust Microporous Hydrogen-Bonded Organic Framework for Gas Sorption

7-Azaindole has been integrated as building block with complementary N-H⋅⋅⋅N hydrogen bonding sites for the synthesis of a tetrahedral molecular tecton, namely tetra(α-carbolin-6-yl)methane, TACM. The self-assembly of this molecule results in a 3D hydrogen-bonded organic framework (HOF). This supramolecular structure constitutes a crystalline microporous material with an extraordinary thermal and chemical robustness. Single crystal X-ray diffraction reveals how the five-fold catenation of diamonoid systems, stabilized by hydrogen bonds and π-π interactions, form an interpenetrated network with monodimensional channels. The structural features of the crystalline material are also observed by transmission electron microscopy (TEM). Additionally, the microporosity of the activated TACM-HOF is characterized by gas sorption (N2, CO2, CH4 and H2) experiments performed at different pressures. A selective adsorption is observed for CO2 uptake and TACM-HOF also presents a good adsorption capacity for H2 among supramolecular organic frameworks.

Construction of Highly Porous and Robust Hydrogen-Bonded Organic Framework for High-Capacity Clean Energy Gas Storage

Development of highly porous and robust hydrogen-bonded organic frameworks (HOFs) for high-pressure methane and hydrogen storage remains a grand challenge due to the fragile nature of hydrogen bonds. Herein, we report a strategy of constructing the double-walled framework to target highly porous and robust HOF (ZJU-HOF-5a) for extraordinary CH4 and H2 storage. ZJU-HOF-5a features a minimized twofold interpenetration with double-walled structure, in which multiple supramolecular interactions are existed between the interpenetrated walls. This structural configuration can notably enhance the framework robustness while maintaining its high porosity, affording one of the highest gravimetric and volumetric surface areas of 3102 m2 g-1 and 1976 m2 cm-3 among the reported HOFs so far. ZJU-HOF-5a thus exhibits an extremely high volumetric H2 uptake of 43.6 g L-1 at 77 K/100 bar and working capacity of 41.3 g L-1 under combined swing conditions (77 K/100 bar→160 K/5 bar), and also impressive methane storage performance with a 5-100 bar working capacity of 187 (or 159) cm3 (STP) cm-3 at 270 K (or 296 K), outperforming most of the reported porous organic materials. Single-crystal X-ray diffraction studies on CH4-loaded ZJU-HOF-5a reveal that abundant supramolecular binding sites combined with ultrahigh porosities account for its high CH4 storage capacities. Combined with high stability, super-hydrophobicity, and easy recovery, ZJU-HOF-5a is placed among the most promising materials for H2 and CH4 storage applications.

Porous MOFs with geometric mismatch between trimers and octatopic pyrene-based ligands for low-temperature methane storage

Natural gas is recognized as a transitional clean energy fuel to address a variety of environmental problems. Identifying porous adsorbents with high-capacity low-temperature methane adsorption performances is crucial for advancing next-generation technologies for efficiently utilizing boil-off gas, inevitablely generated from liquefied natural gas systems. Herein, we synthesized highly porous metal-organic frameworks (MOFs)-TBPP-MOFs with a geometric mismatch strategy by combining seemingly incompatible trinuclear clusters with octatopic pyrene-based ligands. The Cr-TBPP-MOF achieves a high apparent Brunauer-Emmett-Teller (BET) surface area of 3700 m2 g-1 and demonstrates pore volumes of 1.31 cm3 g-1 at P/P0 = 0.9. Consequently, under the LNG-ANG coupling operation conditions, Cr-TBPP-MOF exhibits a high low-temperature methane uptake of 335 cm3 (STP) cm-3 at 159 K and 10 bar with a working capacity of 302 cm3 (STP) cm-3 between 6 bar and 159 K to 5 bar and 298 K, positioning it as a promising candidate material for low-temperature methane adsorption.

Microenvironment modulation of interpenetrating-type hierarchical porous foam carbon by mild-homogeneous activation for H2 storage and CO2 capture under ambient pressure

Currently, carbon-based porous materials for hydrogen (H2) storage and carbon dioxide (CO2) capture are mostly applied at higher pressures (30-300 bar). However, applications for H2 storage and CO2 capture under ambient pressure conditions are significant for the development of portable, household, and miniaturized H2 energy technologies. This demands a higher standard for the interface microenvironment of adsorbents. Derived from polyurethane foams (PUFs) solid waste, the hierarchical porous foam carbon with interpenetrating-type pore structures exhibits high specific surface area (SBET = 1753 m2/g), abundant oxygen and nitrogen functional groups, and a hierarchical nanopore structure (VUltra = 0.232 cm3/g, VMicro = 0.628 cm3/g and VMeso = 0.186 cm3/g) through the mild-homogeneous sonication-assisted activation process. Under the limited adsorption of pore interface microenvironment composed by hierarchical nanopore structure and dipole-induced interaction (H(Ⅱ)-H(Ⅰ)···N/O and O(Ⅱ) = C(Ⅰ) = O(Ⅱ)···N/O), it exhibits an excellent H2 storage density (2.92 wt% at 77 K, 1 bar) and CO2 capture capacity (5.28 mmol/g at 298 K, 1 bar). This research approach can serve as a reference for the dual-functional design of porous foam carbon, and promote the development of adsorption materials for CO2 capture and energy gas storage under ambient conditions.

The Chemistry of Metal-Organic Frameworks for Multicomponent Gas Separation

Adsorbents-based gas separation technologies are regarded as the potential energy-efficient alternatives towards current thermal-driven methods, and the study on multi-component gas separation is essential to deepen our understanding of the adsorbents for practical use. Relative to the ideal two-component mixtures, both the adsorption behavior and separation mechanisms are obviously more complex in multiple gas mixtures due to their close or even overlapped sizes and properties. The emergence of metal-organic frameworks with controllable pore size and pore chemistry provides the platform for the tailor-made pore structure to satisfy the harsh requirements of multi-component gas separation. This minireview highlights the recent advance of multi-component gas separation using metal-organic frameworks, including multiple impurities removal and selective molecular capture. Combining with the typical cases of hydrocarbon separations (C2, C4, and C8), the detailed discussion about the developed strategies (e.g. self-adaptive binding sites, multiple binding spaces, synergistic binding sites, synergistic sorbent separation technology, gate-opening effect, size and thermodynamic combine effect) that are adaptive to different scenarios would be provided. The review will conclude with our perspective on the existing barriers and the future direction of this topic.

Analyzing the Total Attractive Force and Hydrogen Storage on Two-Dimensional MoP2 at Different Temperatures Using a First-Principles Molecular Dynamics Approach

We performed first-principle molecular dynamics (FPMD) calculations to test the total attraction force on a physisorbed molecule at a given temperature and ambient pressure and applied it to the hydrogen storage on the 2D material MoP2. We considered a pristine material and one with 12.5% of Mo vacancies. By optimization, we calculated a gravimetric capacity for pristine MoP2 of 5.72%, with an adsorption energy of -0.13 eV/molecule. We found 6.02% and -0.14 eV/molecule for the defective surface. Next, we applied our approach to determine if the molecular hydrogen physisorption obtained by simple energy optimization exists for a given temperature and ambient pressure. We used this approach to determine the number of molecules adsorbed on the surface at a given temperature. Thus, we conducted a FPMD calculation at temperature T1, using optimization as the initial system configuration. Subsequently, we performed a second FPMD calculation at a temperature T2 (with T2 << T1), using the steady configuration of the first FPMD calculation as the initial configuration. We identified as adsorbed molecules at temperature T1, only those forced back toward the surface at temperature T2 due to kinetic energy loss at the lower temperature. The defective surface gave the best gravimetric capacity, ranging from 5.27% at 300 K to 6.02% at 77 K. The latter met the requirement from the US-DOE, indicating the potential practical application of our research in hydrogen storage.

3D microstructure reconstruction and characterization of porous materials using a cross-sectional SEM image and deep learning

Accurate assessment of the three-dimensional (3D) pore characteristics within porous materials and devices holds significant importance. Compared to high-cost experimental approaches, this study introduces an alternative method: utilizing a generative adversarial network (GAN) to reconstruct a 3D pore microstructure. Unlike some existing GAN models that require 3D images as training data, the proposed model only requires a single cross-sectional image for 3D reconstruction. Using porous ceramic electrode materials as a case study, a comparison between the GAN-generated microstructures and those reconstructed through focused ion beam-scanning electron microscopy (FIB-SEM) reveals promising consistency. The GAN-based reconstruction technique demonstrates its effectiveness by successfully characterizing pore attributes in porous ceramics, with measurements of porosity, pore size, and tortuosity factor exhibiting notable agreement with the results obtained from mercury intrusion porosimetry.

Green Hydrogen Production From Non-Traditional Water Sources: A Sustainable Energy Solution With Hydrogen Storage and Distribution

Green hydrogen development plays an essential role in creating a sustainable and environmentally conscious society while reducing reliance on traditional fossil fuels. Proton Exchange Membrane Water Electrolysers (PEMWEs), are sensitive to water quality, with various impurities impacting their efficiency, the quality of the hydrogen produced, and the device's lifespan. High-purity water is required for PEM electrolyzers; Type II water, which is required for commercial electrolyzers, must have a resistivity greater than 1 MΩ cm, sodium, and chloride concentrations less than 5 μg/L, and total organic carbon (TOC) content less than 50 parts per billion. The majority of electrolyzers operate on freshwater, or total dissolved solids (TDS) <0.5 g/kg, whereas brackish, rainwater, wastewater, and seawater have TDSs of 1-35 g/kg, 0.01-0.15 g/kg, 0.5-2 g/kg, and 35-45 g/kg, respectively. This critical review offers, for the first time, a comprehensive overview of relevant impurities in operating electrolyzers and their impact. The findings of this study indicate that electrolysis-based H2 processes are promising options that contribute to the H2 production capacity but require improvements to produce larger competitive volumes. In addition, the main challenges and opportunities for generating, storing, transporting, and distributing hydrogen, as well as large-scale adoption are discussed.

Highly Dispersed Pd-CeOx Nanoparticles in Zeolite Nanosheets for Efficient CO2-Mediated Hydrogen Storage and Release

Formic acid (FA) dehydrogenation and CO2 hydrogenation to FA/formate represent promising methodologies for the efficient and clean storage and release of hydrogen, forming a CO2-neutral energy cycle. Here, we report the synthesis of highly dispersed and stable bimetallic Pd-based nanoparticles, immobilized on self-pillared silicalite-1 (SP-S-1) zeolite nanosheets using an incipient wetness co-impregnation technique. Owing to the highly accessible active sites, effective mass transfer, exceptional hydrophilicity, and the synergistic effect of the bimetallic species, the optimized PdCe0.2/SP-S-1 catalyst demonstrated unparalleled catalytic performance in both FA dehydrogenation and CO2 hydrogenation to formate. Remarkably, it achieved a hydrogen generation rate of 5974 molH2 molPd -1 h-1 and a formate production rate of 536 molformate molPd -1 h-1 at 50 °C, surpassing most previously reported heterogeneous catalysts under similar conditions. Density functional theory calculations reveal that the interfacial effect between Pd and cerium oxide clusters substantially reduces the activation barriers for both reactions, thereby increasing the catalytic performance. Our research not only showcases a compelling application of zeolite nanosheet-supported bimetallic nanocatalysts in CO2-mediated hydrogen storage and release but also contributes valuable insights towards the development of safe, efficient, and sustainable hydrogen technologies.

Triazine-Carbazole-Based Covalent Organic Frameworks as Efficient Heterogeneous Photocatalysts for the Oxidation of N-aryltetrahydroisoquinolines

Covalent organic frameworks (COFs) have attracted growing interests as new material platform for a range of applications. In this study, a triazine-carbazole-based covalent organic framework (COF-TCZ) was designed as highly porous material with conjugated donor-acceptor networks, and feasibly synthesized by the Schiff condensation of 4,4',4''-(1,3,5-triazine-2,4,6-triyl)tr ianiline (TAPB) and 9-(4-formylphenyl)-9H-carbazole-3,6-dicarbaldehyde (CZTA) under the solvothermal condition. Considering the effect of linkage, the imine-linked COF-TCZ was further oxidized to obtain an amide-linked covalent organic framework (COF-TCZ-O). The as-synthesized COFs show high crystallinity, good thermal and chemical stability, and excellent photoactive properties. Two π-conjugated triazine-carbazole-based COFs with tunable linkages are beneficial for light-harvesting capacity and charge separation efficiency, which are empolyed as photocatalysts for the oxidation reaction of N-aryltetrahydroisoquinoline. The COFs catalyst systems exhibit the outstanding photocatalytic performance with high conversion, photostability and recyclability. Photoelectrochemical tests were employed to examine the behavior of photogenerated charge carriers in photo-illumination system. The control experiments provide further insights into the nature of photocatalysis. In addition, the current research also provided a valuable approach for developing photofunctional COFs to meet challenge in achieving the great potential of COFs materials in organic conversion.

Recent advances and perspectives on intercalation layered compounds part 1: design and applications in the field of energy

Herein, initially, we present a general overview of the global financial support for chemistry devoted to materials science, specifically intercalation layered compounds (ILCs). Subsequently, the strategies to synthesise these host structures and the corresponding guest-host hybrid assemblies are exemplified on the basis of some families of materials, including pillared clays (PILCs), porous clay heterostructures (PCHs), zirconium phosphate (ZrP), layered double hydroxides (LDHs), graphite intercalation compounds (GICs), graphene-based materials, and MXenes. Additionally, a non-exhaustive survey on their possible application in the field of energy through electrochemical storage, mostly as electrode materials but also as electrolyte additives, is presented, including lithium technologies based on lithium ion batteries (LIBs), and beyond LiBs with a focus on possible alternatives such XIBs (X = Na (NIB), K (KIB), Al (AIB), Zn (ZIB), and Cl (CIB)), reversible Mg batteries (RMBs), dual-ion batteries (DIBs), Zn-air and Zn-sulphur batteries and supercapacitors as well as their relevance in other fields related to (opto)electronics. This selective panorama should help readers better understand the reason why ILCs are expected to meet the challenge of tomorrow as electrode materials.

Decoding the Biomimetic Mineralization of Metal-Organic Frameworks in Water

This study unveils the "green" metal-organic framework (MOF) structuring mechanism by decoding proton transfer in water during ZIF-8 synthesis. Combining in situ small- to wide-angle X-ray scattering, multiscale simulations, and quantum calculations, we reveal that the ZIF-8 early-stage nucleation and crystallization process in aqueous solution unfolds in three distinct stages. In stage I, imidazole ligands replace water in zinc-water cages, triggering an "acidity flip" that promotes proton transfer. This leads to the assembly of structures from single zinc ions to 3D amorphous cluster nuclei. In stage II, amorphous nuclei undergo a critical transformation, evolving into crystalline nuclei and subsequently forming mesoscale-ordered structures and crystallites. The process proceeds until the amorphous precursors are completely consumed, with the transformation kinetics governed by an energy barrier that determines the rate-limiting step. In stage III, stable crystallite nanoparticles form in solution, characterized by a temperature-dependent thermal equilibrium of molecular interactions at the crystal-solution interface. Beyond these core advancements, we explore the influence of encapsulated pepsin and nonencapsulated lysozyme on ZIF-8 formation, finding that their amino acid proton transfer capacity and concentration influence the resulting biomolecule-MOF composite's shape and encapsulation efficiency. The findings contribute to understanding the molecular mechanisms behind biomimetic mineralization and have potential implications for engineering proteins within amorphous MOF nuclei as protein embryo growth sites.

Introducing Noble Gas as Space Holder under High Pressure to Design Porous Titanium Carbides with Open Metal Sites for Hydrogen Storage at Near-Ambient Conditions

It has been a long-standing challenge to develop high-performance solid-state hydrogen storage materials operated under near-ambient conditions. In this work, we propose a new strategy of using noble gases for space holding to design porous titanium carbides with abundant open metal sites for hydrogen storage. By using machine learning and graph theory-assisted universal structure searching methods, we obtain 28 porous titanium carbides from three precursors (TiC dimer, C atom, and Kr atom) under 30 GPa of pressure. The stability and hydrogen storage performance of the resulting structures are further assessed and validated through density function theory and grand canonical Monte Carlo simulations with a DFT-fitted force field. Finally, p-TiC2 is identified as a promising quasi-molecular hydrogen storage material with capacity of 4.0 wt % and 106.0 g/L at 230 K and 16 bar.

Recent Advances in Reversible Liquid Organic Hydrogen Carrier Systems: From Hydrogen Carriers to Catalysts

Liquid organic hydrogen carriers (LOHCs) have gained significant attention for large-scale hydrogen storage due to their remarkable gravimetric hydrogen storage capacity (HSC) and compatibility with existing oil and gas transportation networks for long-distance transport. However, the practical application of reversible LOHC systems has been constrained by the intrinsic thermodynamic properties of hydrogen carriers and the performances of associated catalysts in the (de)hydrogenation cycles. To overcome these challenges, thermodynamically favored carriers, high-performance catalysts, and catalytic procedures need to be developed. Here, significant advances in recent years have been summarized, primarily centered on regular LOHC systems catalyzed by homogeneous and heterogeneous catalysts, including dehydrogenative aromatization of cycloalkanes to arenes and N-heterocyclics to N-heteroarenes, as well as reverse hydrogenation processes. Furthermore, with the development of metal complexes for dehydrogenative coupling, a new family of reversible LOHC systems based on alcohols is described that can release H2 under relatively mild conditions. Finally, views on the next steps and challenges in the field of LOHC technology are provided, emphasizing new resources for low-cost hydrogen carriers, high-performance catalysts, catalytic technologies, and application scenarios.

Constructing Isoreticular Metal-Organic Frameworks by Silver-Carbon Bonds

The incorporation of new coordinate bonds and the development of universal methods for new structures have always been of major interest in metal-organic framework (MOF) research. The poor reversibility makes metal-carbon (M-C) bonds a great challenge to adopt as linkages to construct crystalline MOFs. Herein, three isoreticular microcrystalline MOFs connected by silver-carbon (Ag-C) bonds are presented for the first time and named AgC-MOFs. Their structures contain a double coordination mode (σ and π) between Ag(I) and alkynyl. The three AgC-MOFs all exhibit three-dimensional (3D) frameworks with uniform one-dimensional (1D) hexagonal channels, and the pore width could be tuned from 1.1 to 1.8 nm. The construction of crystalline MOFs using poorly reversible Ag-C coordinate bonds extends the nexuses for the MOF structure and lights up more possibilities for the systematic design of MOFs.

MXenes and MXene-Based Metal Hydrides for Solid-State Hydrogen Storage: A Review

Hydrogen-driven energy is fascinating among the everlasting energy sources, particularly for stationary and onboard transportation applications. Efficient hydrogen storage presents a key challenge to accomplishing the sustainability goals of hydrogen economy. In this regard, solid-state hydrogen storage in nanomaterials, either physically or chemically adsorbed, has been considered a safe path to establishing sustainability goals. Though metal hydrides have been extensively explored, they fail to comply with the set targets for practical utilization. Recently, MXenes, both in bare form and hybrid state with metal hydrides, have proven their flair in ascertaining the hydrides' theoretical and experimental hydrogen storage capabilities far beyond the fancy materials and current state-of-the-art technologies. This review encompasses the significant accomplishments achieved by MXenes (primarily in 2019-2024) for enhancing the hydrogen storage performance of various metal hydride materials such as MgH2, AlH3, Mg(BH4)2, LiBH4, alanates, and composite hydrides. It also discusses the bottlenecks of metal hydrides for hydrogen storage, the potential use of MXenes hybrids, and their challenges, such as reversibility, H2 losses, slow kinetics, and thermodynamic barriers. Finally, it concludes with a detailed roadmap and recommendations for mechanistic-driven future studies propelling toward a breakthrough in solid material-driven hydrogen storage using cost-effective, efficient, and long-lasting solutions.

Hydrogen Production from Ammonia Decomposition: A Mini-Review of Metal Oxide-Based Catalysts

Efficient hydrogen storage and transportation are crucial for the sustainable development of human society. Ammonia, with a hydrogen storage density of up to 17.6 wt%, is considered an ideal energy carrier for large-scale hydrogen storage and has great potential for development and application in the "hydrogen economy". However, achieving ammonia decomposition to hydrogen under mild conditions is challenging, and therefore, the development of suitable catalysts is essential. Metal oxide-based catalysts are commonly used in the industry. This paper presents a comprehensive review of single and composite metal oxide catalysts for ammonia decomposition catalysis. The focus is on analyzing the conformational relationships and interactions between metal oxide carriers and active metal sites. The aim is to develop new and efficient metal oxide-based catalysts for large-scale green ammonia decomposition.

Computational Simulations of Metal-Organic Frameworks to Enhance Adsorption Applications

Metal-organic frameworks (MOFs), renowned for their exceptional porosity and crystalline structure, stand at the forefront of gas adsorption and separation applications. Shortly after their discovery through experimental synthesis, computational simulations quickly become an important method in broadening the use of MOFs by offering deep insights into their structural, functional, and performance properties. This review specifically addresses the pivotal role of molecular simulations in enlarging the molecular understanding of MOFs and enhancing their applications, particularly for gas adsorption. After reviewing the historical development and implementation of molecular simulation methods in the field of MOFs, high-throughput computational screening (HTCS) studies used to unlock the potential of MOFs in CO2 capture, CH4 storage, H2 storage, and water harvesting are visited and recent advancements in these adsorption applications are highlighted. The transformative impact of integrating artificial intelligence with HTCS on the prediction of MOFs' performance and directing the experimental efforts on promising materials is addressed. An outlook on current opportunities and challenges in the field to accelerate the adsorption applications of MOFs is finally provided.

Porous organic crystals crosslinked by free-radical reactions

Two hydrogen-bonded crosslinked organic frameworks (HCOFs) were synthesized via free radical reactions utilizing butadiene and isoprene as crosslinkers. These HCOFs exhibit high crystallinity, enabling detailed structural characterization via single-crystal X-ray diffraction analysis. Subsequently, one of the olefin-rich HCOFs was converted to a hydroxylated framework through hydroboration-oxidation while maintaining the high crystallinity.

Poly(ionic liquid)-Flocculated Chlorella Loading Bactericidal and Antioxidant Hydrogel as a Biological Hydrogen Therapy for Diabetic Wound Dressing

Infection and oxidative stress seriously hinder the healing of diabetic wounds, resulting in various serious health and clinical problems. Herein, a sustainable biological hydrogen (H2)-producing hyaluronic acid-based hydrogel patch (HAP-Chl) was constructed by loading an imidazolium-based poly(ionic liquid) (PIL) flocculated live Chlorella as a diabetic wound dressing. The PIL can flocculate Chlorella through electrostatic interactions between PIL and Chlorella to form Chlorella agglomerates, endowing the Chlorella in the central agglomerates with the ability to continuously produce H2 for 24 h under mild conditions. Combining the membrane disruption-related bactericidal mechanism of PIL and the antioxidant properties of the produced H2, HAP-Chl was determined to be antibacterial and antioxidant. In addition to exhibiting biocompatible and nontoxic activities, subsequent Staphylococcus aureus-infected chronic wound studies revealed that HAP-Chl is capable of promoting the healing of chronic wounds by effectively killing bacteria, reducing extensive ROS, relieving inflammation, and promoting the deposition of mature collagen and angiogenesis. This study provides a new strategy for constructing an in situ sustainable H2-producing hydrogel, enabling the formation of novel antibacterial and antioxidant material platforms with potential for wound dressing applications.

Enhancing sorption kinetics by oriented and single crystalline array-structured ZSM-5 film on monoliths

To enhance the reaction kinetics without sacrificing activity in porous materials, one potential solution is to utilize the anisotropic distribution of pores and channels besides enriching active centers at the reactive surfaces. Herein, by designing a unique distribution of oriented pores and single crystalline array structures in the presence of abundant acid sites as demonstrated in the ZSM-5 nanorod arrays grown on monoliths, both enhanced dynamics and improved capacity are exhibited simultaneously in propene capture at low temperature within a short duration. Meanwhile, the ZSM-5 array also helps mitigate the long-chain HCs and coking formation due to the enhanced diffusion of reactants in and reaction products out of the array structures. Further integrating the ZSM-5 array with Co3O4 nanoarray enables comprehensive propene removal throughout a wider temperature range. The array structured film design could offer energy-efficient solutions to overcome both sorption and reaction kinetic restrictions in various solid porous materials for various energy and chemical transformation applications.

Hydrogen storage in M(BDC)(TED)0.5 metal-organic framework: physical insights and capacities

Finding renewable energy sources to replace fossil energy has been an essential demand in recent years. Hydrogen gas has been becoming a research hotspot for its clean and free-carbon energy. However, hydrogen storage technology is challenging for mobile and automotive applications. Metal-organic frameworks (MOFs) have emerged as one of the most advanced materials for hydrogen storage due to their exceptionally high surface area, ultra-large and tuneable pore size. Recently, computer simulations allowed the designing of new MOF structures with significant hydrogen storage capacity. However, no studies are available to elucidate the hydrogen storage in M(BDC)(TED)0.5, where M = metal, BDC = 1,4-benzene dicarboxylate, and TED = triethylenediamine. In this report, we used van der Waals-dispersion corrected density functional theory and grand canonical Monte Carlo methods to explore the electronic structure properties, adsorption energies, and gravimetric and volumetric hydrogen loadings in M(BDC)(TED)0.5 (M = Mg, V, Co, Ni, and Cu). Our results showed that the most favourable adsorption site of H2 in M(BDC)(TED)0.5 is the metal cluster-TED intersection region, in which Ni offers the strongest binding strength with the adsorption energy of -16.9 kJ mol-1. Besides, the H2@M(BDC)(TED)0.5 interaction is physisorption, which mainly stems from the contribution of the d orbitals of the metal atoms for M = Ni, V, Cu, and Co and the p orbitals of the O, C, N atoms for M = Mg interacting with the σ* state of the adsorbed hydrogen molecule. Noticeably, the alkaline-earth metal Mg strongly enhanced the specific surface area and pore size of the M(BDC)(TED)0.5 MOF, leading to an enormous increase in hydrogen storage with the highest absolute (excess) gravimetric and volumetric uptakes of 1.05 (0.36) wt% and 7.47 (2.59) g L-1 at 298 K and 7.42 (5.80) wt% and 52.77 (41.26) g L-1 at 77 K, respectively. The results are comparable to the other MOFs found in the literature.

Advances and Prospects of Nanomaterials for Solid-State Hydrogen Storage

Hydrogen energy, known for its high energy density, environmental friendliness, and renewability, stands out as a promising alternative to fossil fuels. However, its broader application is limited by the challenge of efficient and safe storage. In this context, solid-state hydrogen storage using nanomaterials has emerged as a viable solution to the drawbacks of traditional storage methods. This comprehensive review delves into the recent advancements in nanomaterials for solid-state hydrogen storage, elucidating the fundamental principles and mechanisms, highlighting significant material systems, and exploring the strategies of surface and interface engineering alongside catalytic enhancement. We also address the primary challenges and provide future perspectives on the development of nanomaterial-based hydrogen storage technologies. Key discussions include the role of nanomaterial size effects, surface modifications, nanocomposites, and nanocatalysts in optimizing storage performance.

Exploring Defect-Engineered Metal-Organic Frameworks with 1,2,4-Triazolyl Isophthalate and Benzoate Linkers

Synthesis and characterization of DEMOFs (defect-engineered metal-organic frameworks) with coordinatively unsaturated sites (CUSs) for gas adsorption, catalysis, and separation are reported. We use the mixed-linker approach to introduce defects in Cu2-paddle wheel units of MOFs [Cu2(Me-trz-ia)2] by replacing up to 7% of the 3-methyl-triazolyl isophthalate linker (1L2-) with the "defective linker" 3-methyl-triazolyl m-benzoate (2L-), causing uncoordinated equatorial sites. PXRD of DEMOFs shows broadened reflections; IR and Raman analysis demonstrates only marginal changes as compared to the regular MOF (ReMOF, without a defective linker). The concentration of the integrated defective linker in DEMOFs is determined by 1H NMR and HPLC, while PXRD patterns reveal that DEMOFs maintain phase purity and crystallinity. Combined XPS (X-ray photoelectron spectroscopy) and cw EPR (continuous wave electron paramagnetic resonance) spectroscopy analyses provide insights into the local structure of defective sites and charge balance, suggesting the presence of two types of defects. Notably, an increase in CuI concentration is observed with incorporation of defective linkers, correlating with the elevated isosteric heat of adsorption (ΔHads). Overall, this approach offers valuable insights into the creation and evolution of CUSs within MOFs through the integration of defective linkers.

Structural Design and Energy and Environmental Applications of Hydrogen-Bonded Organic Frameworks: A Systematic Review

Hydrogen-bonded organic frameworks (HOFs) are emerging porous materials that show high structural flexibility, mild synthetic conditions, good solution processability, easy healing and regeneration, and good recyclability. Although these properties give them many potential multifunctional applications, their frameworks are unstable due to the presence of only weak and reversible hydrogen bonds. In this work, the development history and synthesis methods of HOFs are reviewed, and categorize their structural design concepts and strategies to improve their stability. More importantly, due to the significant potential of the latest HOF-related research for addressing energy and environmental issues, this work discusses the latest advances in the methods of energy storage and conversion, energy substance generation and isolation, environmental detection and isolation, degradation and transformation, and biological applications. Furthermore, a discussion of the coupling orientation of HOF in the cross-cutting fields of energy and environment is presented for the first time. Finally, current challenges, opportunities, and strategies for the development of HOFs to advance their energy and environmental applications are discussed.

High Hydrogen Storage in Trigonal Prismatic Monomer-Based Highly Porous Aromatic Frameworks

Hydrogen storage is crucial in the shift toward a carbon-neutral society, where hydrogen serves as a pivotal renewable energy source. Utilizing porous materials can provide an efficient hydrogen storage solution, reducing tank pressures to manageable levels and circumventing the energy-intensive and costly current technological infrastructure. Herein, two highly porous aromatic frameworks (PAFs), C-PAF and Si-PAF, prepared through a Yamamoto C─C coupling reaction between trigonal prismatic monomers, are reported. These PAFs exhibit large pore volumes and Brunauer-Emmett-Teller areas, 3.93 cm3 g-1 and 4857 m2 g-1 for C-PAF, and 3.80 cm3 g-1 and 6099 m2 g-1 for Si-PAF, respectively. Si-PAF exhibits a record-high gravimetric hydrogen delivery capacity of 17.01 wt% and a superior volumetric capacity of 46.5 g L-1 under pressure-temperature swing adsorption conditions (77 K, 100 bar → 160 K, 5 bar), outperforming benchmark hydrogen storage materials. By virtue of the robust C─C covalent bond, both PAFs show impressive structural stabilities in harsh environments and unprecedented long-term durability. Computational modeling methods are employed to simulate and investigate the structural and adsorption properties of the PAFs. These results demonstrate that C-PAF and Si-PAF are promising materials for efficient hydrogen storage.

Freeze-Casting of Alumina and Permeability Analysis Based on a 3D Microstructure Reconstructed Using Generative Adversarial Networks

In this study, alumina ceramics with hierarchical pores were successfully fabricated using freeze casting. Experimental studies show that both the solid loading of the slurry and the thermal insulation layer at the interface of the slurry and cooling plate can influence the pore characteristics of cast samples. In order to examine the pore characteristics and evaluate the permeability of the freeze-cast samples fabricated under different conditions, a generative adversarial network (GAN) method was employed to reconstruct the three-dimensional (3D) microstructure from two-dimensional (2D) scanning electron microscopy (SEM) images of the samples. Furthermore, GAN 3D reconstruction was validated against X-ray tomography 3D reconstruction results. Based on the GAN reconstructed microstructures, the permeability and pore distribution of the various samples were analyzed. The sample cast with 35 wt.% solid loading shows an optimal permeability.

Mg-MOF-74 Derived Defective Framework for Hydrogen Storage at Above-Ambient Temperature Assisted by Pt Catalyst

Metal-organic frameworks (MOFs) are promising candidates for room-temperature hydrogen storage materials after modification, thanks to their ability to chemisorb hydrogen. However, the hydrogen adsorption strength of these modified MOFs remains insufficient to meet the capacity and safety requirements of hydrogen storage systems. To address this challenge, a highly defective framework material known as de-MgMOF is prepared by gently annealing Mg-MOF-74. This material retains some of the crystal properties of the original Mg-MOF-74 and exhibits exceptional hydrogen storage capacity at above-ambient temperatures. The MgO5 knots around linker vacancies in de-MgMOF can adsorb a significant amount of dissociated and nondissociated hydrogen, with adsorption enthalpies ranging from -22.7 to -43.6 kJ mol-1, indicating a strong chemisorption interaction. By leveraging a spillover catalyst of Pt, the material achieves a reversible hydrogen storage capacity of 2.55 wt.% at 160 °C and 81 bar. Additionally, this material offers rapid hydrogen uptake/release, stable cycling, and convenient storage capabilities. A comprehensive techno-economic analysis demonstrates that this material outperforms many other hydrogen storage materials at the system level for on-board applications.

Biomimicking covalent organic frameworks nanocomposite coating for integrated enhanced anticorrosion and antifouling properties of a biodegradable magnesium stent

The utilization of biodegradable magnesium (Mg) alloys in the fabrication of temporary non-vascular stents is an innovative trend in biomedical engineering. However, the heterogeneous degradation profiles of these biomaterials, together with potential bacterial colonization that could precipitate infectious or stenotic complications, are critical obstacles precluding their widespread clinical application. In pursuit of overcoming these limitations, this study applies the principles of biomimicry, particularly the hydrophobic and anti-fouling characteristics of lotus leaves, to pioneer the creation of nanocomposite coatings. These coatings integrate poly-trimethylene carbonate (PTMC) with covalent organic frameworks (COFs), to modify the stent's surface property. The strategic design of the coating's topography, porosity, and self-polishing capabilities collectively aims to decelerate degradation processes and minimize biological adhesion. The protective qualities of the coatings were substantiated through rigorous testing in both in vitro dynamic bile tests and in vivo New Zealand rabbit choledochal models. Empirical findings from these trials confirmed that the implementation of COF-based nanocomposite coatings robustly fortifies Mg implantations, conferring heightened resistance to both biocorrosion and biofouling as well as improved biocompatibility within bodily environments. The outcomes of this research elucidate a comprehensive framework for the multifaceted strategies against stent corrosion and fouling, thereby charting a visionary pathway toward the systematic conception of a new class of reliable COF-derived surface modifications poised to amplify the efficacy of Mg-based stents. STATEMENT OF SIGNIFICANCE: Biodegradable magnesium (Mg) alloys are widely utilized in temporary stents, though their rapid degradation and susceptibility to bacterial infection pose significant challenges. Our research has developed a nanocomposite coating inspired by the lotus, integrating poly-trimethylene carbonate with covalent organic frameworks (COF). The coating achieved self-polishing property and optimal surface energy on the Mg substrate, which decelerates stent degradation and reduces biofilm formation. Comprehensive evaluations utilizing dynamic bile simulations and implantation in New Zealand rabbit choledochal models reveal that the coating improves the durability and longevity of the stent. The implications of these findings suggest the potential COF-based Mg alloy stent surface treatments and a leap forward in advancing stent performance and endurance in clinical applications.

Turbulent Properties of Stationary Flows in Porous Media

In this study, we investigate the flow dynamics in a fixed bed of hydrogel beads using particle tracking velocimetry to compute the velocity field in the middle of the bed for moderate Reynolds numbers (Re=[124,169,203,211]). We discover that even though the flow is stationary at the larger scales, it exhibits complex multiscale spatial dynamics reminiscent of those observed in classical turbulence. We find evidence of the presence of an inertial range and a direct energy cascade, and are able to obtain a value for a "porous" Kolmogorov constant of C_{2}=3.1±0.3. This analogy with turbulence opens up new possibilities for understanding mixing and global transport properties in porous media.

Sc-Modified C3N4 Nanotubes for High-Capacity Hydrogen Storage: A Theoretical Prediction

Utilizing hydrogen as a viable substitute for fossil fuels requires the exploration of hydrogen storage materials with high capacity, high quality, and effective reversibility at room temperature. In this study, the stability and capacity for hydrogen storage in the Sc-modified C3N4 nanotube are thoroughly examined through the application of density functional theory (DFT). Our finding indicates that a strong coupling between the Sc-3d orbitals and N-2p orbitals stabilizes the Sc-modified C3N4 nanotube at a high temperature (500 K), and the high migration barrier (5.10 eV) between adjacent Sc atoms prevents the creation of metal clusters. Particularly, it has been found that each Sc-modified C3N4 nanotube is capable of adsorbing up to nine H2 molecules, and the gravimetric hydrogen storage density is calculated to be 7.29 wt%. It reveals an average adsorption energy of -0.20 eV, with an estimated average desorption temperature of 258 K. This shows that a Sc-modified C3N4 nanotube can store hydrogen at low temperatures and harness it at room temperature, which will reduce energy consumption and protect the system from high desorption temperatures. Moreover, charge donation and reverse transfer from the Sc-3d orbital to the H-1s orbital suggest the presence of the Kubas effect between the Sc-modified C3N4 nanotube and H2 molecules. We draw the conclusion that a Sc-modified C3N4 nanotube exhibits exceptional potential as a stable and efficient hydrogen storage substrate.

High Internal Phase Emulsion for Constructing Chiral Helical Polymer-Based Circularly Polarized Luminescent Porous Materials

Polymerized high internal phase emulsions (polyHIPEs) with circularly polarized luminescence (CPL), as an interesting class of porous materials, are of great significance for the development of CPL porous materials but have not been reported so far. Herein, we report the construction of polyHIPE-based CPL porous materials, taking advantage of an adsorption strategy. The pristine polyHIPEs constructed by chiral helical polymers, which acted as a chiral microenvironment, were fabricated by coordination polymerization of chiral acetylene monomers (R/S-SA) using HIPEs as templates. Achiral fluorescent small molecules were dispersed in the pores of the 3D porous organic chiral polymer matrix provided by polyHIPEs through the adsorption strategy, and CPL-active porous materials with blue, cyan, and green emissions were constructed using a fluorescence-selective absorption mechanism that does not rely on chirality transfer at the molecular level. The maximum luminescence dissymmetry factor (glum) value was -2.6 × 10-2. This work establishes a new and simple way for developing CPL porous materials.

Exploring the Role of Ligand Connectivity in MOFs Mechanical Stability: The Case of MIL-100(Cr)

The key parameters governing the mechanical stability of highly porous materials such as metal-organic frameworks (MOFs) are yet to be clearly understood. This study focuses on the role of the linker connectivity by investigating the mechanical stability of MIL-100(Cr), a mesoporous MOF with a hierarchical structure and a tritopic linker, and comparing it to MIL-101(Cr) having instead a ditopic linker. Using synchrotron X-ray diffraction and infrared spectroscopy, we investigate the high-pressure behavior of MIL-100(Cr) with both solid and fluid pressure transmitting media (PTM). In the case of a solid medium, MIL-100(Cr) undergoes amorphization at about 0.6 GPa, while silicone oil as a PTM delays amorphization until 12 GPa due to the fluid penetration into the pores. Both of these values are considerably higher than those of MIL-101(Cr). MIL-100(Cr) also exhibits a bulk modulus almost ten times larger than that of MIL-101(Cr). This set of results coherently proves the superior stability of MIL-100(Cr) under compression. We ascribe this to the higher connectivity of the organic linker in MIL-100(Cr), which enhances its interconnection between the metal nodes. These findings shed light on the importance of linker connectivity in the mechanical stability of MOFs, a relevant contribution to the quest for designing more robust MOFs.

Expanding the Reticular Chemistry Building Block Library toward Highly Connected Nets: Ultraporous MOFs Based on 18-Connected Ternary, Trigonal Prismatic Superpolyhedra

The chemistry of metal-organic frameworks (MOFs) continues to expand rapidly, providing materials with diverse structures and properties. The reticular chemistry approach, where well-defined structural building blocks are combined together to form crystalline open framework solids, has greatly accelerated the discovery of new and important materials. However, its full potential toward the rational design of MOFs relies on the availability of highly connected building blocks because these greatly reduce the number of possible structures. Toward this, building blocks with connectivity greater than 12 are highly desirable but extremely rare. We report here the discovery of novel 18-connected, trigonal prismatic, ternary building blocks (tbb's) and their assembly into unique MOFs, denoted as Fe-tbb-MOF-x (x: 1, 2, 3), with hierarchical micro- and mesoporosity. The remarkable tbb is an 18-c supertrigonal prism, with three points of extension at each corner, consisting of triangular (3-c) and rectangular (4-c) carboxylate-based organic linkers and trigonal prismatic [Fe3(μ3-Ο)(-COO)6]+ clusters. The tbb's are linked together by an 18-c cluster made of 4-c ligands and a crystallographically distinct Fe3(μ3-Ο) trimer, forming overall a 3-D (3,4,4,6,6)-c five nodal net. The hierarchical, highly porous nature of Fe-tbb-MOF-x (x: 1, 2, 3) was confirmed by recording detailed sorption isotherms of Ar, CH4, and CO2 at 87, 112, and 195 K, respectively, revealing an ultrahigh BET area (4263-4847 m2 g-1) and pore volume (1.95-2.29 cm3 g-1). Because of the observed ultrahigh porosities, the H2 and CH4 storage properties of Fe-tbb-MOF-x were investigated, revealing well-balanced high gravimetric and volumetric deliverable capacities for cryoadsorptive H2 storage (11.6 wt %/41.4 g L-1, 77 K/100 bar-160 K/5 bar), as well as CH4 storage at near ambient temperatures (367 mg g-1/160 cm3 STP cm-3, 5-100 bar at 298 K), placing these materials among the top performing MOFs. The present work opens new directions to apply reticular chemistry for the construction of novel MOFs with tunable porosities based on contracted or expanded tbb analogues.

A minireview on covalent organic frameworks as stationary phases in chromatography

Advances in the design of novel porous materials open new avenues for the development of chromatographic solid stationary phases. Covalent organic frameworks (COFs) are promising candidates in this context due to their remarkable structural versatility and exceptional chemical and textural properties. In this minireview, we summarize the main strategies followed in recent years to apply these materials as stationary phases for chromatographic separations. We also comment on the perspectives of this new research field and potential directions to expand the applicability and implementation of COF stationary phases in analytical systems.

DNA-Directed Assembly of Hierarchical MOF-Cellulose Nanofiber Microbioreactors with "Branch-Fruit" Structures

Assembling metal-organic frameworks (MOFs) into ordered multidimensional porous superstructures promises the encapsulation of enzymes for heterogeneous biocatalysts. However, the full potential of this approach has been limited by the poor stability of enzymes and the uncontrolled assembly of MOF nanoparticles onto suitable supports. In this study, a novel and exceptionally robust Ni-imidazole-based MOF was synthesized in water at room temperature, enabling in situ enzyme encapsulation. Based on this MOF platform, we developed a DNA-directed assembly strategy to achieve the uniform placement of MOF nanoparticles onto bacterial cellulose nanofibers, resulting in a distinctive "branch-fruit" structure. The resulting hybrid materials demonstrated remarkable versatility across various catalytic systems, accommodating natural enzymes, nanoenzymes, and multienzyme cascades, thus showcasing enormous potential as universal microbioreactors. Furthermore, the hierarchical composites facilitated rapid diffusion of the bulky substrate while maintaining the enzyme stability, with ∼3.5-fold higher relative activity compared to the traditional enzyme@MOF immobilized in bacterial cellulose nanofibers.

Establishing ZIF-8 as a reference material for hydrogen cryoadsorption: An interlaboratory study

Hydrogen storage by cryoadsorption on porous materials has the advantages of low material cost, safety, fast kinetics, and high cyclic stability. The further development of this technology requires reliable data on the H2 uptake of the adsorbents, however, even for activated carbons the values between different laboratories show sometimes large discrepancies. So far no reference material for hydrogen cryoadsorption is available. The metal-organic framework ZIF-8 is an ideal material possessing high thermal, chemical, and mechanical stability that reduces degradation during handling and activation. Here, we distributed ZIF-8 pellets synthesized by extrusion to 9 laboratories equipped with 15 different experimental setups including gravimetric and volumetric analyzers. The gravimetric H2 uptake of the pellets was measured at 77 K and up to 100 bar showing a high reproducibility between the different laboratories, with a small relative standard deviation of 3-4 % between pressures of 10-100 bar. The effect of operating variables like the amount of sample or analysis temperature was evaluated, remarking the calibration of devices and other correction procedures as the most significant deviation sources. Overall, the reproducible hydrogen cryoadsorption measurements indicate the robustness of the ZIF-8 pellets, which we want to propose as a reference material.