Achieving carbon neutrality through reducing amounts of atmospheric carbon dioxide (CO₂) has emerged as an urgent global challenge in the fields of environmental science and sustainable development. Among the emerging mitigation strategies, electrocatalytic CO₂ reduction reaction (ECRR) stands out for its capacity to convert CO₂ into high-valued chemicals or energy-dense fuels, providing a promising approach for reducing CO₂ emissions and converting renewable electric energy into chemical energy. Metal-organic frameworks (MOFs) represent a promising class of catalysts for ECRR, owing to their intrinsic structural advantages—including well-defined porosity and atomic-level structural tunability—which collectively enhance CO₂ mass transport and adsorption, and enable systematic investigation of structure-activity relationship as well as reaction mechanism. In particular, MOFs constructed from nitrogen-containing heterocyclic ligands have garnered remarkable research interest, attributed to their superior features such as structural flexibility, abundant catalytic active sites and suitable stability. This review outlines the fundamental physicochemical properties and advanced characterization techniques for the nitrogen-containing heterocyclic ligand-based MOFs. Then recent advances in the application of such MOFs to ECRR were summarized categorizing by the nitrogen-containing moieties, namely imidazolyl-, pyrazolyl-, triazolyl- and tetrazolyl-based ligands. Finally, this review analyzed the critical challenges impeding the practical application of nitrogen-containing heterocyclic ligand-based MOFs in ECRR, including intrinsic electronic conductivity limitations, structural and electrochemical stability under prolonged operational conditions, integration of electrolyzer systems and mechanistic ambiguities arising from dynamic structural evolution during the ECRR. On this basis, prospects for future research directions are presented.

Chiral metal-organic frameworks, as a class of advanced chiral materials with highly tunable structures, exhibit promising applications in the fields of medicine, biology, optics and so on. Recently, significant progresses of chiral metal- organic frameworks have been achieved. However, with the interdisciplinary intersection and integration of relevant research and various fields, new challenges have emerged, such as the efficient synthesis of chiral ligands and chiral metal-organic frameworks, their stability in potential application scenarios, and the molecular-level mechanisms underlying their enantioselective applications. This review discusses the direct synthetic strategies of chiral metal-organic frameworks (direct synthesis based on chiral ligands, spontaneous resolution from achiral ligands, chiral template induction, and chiral defect engineering) as well as post-synthetic modification strategies (post-modification of metal ion nodes/organic ligands and post-modification of functional guests). Furthermore, this review summarizes the research advances of chiral metal-organic frameworks in enantioselective sensing, enantiomers separation, asymmetric catalysis, and chiral optics in recent five years, and provides an outlook in the future development of this field.

Due to the high natural abundance of host metal, exploration of aluminum-based metal-organic frameworks (Al-MOFs) provides a new approach to construct economical-friendly functional materials. However, compared with other metal-based MOFs, the fast hydrolysis kinetic of Al^3＋ leads to great difficulty in crystallization, limiting their investigations in structure and host-guest chemistry. As the understanding towards the hydrolysis of Al^3＋ deepens, recently the development of Al-MOFs boomed, thus an up-to-date summary of this area is of great importance. Based on this, this review provides a detailed summary of the synthetic methods, structural diversity, and applications in host-guest chemistry of Al-MOFs. Regarding synthetic methods, in addition to the traditional solvothermal method, the emerging microwave-assisted synthesis and electrochemical synthesis are included as well. In terms of structural diversity, all secondary building units (SBUs) reported in Al-MOFs to date are classified and summarized. Starting from these SBUs, the derived Al-MOF structures reported after 2023 are discussed in detail. Moreover, the host-guest chemistry of Al-MOFs is highlighted. By categorizing the guest molecules, this review summarizes the corresponding absorption mechanism and binding sites. Finally, this review provides a perspective on the host-guest chemistry of Al-MOFs.

One-step purification of ethylene is an important research topic in the petrochemical field, as it directly influences the energy consumption and economic efficiency of olefin production processes. In recent years, multicomponent metal- organic frameworks (MOFs), owing to their structural tunability and functional diversity, have demonstrated significant potential in C₂ hydrocarbon gas separation and purification of products from methanol-to-olefins (MTO) processes. To address the limitations of conventional single-metal-center MOFs, which often suffer from structural simplicity and restricted functionality, this work proposes a controllable construction strategy for multicomponent MOFs based on the assembly of metal- ligand units. Specifically, 2,2′-biquinoline-4,4′-dicarboxylic acid (H₂BQDC) was employed as the organic ligand and coordinated with CuBr via an in situ reaction to form the metal-ligand unit Cu(BQDC)₂. Subsequently, solvothermal reactions with ZrOCl₂, Fe₃O(OAc)₆(H₂O)₃, and Bi(NO₃)₃•9H₂O successfully yielded three structurally well-defined multicomponent MOF materials: Zr-Cu-BQDC, Quat-Fe-Cu-BQDC, and Quat-Bi-Cu-BQDC. Comprehensive structural characterization and gas adsorption measurements reveal that the introduction of different metal centers leads to significant variations in pore size, coordination environment, and surface chemical properties, which in turn result in distinct adsorption and separation behaviors. Among them, Zr-Cu-BQDC and Quat-Fe-Cu-BQDC exhibit preferential adsorption toward C₂H₂ and C₂H₆, enabling one-step separation of high-purity C₂H₄ from ternary C₂H₂/C₂H₆/C₂H₄ mixtures. In contrast, Quat-Bi-Cu-BQDC shows stronger affinity for C₃H₆ and demonstrates effective separation performance for C₃H₆/C₂H₄ mixtures typically found in MTO products. The feasibility of achieving efficient one-step ethylene purification under ambient conditions was validated through single-component gas adsorption measurements, ideal adsorbed solution theory (IAST) predictions, and dynamic breakthrough experiments. This work not only develops an efficient synthesis strategy for multicomponent MOFs based on metal-ligand units and enriches the preparation pathways of multicomponent MOFs, but also provides new insights and theoreti- cal guidance for the rational design of olefin separation materials tailored for practical industrial applications, highlighting both significant academic value and promising industrial potential.

The separation of carbon dioxide (CO₂) and acetylene (C₂H₂) using solid adsorbents represents a viable approach for producing C₂H₂ in industrial applications. To address the issues of ionic liquid (IL) leaching and limited stability in IL-incorporated metal-organic framework (MOF) composites, we developed a strategy involving the covalent crosslinking of the IL using a diepoxy crosslinker. The covalent cross-linked network not only effectively restricts the migration and leaching of ionic liquids on the MOF surface but also enhances the overall chemical and thermal stability of the composite material. Specifically, this strategy is based on the ring-opening polymerization reaction between the epoxy groups on the cross-linker (ethylene glycol diglycidyl ether, EGDE) and the amine groups on the ionic liquid ([TEPA][Py], where [TEPA] is tetraethylenepentamine and [Py] is pyrazole). This constructs a stable covalent network within the ionic liquid, which is then firmly anchored onto the surface of ZIF-8 to form a core-shell structured adsorption separation material for CO₂/C₂H₂ separation. Although the crosslinked composite exhibited a lower CO₂ uptake (63.75 cm³•g⁻¹) compared to its non-crosslinked counterpart (80.29 cm³•g⁻¹), it maintained considerable adsorption capacity alongside high CO₂/C₂H₂ selectivity (>10⁴). The thermal stability of the composites was evaluated by thermogravimetric analysis (TGA). The results show that the crosslinked ionic liquid composite retained a larger mass at a given temperature compared to the pristine composite, demonstrating its enhanced thermal stability. The cross-linked adsorbent exhibited exceptional retention of its adsorption capacity over five consecutive adsorption-desorption cycles, with a negligible capacity loss of less than 0.6%. This performance stands in striking contrast to the severe degradation observed for the non-crosslinked composite, which suffered a rapid capacity loss of over 17% under identical conditions, providing direct evidence for the successful suppression of IL leaching. Finally, dynamic breakthrough experiments conducted under mixed-gas conditions confirmed the exceptional CO₂/C₂H₂ separation performance and practical potential of the developed cross-linked IL@MOF composite.

Removal of CO₂ impurity from C₂H₂ by physical-adsorption separation is energy-saving but extremely challenging because the two gases have very similar molecular dimensions and physicochemical properties. CO₂-selective (inverse) separation is more efficient, yet suitable adsorbents are scarce. Moreover, the stability, cost, and practical efficiency of adsorbents for gas separation must be addressed. This work employs two low-cost, stable porous coordination frameworks—Zn₃[Fe³⁺(CN)₆]₂ (ZnHCF) and K₂Zn₃[Fe²⁺(CN)₆]₂ (KZnHCF)—to overcome these obstacles. Their cage-like pore structures possess appropriate window sizes, enabling selective adsorption of CO₂ over C₂H₂. In KZnHCF, the K⁺ ions residing in the cavities electrostatically orient incoming CO₂ or C₂H₂ molecules differently, markedly enhancing CO₂ uptake and selectivity and partially mitigating the usual trade-off between capacity and selectivity. The material exhibits a remarkable saturated CO₂ adsorption capacity of 111.5 cm³•g⁻¹ at 298 K, and high CO₂-selective performance for 1∶1 (V/V) CO₂/C₂H₂ mixture, with an ideal adsorption solution theory (IAST) selectivity of 23.4 at 298 K and 0.1 MPa. More importantly, dynamic breakthrough experiments demonstrate that KZnHCF maintains highly efficient CO₂/C₂H₂ separation over a broad temperature range. From 50/50 (V/V) CO₂/C₂H₂ mixture at 298 K, the process yields C₂H₂ of >99.9 % purity with a dynamic productivity of 1915 mmol•kg⁻¹ in a single step—only slightly below the newly reported record. At 323 K, the productivity (1450 mmol•kg⁻¹) remains higher than most reported values at 298 K. This outstanding separation performance, combined with excellent stability, recyclability, low-cost, and facile scalable synthesis, positions KZnHCF as a promising adsorbent for efficient CO₂/C₂H₂ separation in practical applications.

With the continuous development of agriculture and industry, nitrate (NO₃⁻) pollution in water bodies worldwide remains a serious issue, characterized by decentralized distribution across multiple sites. The electrocatalytic nitrate reduction reaction (eNO₃RR) technology enables the reduction of NO₃⁻ waste into ammonia (NH₃)—a substance useful to humans—under ambient temperature and pressure. However, under near-neutral pH conditions that mimic actual aquatic environments, eNO₃RR faces multiple bottlenecks, including limited proton supply, competition from hydrogen evolution side reactions, risks of nitrite (NO₂⁻) accumulation, and insufficient catalyst lifespan. Metal-organic framework (MOF) materials, which have attracted significant attention recently, hold tremendous potential. Their tunable porous structures and well-defined active sites are conducive to improving NO₃⁻ reduction efficiency and selectivity. Remarkable progress has been made in this field: advanced MOF-based materials have achieved an NH₃ Faraday efficiency (FE) of nearly 99%, suppressed NO₂⁻ accumulation, and pushed the NH₃ yield to >23000 μg•h⁻¹•mg_cat⁻¹. By constructing conductive composite structures and employing derivatization strategies, MOF-based materials can maintain a FE of >90% and remain stable for over 10 h at industrial-level current densities (>950 mA•cm^-2). This review focuses on MOF-based electrocatalysts and systematically analyzes the mechanism of neutral eNO₃RR. Leveraging the atomic-level designability of MOFs, strategies such as single-atom/cluster regulation, multi-metal synergy, conductive composites, and derivatization can precisely overcome the bottlenecks of proton supply, hydrogen evolution competition, and stability in neutral eNO₃RR, enabling efficient conversion of pollutants to NH₃. Nevertheless, several challenges remain before this goal is fully achieved: the dynamic identification of active centers during catalysis is not sufficiently clear and accurate, long-term stability in real water bodies needs verification, and issues such as large-scale synthesis urgently require solutions.

Renewable light-driven photocatalytic CO₂ reduction (CO₂RR) has emerged as a promising strategy to mitigate greenhouse gas emissions while producing value-added chemicals and fuels. However, the efficiency of solar-driven photocatalytic systems remains limited by rapid recombination of photogenerated charge carriers, which represents a critical bottleneck for technological progress. Herein, ultrasmall WO₃ nanoclusters were successfully immobilized within the microporous framework of PCN-250 via a molecular cavity confinement strategy. Unlike pristine PCN-250, which primarily relies on monocomponent Fe^3＋ active sites, the immobilization of WO₃ nanoclusters enables the construction of a Z-scheme heterojunction. This unique architecture not only promotes efficient charge separation but also preserves the strong redox potentials of both components, thereby significantly enhancing the photocatalytic CO₂ reduction performance. High-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) analysis confirms the effective confinement and encapsulation of WO₃ nanoclusters within the PCN-250, where WO₃ species self-assemble into ultrathin nanoclusters with diameters ranging from 0.8 to 1.4 nm. UV-Vis spectroscopy reveals that this nanoscale encapsulation markedly broadens the optical absorption, extending the absorption edge to 800 nm and thus spanning the entire visible light region. Using H₂O vapor as a proton source, the optimized WO₃@PCN-250-2 (W@P-2) composite exhibits a CO₂ photoreduction rate of 516.07 μmol•g^－1, which is 9.1 times higher than that of pristine WO₃. Mechanistic studies indicate a Z-scheme charge transfer pathway at the WO₃/PCN-250 interface. In-situ FTIR spectroscopy identifies *COOH as the key intermediate during CO₂ reduction to CO. This work offers a valuable reference for designing Z-scheme heterojunctions toward efficient CO₂ photoreduction.

Luminescent Cu(I)-halide(X) MOFs provide a useful testbed for relating small structural changes to band-edge electronic structure, but comparable halide series with fixed topology are still limited. Herein, three Cu(I)-halide MOFs, Tbpo-Cl, Tbpo-Br and Tbpo-I, were obtained solvothermally from a tripodal benzimidazole linker (Tbpo) and CuX (X=Cl, Br, I). Single-crystal X-ray diffraction shows that all three compounds adopt the same two-dimensional topology with similar coordination motifs. The Cu…Cu separations decrease from 0.317 nm (Tbpo-Cl) to 0.305 nm (Tbpo-Br) and 0.259 nm (Tbpo-I). Thermogravimetric analysis reveals a gradual reduction in thermal stability from Tbpo-Cl to Tbpo-I, consistent with the lengthening/softening of Cu—X bonds and weaker lattice reinforcement by intermolecular contacts. All three frameworks display solid-state photoluminescence under excitation at 340 nm, with emission maxima at 423 nm (Tbpo-Cl), 408 nm (Tbpo-Br) and 455 nm (Tbpo-I), demonstrating a non-monotonic halide dependence. Density functional theory calculations were used to clarify the origin of this behaviour. Density of states (DOS) analyses indicate a Cu—X hybridized valence-band edge, suggesting that the low-energy transition involves charge transfer between the inorganic unit and the ligand. The calculated band gaps follow the order Br>Cl>I, matching the emission-energy trend. In particular, the short Cu…Cu contact in Tbpo-I (0.259 nm) is compatible with stronger cuprophilic interactions and the stabilization of lower-energy Cu-centred states, accounting for the pronounced red shift. These results connect halide identity, metal-metal proximity and framework rigidity to the thermal and photophysical behaviour in a topology-fixed Cu(I)-halide MOFs.

Efficient separation of CH₄/N₂ mixtures is important for the upgrading and utilization of coalbed methane, because the high N₂ content in raw gas markedly lowers its calorific value and restricts its direct use as a fuel or chemical feedstock. Adsorptive separation under mild conditions is considered a promising alternative to energy-intensive cryogenic distillation; however, the development of adsorbents that combine competitive CH₄/N₂ separation performance with scalable, low-cost, and green synthesis remains challenging. Herein, we report a layered manganese-based coordination polymer, Mn-DHBQ, as a promising adsorbent for CH₄/N₂ separation. Mn-DHBQ was synthesized from manganese acetate tetrahydrate and 2,5-dihydroxy-p-benzoquinone in pure water at room temperature using inexpensive and commercially available precursors. Structurally, Mn-DHBQ is composed of one-dimensional coordination chains that are further stacked through intermolecular hydrogen bonding to form a quasi-three-dimensional supramolecular microporous network. Powder X-ray diffraction confirmed the phase purity and crystallinity of the as-synthesized material, while N₂ sorption at 77 K gave a BET surface area of 428.7 m²•g⁻¹. Gas adsorption measurements showed that Mn-DHBQ adsorbs CH₄ much more strongly than N₂. At 298 K and 0.1 MPa, the CH₄ uptake reaches 1.10 mmol•g⁻¹, whereas the N₂ uptake is only 0.27 mmol•g⁻¹. The corresponding IAST CH₄/N₂ (V/V, 50/50) selectivity is 5.82 at 298 K. Virial analysis further revealed a higher isosteric heat of adsorption for CH₄ (28.85 kJ•mol⁻¹) than for N₂ (10.59 kJ•mol⁻¹), indicating a substantially stronger affinity of the framework toward CH₄. Dynamic breakthrough experiments using an equimolar CH₄/N₂ mixture at 298 K and 0.1 MPa demonstrated clear separation behavior, with N₂ eluting rapidly and CH₄ breaking through at 10.2 min•g⁻¹; the dynamic CH₄ uptake reached 0.46 mmol•g⁻¹, close to the equilibrium uptake at the corresponding partial pressure. In a single adsorption-desorption cycle, the CH₄ concentration could be enriched to above 98.9%, and stable separation performance was maintained over three cycles. Importantly, Mn-DHBQ was further synthesized on a 1000-fold larger scale in water within 8 h, affording about 0.21 kg product with a space-time yield of 63 kg•m⁻³•d⁻¹. The scaled-up sample retained comparable crystallinity, porosity, morphology, and CH₄/N₂ breakthrough performance to the mg-scale material. These results indicate that Mn-DHBQ is a promising and practically relevant adsorbent for CH₄ enrichment and coalbed methane upgrading.

1-Hydroxypyrene (1-HP) is the final metabolite of polycyclic aromatic hydrocarbons (PAHs) in the human body and is an important biomarker for assessing human exposure to genotoxic PAHs. However, the existing analytical methods are difficult to achieve high selectivity, ultra-high sensitivity, and rapid response simultaneously, which limits their application in on-site rapid screening. To address this issue, this study successfully constructed a new metal-organic framework (MOF) material NKM-456-Eu based on europium ions and the rigid octahedral acid ligand (H₈HPA-2Me). This material fully utilizes the large π conjugated system and restricted rotation ability of the ligand to achieve a unique fluorescence response to the target substance. As a fluorescence quenching sensor, NKM-456-Eu performs excellently in high sensitivity and high selectivity detection of 1-HP in N,N-diethylformamide (DEF) solution and complex human urine matrix. It shows the characteristics of ultra-fast response (5 s), ultra-high quenching constant (K_sv=83,280 L/mol), and ultra-low detection limit (0.0061 μmol/L). Moreover, this sensor exhibits excellent interference resistance to common urine components such as urea, creatinine, and glucose, and shows good recovery and reliability in artificial urine matrix detection, demonstrating its practical application potential. Mechanism studies show that NKM-456-Eu has a tunable "antenna effect", generating dual emissions at 432 nm (attributed to the π→π* transition of the ligand center) and 616 nm (caused by charge transfer from the ligand to the metal). The fluorescence quenching arises from a synergistic interplay of multiple mechanisms: 1-HP binds to the MOF via π-π interactions, and its absorption band overlaps with the excitation spectrum of the MOF, leading to an inner filter effect (IFE), concurrent with photoinduced electron transfer (PET). This competitive interplay disrupts the ligand-to-Eu³⁺ energy transfer, resulting in substantial fluorescence quenching. This study not only provides a promising strategy for the development of MOF-based luminescent sensors but also highlights the potential of Eu-MOFs in customizing antenna effects, promoting the development of high-performance fluorescent materials and sensor devices in the environmental and biomedical fields.

Zirconium-based metal-organic frameworks (Zr-MOFs) have attracted significant attention due to their remarkable chemical stability and highly tunable topological architectures. Post-synthetic ligand insertion engineering offers an important functionalization strategy capable of achieving precise design and modulation of the structure and function of the resulting Zr-MOFs, at the molecular level. This review systematically summarizes recent advances of ligand insertion within Zr-MOFs, with a focus on two dominant approaches of ligand installation and ligand exchange. It outlines the evolution from early-stage pendant-group modifications to the recent development of sequential ligand installation, elucidating the mechanisms, applicable scopes, and performance enhancements of these methods in areas such as gas adsorption/separation and heterogeneous catalysis, etc. Special emphasis is placed on how sequential ligand installation enables precise and stepwise incorporation of functional linkers through pre-engineered structural vacancies, thereby allowing atomic-scale modulation of pore microenvironments and enabling function enhancement. Finally, future challenges and prospects in scalable synthesis, multifunctional integration, and practical applications are discussed, providing theoretical guidelines for the rational design of high-performance Zr-MOFs materials.

Addressing the pressing challenge of high energy consumption and solvent waste in the industrial-scale production of metal-organic frameworks (MOFs), we report a rapid, green, and scalable mechanochemical strategy for the mass preparation of the highly efficient CO₂ adsorbent, UTSA-16(Zn). Unlike conventional solvothermal methods, this protocol using zinc acetate and potassium citrate dramatically shortens the synthesis time from 48 h to just 6 h. This achieves a remarkable 48-fold enhancement in space-time yield while reducing solvent consumption by approximately 90%. Crucially, we identify that the in-situ accumulation of acidic byproducts during grinding inhibits framework assembly. Precise pH modulation using 0.2 equiv. of triethylamine (TEA) is essential to buffer the reaction environment, preventing defect formation and ensuring high product crystallinity. The resulting material is structurally isomorphous to its hydrothermally synthesized counterpart, possessing a consistent pore environment with a high BET surface area of 817 m²/g. In terms of performance, the mechanochemically derived UTSA-16(Zn) exhibits exceptional CO₂ uptake (3.68 mmol/g at 296 K and 0.1 MPa) and an ultra-high ideal adsorbed solution theory (IAST) selectivity of 388 for CO₂/N₂ mixtures, driven by a significant difference in isosteric heats of adsorption. Dynamic breakthrough experiments further validate a robust dynamic CO₂ capacity of 1.94 mmol/g and stable recyclability under simulated flue gas conditions. This work not only provides a practical manufacturing route for UTSA-16(Zn) but also underscores the pivotal role of pH regulation in the green synthesis of advanced porous materials.

The extremely abundant reservoir of uranium resources in seawater is regarded as an important strategic pathway for alleviating future uranium shortage and supporting the sustainable development of nuclear energy. However, the ultra-low concentration of uranium in seawater, the presence of complex coexisting ions, and severe biofouling pose significant challenges to achieving efficient and selective uranium extraction. Covalent organic frameworks (COFs), a class of crystalline porous materials featuring tunable structures, well-defined pore channels, high specific surface areas, and excellent chemical stability, have demonstrated unique advantages in uranium extraction from seawater (UES) in recent years. This review systematically summarizes the latest research progress on COFs-based materials for UES, with particular emphasis on their applications and underlying mechanisms in adsorption, photocatalysis, and synergistic uranium extraction driven by external fields such as light and electricity. Strategies including functional group modification, skeleton and defect engineering, composites & heterojunctions, morphology control, donor-acceptor (D-A) structures, reaction-pathway regulation, etc. are discussed to analyze key advances in enhancing uranium extraction capacity, selectivity, kinetic performance, and resistance to biofouling. Finally, the challenges faced by COF-based materials in terms of large-scale application, long-term stability, and cost control are discussed, and future design directions and development trends for high-performance materials for UES are proposed. This review provides a systematic reference and conceptual insights for the in-depth study and practical application of COF-based materials in the field of UES.

Photocatalytic hydrogen evolution has emerged as a promising strategy for generating clean fuel. Covalent organic framework (COFs), which possess designability, large specific surface area and adjustable energy band, have gradually gained favor among researchers in recent years. However, their hydrogen-evolution activity is often restricted by rapid carrier recombination and limited electron transfer pathways. Although various strategies such as heterojunction construction or skeletal functionalization have been explored, they often involve complex chemical modifications that may compromise the crystallinity. In contrast, the host-guest assembly strategy offers a mild route to modulate optoelectronic properties without destroying the intrinsic porous structure. Here we report a C₆₀@TpPa-(CH₃)₂-COF composite with a markedly reinforced internal electric field (IEF) to increase the hydrogen-evolution rate. C₆₀ was selected as the guest due to its high electron affinity and size compatibility with the COF pores, acting as an ideal electron acceptor. The TpPa-(CH₃)₂-COF was synthesized via Schiff-base polycondensation between 2,4,6-triformylphloroglucinol (Tp) and 2,5-dimethyl-p-phenylenediamine (Pa-(CH₃)₂) in a 1∶1.5 molar ratio, using mesitylene and benzyl alcohol as solvents, with anhydrous acetic acid as a catalyst. The reaction mixture underwent freeze-pump-thaw cycles under vacuum before being sealed and heated at 120 ℃ for 72 h. After cooling, the product was filtered, washed with anhydrous THF, soaked in dry acetone for solvent exchange, and vacuum-dried at 120 ℃ for 12 h to obtain TpPa-(CH₃)₂-COF. For C₆₀ encapsulation, 20 mg of the COF was added to a 5 mL saturated C₆₀ solution in o-dichlorobenzene and heated at 60 ℃ for 3 d. After cooling, the composite was filtered, washed with warm o-DCB to remove physiosorbed C₆₀, and further washed with ethanol. The final product, C₆₀@TpPa-(CH₃)₂-COF, was vacuum-dried at 60 ℃ for 12 h. Comprehensive characterization confirms both framework formation and successful loading of C₆₀. Powder X-ray diffraction and Raman spectroscopy verify retention of the ordered lattice together with signatures of the guest fullerene. The IEF in C₆₀@TpPa-(CH₃)₂-COF is 4.32-fold higher than that of the pristine COF, which promotes spatial charge separation and transport. Complementary calculations indicate that pore-confined C₆₀ induces an uneven charge distribution and increase the polarity, thereby amplifying the IEF. Consequently, under AM 1.5 irradiation and loading 1% (w) of Pt, the optimized material delivers a hydrogen-evolution rate of 61.58 mmol•g^－1•h^－1. This performance represents a 5.63-fold enhancement compared to the pristine COF, and the apparent quantum efficiency (AQE) reaches 4.04% at 450 nm. At the same time, the photocatalyst demonstrated excellent cyclic stability and there had no obvious changes occurred in the structure after 24 h cyclic testing. In short, this approach utilizes the host-guest electronic interactions to enhance the strength of internal electric fields, offering a general and efficient route to high-performance COF-based photocatalysts for solar hydrogen production.

The development of framework materials chemistry has provided a powerful platform for constructing porous crystalline systems with precisely controllable structures and integrated functions. Chiral metal-organic frameworks (CMOFs) have attracted considerable interest owing to their ability to immobilize and amplify molecular chirality within crystalline frameworks, offering unique opportunities for asymmetric catalysis. However, the rational organization of multiple catalytic sites within rigid chiral frameworks, as well as the direct involvement of framework structures in stabilizing reaction intermediates and regulating selectivity, remains a significant challenge. Herein, using natural D-camphoric acid as a chiral source, a novel bifunctional ligand was rationally designed and synthesized, enabling the construction of a chiral copper-based metal-organic framework (D-Cam-Cu) featuring a staircase-like three-dimensional architecture. Single-crystal X-ray diffraction analysis reveals that the framework is assembled from paddle-wheel-type dinuclear copper units connected in a layer-by-layer manner, with adjacent layers exhibiting an ordered spatial offset, thereby generating a non-uniform chiral microenvironment. On this basis, the CMOF was integrated with a chiral phosphoric acid to establish a heterogeneous cooperative catalytic system, which was successfully applied to the asymmetric N—H insertion reaction between β-naphthylamine and α-diazocarbonyl esters. Compared with single-catalyst systems, the cooperative system exhibits markedly enhanced reaction yields and enantioselectivities. Combined structural analysis and catalytic investigations suggest that the staircase-like chiral framework plays a crucial role in stabilizing key reaction intermediates, promoting cooperation among multiple active sites, and regulating reaction selectivity. This work not only demonstrates the controllable transformation of natural chiral molecules into functional chiral framework materials but also provides new design principles for developing multifunctional cooperative asymmetric catalytic systems based on framework materials.

Efficient capture and electrocatalytic conversion of low-concentration carbon dioxide (15% in flue gas and 720 mg/m³ in ambient air) represents a promising pathway toward carbon emission mitigation and value-added chemical production. In principle, directly utilizing dilute CO₂ streams could bypass energy-intensive purification steps and improve the overall process economics. However, electrocatalytic CO₂ reduction (eCO₂RR) under low CO₂ partial pressures is fundamentally limited by sluggish CO₂ mass transfer, severe competition from the hydrogen evolution reaction, and performance deterioration induced by impurities (e.g., O₂, NO_x, and SO₂). Moreover, conventional neutral/alkaline electrolytes suffer from pronounced carbonate formation, leading to substantial carbon losses and low single-pass carbon efficiency. These challenges indicate that simply improving intrinsic catalytic activity is insufficient; instead, new materials and system-level strategies are required to simultaneously enrich CO₂, regulate interfacial microenvironments, and decouple separation from conversion. Metal-organic frameworks (MOF), featuring tailorable pore architectures, designable pore chemistry, and the capability of integrating multiple functions into a single material or device component, provide a unique platform to address the above limitations. This Perspective highlights recent advances in MOF-based materials for eCO₂RR using low-concentration CO₂ feedstocks, with an emphasis on representative design paradigms spanning “molecular-scale synergy - reaction-environment regulation - device-level integration”. First, capture and conversion can be coupled within individual MOFs by embedding CO₂-philic motifs and catalytic centers into the same porous scaffold, enabling preferential CO₂ enrichment, and facilitated transport to active sites under simulated flue gas. Second, reaction-environment engineering, particularly under acidic conditions, offers a viable solution to suppress carbonate formation and enhance carbon utilization; protonation of N-rich frameworks can strengthen CO₂ adsorption/transport while limiting proton accessibility to catalytic sites, leading to high Faradaic efficiency and improved single-pass conversion even with dilute CO₂ inputs. Third, device-level strategies further decouple CO₂ purification from downstream electrolysis by integrating MOF-based molecular sieving mixed-matrix membranes (e.g., MOF/PIM-1 composites) into membrane electrode assemblies, allowing in situ enrichment of flue gas- or air-derived CO₂ and impurity removal prior to catalytic conversion. Collectively, these advances demonstrate how MOFs can enable progressive innovations from materials design to interfacial regulation and electrolyzer integration. Finally, key challenges and opportunities are discussed, including mechanistic understanding under complex impurity mixtures, long-term stability, scalable manufacturing of MOF-based layers and membranes, and compatibility with industrial capture and electrolysis infrastructures.

The development of highly efficient and stable photocatalysts for solar-driven hydrogen peroxide (H₂O₂) production represents a pivotal direction in green chemistry research. Herein, we report the successful synthesis of a novel silver-based metal-organic framework (MOF) photocatalyst, Ag-TEPT (where TEPT=2,4,6-tris(4-ethynylphenyl)- 1,3,5-triazine), which was constructed via a metal-carbon (M—C) bond coordination strategy to bridge Ag(I) clusters with triazine-based linkers. Under simulated sunlight irradiation, Ag-TEPT exhibited an outstanding H₂O₂ production rate of 2880 μmol•g⁻¹•h⁻¹ in a pure water-oxygen system without any sacrificial agents, a performance that significantly surpasses most reported photocatalysts. Impressively, it maintained a high production rate of 2024 μmol•g⁻¹•h⁻¹ even in ambient air. Furthermore, Ag-TEPT demonstrated remarkable photocatalytic stability with negligible activity loss over three consecutive reaction cycles. Post-catalytic characterization confirmed its unvaried crystal structure, morphology, and surface chemical states, attesting to its potential as a high-performance and durable photocatalyst. Mechanistic studies revealed a dual-pathway reaction mechanism, wherein H₂O₂ generation proceeds via simultaneous 2e⁻ oxygen reduction reaction (ORR) and 4e⁻ water oxidation reaction (WOR) processes. Notably, the O₂ produced from the 4e⁻ WOR serves as an internal feedstock for the 2e⁻ ORR, mitigating the dependency on exogenous O₂ and thereby enhancing the overall catalytic efficiency. In addition, the band structure of AgC-MOF, constructed from Tauc plot fitting and Mott-Schottky measurements, provided thermodynamic validation that Ag-TEPT is suitable for the photocatalytic reduction of O₂ to H₂O₂ and the oxidation of H₂O to O₂, but not for the direct oxidation of H₂O to H₂O₂. Photoluminescence spectroscopy and photoelectrochemical measurements confirmed the exceptional photogenerated charge separation efficiency of AgC-MOF, a benefit derived from the superior electron transport capability of the Ag-alkynyl bonds, which led to markedly improved photocatalytic reaction kinetics. In particular, Ag-TEPT showed a substantially higher photocurrent density, attributable to the excellent photosensitivity of the triazine units within the TEPT linker.

Covalent organic frameworks (COFs), with their structural tunability, high specific surface area, and excellent chemical stability, have attracted increasing attention in the field of proton conductors in recent years. This review systematically summarizes the research progress of COF-based proton conductors, covering proton transport mechanisms, material design strategies, experimental characterization, theoretical simulation methods, and application prospects. Criteria for distinguishing between the Grotthuss mechanism, which involves proton relaying through a hydrogen-bonding network, and the Vehicle mechanism, which entails diffusion of protonated species, have been clarified based on extensive experimental measurements of activation energies and theoretical simulations of proton transport pathways. In general, an activation energy below approximately 0.4 eV suggests dominance of the Grotthuss mechanism, whereas higher values typically indicate the predominance of the Vehicle mechanism. Proton-conducting materials are commonly categorized into intrinsic and extrinsic systems based on the source of protons. Intrinsic systems construct stable conduction pathways by covalent bonding to anchor sulfonic acid groups, phosphate groups, or nitrogen heterocycles. Extrinsic systems are optimized for proton transport by loading H₃PO₄, ionic liquids, or polymers using confinement effects. In terms of experimental characterization techniques, electrochemical impedance spectroscopy (EIS) was employed to measure macroscopic conductivity and activation energy. Simultaneously, solid-state nuclear magnetic resonance (ssNMR) was utilized to the local chemical environment of protons, X-ray photoelectron spectroscopy (XPS) for analyzing the charge distribution of functional groups, and infrared spectroscopy for monitoring chemical bond vibrations and transformations. Furthermore, the potential applications of quasi-elastic neutron scattering (QENS) and isotope tracing techniques in other materials were also briefly discussed. Theoretical simulation methods encompass density functional theory (DFT), for calculating electrostatic potential and, combined with transition state search methods, proton migration energy barriers, classical molecular dynamics (MD), for calculating radial distribution function (RDF) and coordination number, and ab initio molecular dynamics (AIMD), for dynamic tracking of proton migration pathways. These methods have collectively revealed the microscopic regulatory mechanism of proton transport through pore geometry, functional group arrangement, and synergistic effects of hydrogen bonding. Finally, this review analyzes the application prospects of COF proton conductors in electrochemical energy conversion devices. We propose that integrated efforts in the design, experimental characterization, and theoretical simulation of COFs are essential for achieving performance optimization and advancing towards practical application, thereby enhancing proton conduction efficiency and material stability. Future research should integrate high-resolution characterization and multi-scale simulation to gain a comprehensive understanding of the proton transport mechanisms in COF materials, thus accelerating the application of COF-based conductors in promising hydrogen energy technologies.

Ethylene (C₂H₄) serves as a core raw material in the modern chemical industry, where its efficient separation and purification are of paramount importance. Compared to traditional distillation technology, adsorption separation technology offers significant advantages, including reduced energy consumption, lower costs, and simpler operational procedures. Ethane (C₂H₆)-selective adsorbents can directly obtain high-purity C₂H₄ through a single-step adsorption, simplifying the separation process and reducing energy consumption. Developing efficient C₂H₄ separation and purification technologies is a major demand for energy conservation, consumption reduction and green development in the chemical industry. The key to this research lies in the design and preparation of high-performance C₂H₆-selective adsorbents. The advent of Metal-organic framework (MOF), characterized by their high designability and adjustability, has significantly advanced the research and development of C₂H₆-selective adsorbents. By strategically designing active sites and precisely controlling pore environments, a diverse range of C₂H₆-selective adsorbents have been continuously developed. However, when facing actual separation systems and complex industrial application scenarios, the performance of these materials still needs to be improved, and there is an urgent need for further systematic research on the structure-activity relationship of the C₂H₆ adsorption mechanism. This study provides a comprehensive review of the research progress in C₂H₆-selective adsorbents over the past 15 years, delving into their structural design methodologies, such as flexible gate-opening effects, metal site modifications, and surface potential regulation. It also elaborates in detail on the influence mechanisms of different methods on the adsorption selectivity and capacity. In addition, it emphasizes the key challenges that C₂H₆-adsorbents must overcome in the face of industrial applications, including cyclic stability, green large-scale synthesis, and the establishment of new separation processes. It is expected to lay a theoretical foundation for the precise construction and separation application of high-performance C₂H₆-adsorbents, and to promote the technological innovation and transformative development of the olefin separation industry.

With the intensification of environmental challenges and the ever-growing global energy demand, conventional materials are increasingly unable to satisfy the stringent requirements in energy and environmental fields. Metal-organic frameworks (MOFs), as a class of crystalline porous materials composed of metal nodes and organic ligands, have emerged as promising candidates due to their tunable pore structures, exceptionally high surface areas, and versatile functionalities. These features enable MOFs to play a significant role in applications such as adsorption and electrochemical energy storage. However, the poor intrinsic electrical conductivity and limited structural stability of pristine MOFs restrict their practical implementation. To address these limitations, MOF-based composites have been developed by integrating MOFs with a variety of guest materials including inorganic carbonaceous materials (e.g., graphene, carbon nanotubes), metal oxides, and conductive polymers. These composites not only retain the inherent advantages of MOFs but also enhance conductivity, mechanical robustness, and chemical stability through synergistic interactions. Importantly, the integration strategies often involve the construction of heterostructures, interface engineering, and the introduction of chemically bonded interfaces, thereby promoting efficient charge transfer and long-term cycling stability. Herein, a comprehensive summary of MOF composites and their emerging applications in electrochemical energy storage systems, such as supercapacitors, lithium-ion batteries, lithium-sulfur batteries and aqueous zinc ion batteries, as well as in environmental adsorption processes targeting heavy metals and CO₂ capture, is offered. The discussion also emphasizes dimensional design from zero-dimensional (0D) nanoparticles to three-dimensional (3D) frameworks, each exhibiting unique advantages in terms of electron transport, ion diffusion, and active site accessibility. The relationships of these composites are analyzed, highlighting how different combinations and morphologies (e.g., core-shell architectures, layered hybrids, and flexible films) influence their functional performance. MOF composites represent a promising frontier for the development of next-generation functional materials. Their tunable dimensionality, enhanced chemical properties and multifunctional adaptability open up new avenues for solving urgent global issues in energy sustainability and environmental remediation.

Oxygen sensing plays a vital role in a variety of fields, including environmental monitoring, healthcare, industrial processes, and safety management. Metal-organic frameworks (MOFs), owing to their robust oxygen adsorption capacity and tunable structure, are anticipated to be applied in oxygen sensing to enhance response performance. In this work, we synthesized four common Zr-MOFs (MOF-808, UiO-66, NU-1000, NH₂-UiO-66) using the solvothermal method and validated the interaction between the ligands and zirconium clusters by comparing their fluorescence emission and lifetime. Then, the fluorescence of these four MOFs were tested under vacuum, air, and oxygen atmospheres. The experiments demonstrate that oxygen is the main air component that effectively quenches the fluorescence of zirconium-based MOFs. Recirculation experiments and powder X-ray diffraction of MOFs before and after fluorescence quenching indicate that zirconium-based MOFs exhibit high photo-stability. Under vacuum and pure oxygen conditions, UiO-66 can quench 88% of its fluorescence, with response and recovery times as low as 13 s and 15 s, respectively. This rapid detection of O₂ over multiple cycles suggests that UiO-66 possesses a high level of sensitivity. In contrast, the fluorescence of chromium-based MOFs with the same ligands is hardly affected. This may be related to the electronic structure of tetravalent zirconium being able to match the electronic structure of paramagnetic oxygen, allowing the fluorescence process of the MOF to be quenched under the action of oxygen. To explore the advantages of zirconium-based MOFs in oxygen sensing, density functional theory calculations are adopted to determine the adsorption energy of oxygen with MIL-100(Cr) and MOF-808(Zr), which have the same ligands, confirming that one of the reasons for the special sensitivity of zirconium-based MOFs to oxygen is the shorter collision radius between Zr metal clusters and O₂ molecules. The reduction in fluorescence lifetime confirmed the interaction between oxygen and the MOF. These findings are expected to provide theoretical guidance for the development of sensitive oxygen sensors.

Two-dimensional polymers (2DPs) are a type of planar polymer materials that possess regular porous structures. They fulfill the demand for thin, high-performing, and stable materials in flexible devices, making them highly potential candidates for applications in the field of flexible electronics. As a special class of covalent two-dimensional polymer materials, two-dimensional covalent organic frameworks (COFs) refer to crystalline porous materials with a two-dimensional topology formed by connecting π-conjugated building units through covalent bonds. The unique electronic structure of COFs gives them better electrical properties compared to other two-dimensional polymers. Furthermore, their unique periodic porous structure, high specific surface area, and excellent stability make them highly suitable for various applications such as ion transport, optoelectronic materials, and catalysis. Among these, carbon-carbon bond-linked COFs are regarded as one of the most promising types of two-dimensional polymers due to their excellent stability and good crystallinity. In recent years, many carbon-carbon bonded COFs with different structures and excellent properties have emerged based on different design principles and synthesis strategies. In this review, we summarize and introduce four common synthesis methods for preparing C=C bonded COFs, namely solvent-thermal method, melt-polymerization method, interface polymerization method, and copper template method. Furthermore, we categorize C=C bonded COFs into four classes: [C₂+C₃], [C₂+C₂], [C₃+C₃], and [C₄+C₂], according to the topological structure of the building units. We focus on analyzing the relationship between the composite structure of these COFs and their stability, electrical properties, catalytic performance, and other properties. Additionally, we compile and summarize the research progress of C=C bonded COFs in terms of synthesis methods, structural innovation, performance improvement, and practical applications. This compilation will be beneficial for researchers in the subsequent studies of C=C bonded COFs to select building units based on target structure and performance application and conduct pre-design. Furthermore, this review also includes previously overlooked C—C bonded COFs, providing a more comprehensive reference. In summary, this review aims to provide guidance for researchers in related fields to better design and synthesize multifunctional crystalline porous materials, thereby promoting the further development and application of carbon-carbon bond-linked COFs in various fields.