Cationic covalent organic frameworks (COFs) hold great potential for ion conduction and catalysis, yet poor crystallinity from interlayer electrostatic repulsion severely limits their performance. Herein, we demonstrate that lattice-matched polyoxometalates (POMs) as multifunctional counterions can direct the crystallization of cationic COFs and introduce functional sites. In situ incorporation of Keggin-type POMs affords highly crystalline honeycomb frameworks (POM@vCOF-CR), whereas post-synthetic ion exchange yields amorphous materials. Further investigations reveal that POMs play multiple roles during the crystallization process: in-plane, they modulate monomer release to promote ordered growth; out-of-plane, they act as electrostatic anchoring centers to facilitate ordered stacking. Crucially, lattice-matching between the POM sublattice and the COF framework eliminates configurational degeneracy and dictates long-range ordering. This principle is further validated in a square-lattice pvCOF, where only the larger Preyssler-type POM can form a matched square sublattice that enables crystallization, whereas smaller Keggin-type POMs lead to orientational disorder and amorphous products. Benefiting from the ordered functional sites and transport pathways, the crystalline POM@vCOF-CR exhibits significantly enhanced electrocatalytic activity for ethylbenzene oxidation and improved lithium-ion conductivity compared to its amorphous counterpart. This work establishes a rational solution for constructing crystalline cationic COFs by using lattice-matched POMs, thereby enabling functional frameworks with enhanced performance.

Proton shuttles play a vital role in diverse chemical transformations; however, most known examples, such as water and small organic molecules, operate in homogeneous systems with colocated proton donor and acceptor sites. In contrast, recyclable proton shuttle catalysts with spatially separated donor and acceptor sites are highly desirable due to their enhanced flexibility in proton transfer but remain largely unexplored. Herein, we identify the polyoxoniobate K7HNb6O1913H2O (KNb6) as a special type of recyclable proton shuttle catalyst that enables rapid cleavage of lignin beta-O-4 ketone into value-added phenol (yield: 93%) and benzonitrile (yield: 73%) within 10 min, using NH2OHH2O as the N-source. Combined computational and experimental studies reveal that the unique surface of KNb6, featuring a proton-donating hydroxyl group (-OH) surrounded by multiple proton-accepting oxo ligands (O2-), facilitates a proton-shuttling mechanism that drives both C beta-O and C alpha-C beta bond cleavage of a ketoxime intermediate formed in situ. Moreover, KNb6 maintains a stable catalytic performance over multiple cycles and efficiently promotes the depolymerization of oxidized natural lignin. This work not only provides a robust and recyclable catalyst for biomass valorization but also offers insights into the design of recyclable proton transfer systems.

Melting production plays a pivotal role in the modern copper industry. However, applying this process to fabricate nanocarbon (e.g., graphene, carbon nanotubes)-reinforced copper matrix composites has remained a long-standing challenge for nearly 2 decades. In this study, a melting preparation strategy for Graphene-Cu (Gr/Cu) composites was developed by introducing tungsten-doped graphene (W-Gr) into molten Cu, effectively improving the wettability and density compatibility between graphene (Gr) and molten Cu. The contact angle between W-Gr and molten Cu decreases to 80.4 degrees, while the density of W-Gr increases to 9.5 g cm(-3). W-Gr sheets containing 13 at% and 18 at% tungsten (designated as 13W-Gr and 18W-Gr) disperse uniformly within the Cu matrix. Thermodynamic analysis indicates that W-Gr can spontaneously disperse in molten Cu when the surface area fraction of WC on W-Gr exceeds 45.8%. The ultimate tensile strength (UTS) of 13W-Gr/Cu reaches 152 MPa in the as-cast state and 449 MPa after cold rolling. The electrical conductivity of 13W-Gr/Cu reaches 100.4% international annealed copper standard (IACS) at 20 degrees C, and is 1.5% higher than that of pure Cu at 180 degrees C. This work overcomes the challenges of fabricating Gr/Cu composites via the melting process, provides a viable approach for their large-scale industrial production.

Hundreds of thousands of tons of epoxy-containing carbon fibre (CF) wastes are generated from the manufacture of CF reinforced epoxy composites to their end-of-use. Today, most recycling strategies of these CF wastes aim at recovering CFs to the ones as virgin as possible, while techniques for efficiently converting CF wastes to materials of higher value, i.e., upcycling of CF wastes, are underexplored. Here, we develop a solid-flames upcycling technique using Mg and CaCO3 powders as reactants to convert CF wastes into graphene-grafted CFs (GCFs) and graphene powders within a few seconds. In Mg/CaCO3 solid-flames, Mg accelerates disconnection of C-O bonds in epoxy resins, promoting interconnection of C-C bonds that lead to the graphene-CF grafting microstructures. This solid-flames upcycling technique, with its superior sustainability metrics and attractiveness in commercial applications including reinforced graphite composites and electromagnetic interference shielding, presents a viable strategy for long-term management of accumulating CF wastes.

Single-cluster catalysts (SCCs) provide atomically precise active sites and model systems for mechanistic studies, but achieving uniform dispersion of clusters on supports remains challenging. Herein, a cationic porphyrin-viologen covalent organic framework (PV) is employed to immobilize diverse polyoxometalate (POM) clusters within its ordered channels via electrostatic assembly, thereby establishing a modular platform for fabricating well-defined SCCs. As a representative example, the sandwich-type Cu4(PW9)2 cluster was uniformly immobilized on PV, yielding Cu4(PW9)2@PV with high loading and stability. This catalyst exhibits remarkable catalytic activity in the electrocatalytic reduction of furfural to furfuryl alcohol, achieving 96.4% selectivity. The compositional tunability of POMs, together with the generality of this strategy, facilitates systematic mechanistic investigations. Combined experimental and theoretical analyses (control experiments, kinetic isotope studies, electrochemical and spectral analyses, DFT calculations, etc.) reveal that Cu sites serve as the catalytic centers, while polyoxotungstate units act as electron-proton reservoirs, switching the reaction pathway from hydrogen atom transfer to proton-coupled electron transfer. This work not only establishes a modular platform for the rational design and synthesis of SCCs but also provides new insights into the catalytic process of biomass electroreduction.

During the processing, manufacturing, and applications of energetic materials, twin structures are readily formed and have a significant impact on the mechanical response and sensitivity of energetic materials. However, the underlying mechanism of growth twinning during crystallization remains elusive. In this work, a solvation-desolvation mediated twinning behavior of high explosive 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX) in γ-butyrolactonethe (GBL) has been characterized by powder X-ray diffraction (PXRD), optical microscopy (OM), and single-crystal X-ray diffraction (SCXRD), and the formation mechanism of HMX twins has also been discussed. A single crystal of mediated solvate HMX·GBL has grown in a droplet-confined crystallization method, and the crystal structure was determined by SCXRD. In-situ PXRD results successfully replicated the phase conversion in the bulk recrystallization, strongly suggesting a solvation-desolvation mediated mechanism for the formation of twinned HMX from the desolvation of HMX·GBL. Two solvent accessible channels, [100] and [010], were found in the solvate structure to form the pathways for the solvent molecules to release from the solvate structure, leading to a morphology of two-domain crystals interconnected by a twin boundary between them. Moreover, because of the mismatch between the domain crystals, microdefects were observed around the terminals of the twin boundary, and additional domain crystals may grow in this region, which is confirmed by the in-situ OM observation. This study provided a comprehensive understanding of the twin formation mechanism of HMX crystals in a GBL solution, which is valuable to the crystal growth and morphology control of HMX and other energetic crystals for their performance improvement.

Direct sintering graphene powders into macro-scale and high-performance graphene-based composites presents a significant challenge due to high melting point of graphene. Besides, the problem of high temperature oxidation and ablation of graphene restricts its application. Here, centimeter-scale graphene composites were fabricated from boron nanoparticles and self-propagating high-temperature synthesis (SHS) graphene by spark plasma sintering (SPS). The B-C bonds and Y-type carbon structures are composed of covalent bonds, exhibiting stronger interactions than the conventional interfacial interactions and benefiting to improve the mechanical properties of graphene-based composites. Thus, the boron-graphene composite presents an exceptional flexural strength (309 MPa), superior compressive strength (487 MPa) and remarkable microscale compressive strength (6.25 GPa). It also exhibits outstanding oxidation resistant (the weight loss was only 0.2 % after oxidized at 1000 degrees C). Furthermore, we employed molecular dynamics (MD) simulations to understand the strengthening mechanism conferred by boron linkage. The high-performance boron-graphene composites are lightweight, easy to prepare, and cost-effective, rendering them uniquely advantageous for practical applications across various fields.

Polymer-bonded explosives (PBXs) balance energy density and mechanical performance by integrating rigid high-energy crystals within soft polymer matrices. However, interfacial incompatibility from large modulus mismatch induces inefficient stress transfer, localized stress concentrations, and premature failure. Inspired by biological modulus gradients bridging soft/hard tissues, we engineer the octahydro-1,3,4,7-tetranitro-1,3,5,7tetrazocine (HMX) / F2314 interface via in situ construction of nanoscale surface structures dimensionmatched to the radius of gyration (Rg) of F2314 chains. These nanostructures act as molecular anchors, constraining polymer mobility to induce a crystalline/semi-crystalline interphase. This yields a sixfold-thicker interphase (509 +/- 42 nm vs. 67 +/- 25 nm), establishing a continuous mechanical gradient from rigid HMX to soft matrix. The gradient interphase shifts failure modes from interfacial debonding to cohesive matrix rupture and trans-granular fracture, confirming enhanced stress transfer. Mechanical/morphological analyses verify improved load-bearing without compromising energetic performance. Crucially, this modifier-free strategy enables scalable interfacial reinforcement for next-generation PBXs. Crack redirection through the graded interphase and optimized stress distribution significantly enhance damage resistance and interfacial stability.

The development of green, efficient, and economical catalysts for the transformation of biomass into value-added chemicals is vital for advancing sustainable chemical manufacturing. In this work, a series of cost-effective and stable zirconium-based catalysts were synthesized via coordination of Zr4+ with malic acid (MA), a low-cost and naturally abundant organic ligand, in aqueous solution. By precisely tuning the ligand-to-metal molar ratio, the porous structure properties of the resulting materials could be finely controlled. In addition, the Br & oslash;nsted-to-Lewis acid site ratio reached 0.37, indicating a well-balanced acidic environment. These structural and acidic characteristics collectively contributed to its superior catalytic performance in the conversion of ethyl levulinate (EL) to gamma-valerolactone (GVL) via transfer hydrogenation and intramolecular lactonization. Kinetic analysis revealed that elevated temperatures promote the direct transformation of EL to GVL; however, temperatures beyond the optimal range induce competing transesterification reactions, thereby extending the reaction pathway. Notably, the catalyst retained its activity over at least six consecutive cycles without detectable deactivation. A mechanistic framework is proposed to provide deeper insight into the transfer hydrogenation process mediated by this class of Zr-based coordination catalysts.

The sintering and densification of graphene/ceramic composites pose significant challenges owing to the high melting point of graphene and ceramic phases. Here we address these challenges by using boron, silicon, and graphene as raw materials to prepare graphene/ceramic composites via spark plasma sintering (SPS) at 1600 degrees C. Boron and silicon significantly reduce the sintering temperature and improve the relative density of the composites. The abundant Y-type carbon structures effectively inhibit the sliding between graphene layers, improving the shear strength of few-layer graphene. Additionally, the strong Si-C and B-C interfacial bonding synergistically reinforce the composites, leading to exceptional mechanical strength, with the flexural strength of 561 MPa, the compressive strength up to 2.17 GPa, and the microscale compressive strength reaching 11.3 GPa (700 nm in diameter). Meanwhile, the composite exhibits impressive fracture toughness of 7.5 MPa center dot m1/2. Molecular dynamics simulations indicate that Y-type carbon structures allow for plastic deformation. The graphene/ ceramic composites not only demonstrate superior strengths but are also easy to prepare, making them particularly advantageous for wear-resistant components, ballistic armor and aerospace materials.

The C-N bonded aromatic compounds have demonstrated potential applications in energetic materials, polymers, agrochemicals, and medicinal chemistry. Developing improved methodologies for the streamlined and economical generation of C-N bonds is highly sought-after. In this study, an efficient strategy was developed to construct C-N bonded bis-heterocyclic compounds. A total of 26 substrates with different functional groups substituted azoles were selected to react with 1,3,4-trinitropyrazole. The results demonstrate that the C-N coupling reaction is predominantly influenced by the pK a of the substrates. The relationships between the substrates and C-N coupling products were meticulously investigated and determined. Among those products, compounds 3a-3d exhibit high thermostability and comparable detonation properties to that of RDX, indicating significant potential for use as secondary explosives. The method presented in this work may also serve as a powerful toolkit to design and synthesize C-N bonded bis-heterocyclic compounds in the domains of medicinal chemistry and organic materials.

In the realm of advanced materials research, graphene/Cu composites have emerged as promising candidates due to their exceptional properties. This study explores the critical role of carbon source type in optimizing the performance of in-situ graphene/Cu composites. By systematically investigating 18-carbon chain olefins with different end-functional groups in octadecene (ODE), oleic acid (OA) and oleamine (OAM) as carbon sources, we uncover their profound impact on graphene quality, composite grain boundaries, and load transfer efficiency. OA and OAM can enhance carbon retention and promote the formation of Cu2O and Cu3N nanoparticles, thereby enhancing the binding of graphene/Cu interfaces and improving load transfer. Moreover, the functional groups in the carbon sources play a crucial role in copper grain refinement and strengthening, which enhances the overall mechanical properties. Specially, the composites prepared with OAM demonstrated superior mechanical properties, including the highest yield strength (468 MPa), tensile strength (515 MPa), and fracture elongation (11.9 %), as well as good electrical conductivity (87.8 % IACS) and a low resistance temperature coefficient (3.46 x 10-3 degrees C- 1). This study underscores the importance of carbon source selection in optimizing graphene/Cu composites and provides valuable insights into the intricate relationship between chemistry, microstructure, and material properties, paving the way for the rational design of multifunctional materials.

Drug delivery to the gastrointestinal (GI) tract is a significant challenge in biomedicine. With the increasing incidence of digestive diseases worldwide, there is a growing interest in accurately and efficiently delivering drugs for GI diseases. In particular, the adverse effects of the acidic environment in the GI tract, pepsin, and intestinal epithelial structure on oral administration pose difficulties in effective treatment. Therefore, novel approaches are needed to consider the above-mentioned topics. Metal-organic frameworks (MOFs) have shown outstanding application interests in drug delivery for gastrointestinal diseases due to their good loading capacity, excellent bio-compatibility, and suitable degradation ability. This article reviews the pathogenesis and treatment status of gastrointestinal diseases, summarizes the different preparation methods of MOFs, and focuses on the principle and application of drug delivery system from MOFs in the gastrointestinal tract (GIT) in anti-inflammatory, wound repair, and anti-cancer. In addition, the practical effects of these porous materials in treating gastrointestinal diseases are explained, too. Finally, the potential application prospects of MOFs are summarized as potential drug-delivery systems in gastrointestinal diseases.

A mild and efficient way to form fused N -> O moiety by in situ ring closure reaction was proposed and studied. Compared with other methods to synthesize fused N-oxides, the new strategy is much safer and easier. The obtained compound, 4-amino-7-nitro-[1,2,4]triazolo[5,1-d][1,2,3,5]tetrazine-2-N-oxide (NTTO), was isolated with good purity and fully characterized. NTTO has a high density of 1.841 g & sdot;cm-3 and a high decomposition temperature of 262 degrees C. Compared with the traditional high energy insensitive energetic compound FOX-7, NTTO shows a higher detonation velocity of 8907 m & sdot;s-1 and lower sensitivity (IS = 40 J, FS = 252 N), demonstrating a promising candidate as a high energy insensitive energetic material. Compared with the traditional ortho-Camino/C-nitro structure, the formed 4-amino-1,2,3,5-tetrazine-2-oxide ring shows greater promise in designing energetic materials with high energy and low sensitivity.

The oxidative depolymerization of beta-O-4 linkages into value-added aromatic chemicals is of great importance for lignin valorization. However, achieving highly selective and rapid cleavage of beta-O-4 linkages under mild conditions remains a challenge. Herein, cobalt-cobalt oxides (Co-CoOx) supported on N-doped carbon (CoMA/C900) combined with a green and recyclable base K7HNb6O19 (KNb6) have shown remarkable activity for the one-step oxidative cleavage of lignin beta-O-4 linkages. Under relatively mild conditions (100 degrees C, 0.2 MPa O2), a lignin beta-O-4 alcohol model compound was almost completely converted within 3 h, affording a narrow product distribution of phenol (yield: 99%) and methyl benzoate (yield: 98%). Based on the control experiments, kinetic study, and spectroscopic analysis, a synergistic oxidative cleavage mechanism was proposed: CoMA/C900 activates molecular oxygen to form a superoxide radical, while basic KNb6 promotes deprotonation of secondary alcohol, and they synergistically catalyze the oxidation of beta-O-4 alcohol and the rapid cleavage of C beta-O and C alpha-C beta bonds. During the reaction, the oxidation of beta-O-4 alcohol to beta-O-4 ketone is the rate-determining step, while the cleavage of PP-one to phenol and methyl benzoate can be completed within 15 min. Moreover, the CoMA/C900-KNb6 catalyst is recyclable at least three times and highly active for the oxidative cleavages of other lignin models and organosolv birch lignin.

In the pursuit of advanced materials with multifunctional capabilities, graphene-based composites have gained substantial attention due to their exceptional mechanical, electrical properties, etc. In this paper, we present a straightforward method for fabricating graphene/Cu composites with an oriented bimodal structure through an in-situ synthesis process combined with hot rolling. Dendritic copper powder, mechanical exfoliation graphene and polyacrylonitrile were used as the raw materials. The graphene/Cu composite with oriented bimodal grains achieves a good balance between strength, ductility and electrical conductivity. Both the fine grains arising from the raised fine particles of dendritic copper powder and the graphene coated on the surface of fine grains facilitate the load transfer, resulting in improved strength of the composites. Furthermore, the formation of coarse grains during sintering and hot rolling deformation contributes to enhanced ductility. Simultaneously, the oriented structure of these coarse grains and graphene sheets establishes an efficient charge transport pathway, ensuring high electrical conductivity. The tensile yield strength of the oriented bimodal composite measures 315 MPa with 0.073 wt% carbon content, while its fracture elongation is 12.4%, and the electrical conductivity remains at 95.7% IACS. This study not only sheds light on the synergistic effects between graphene and copper in a bimodal composite system but also introduces a methodology for tailoring the microstructure to achieve a desired balance between mechanical strength, ductility, and electrical conductivity.

The quest for the materials that boast efficient electromagnetic interference (EMI) shielding, strong strength and superb thermal dimensional stability is a burgeoning research area, particularly due to their critical applications in safeguarding sensitive circuits against microwave radiation, especially in the space environments. Graphene-based composites, leveraging the remarkable attributes of individual graphene nanosheets, emerge as prime contenders for fulfilling these sophisticated application requirements. In this study, we prepared boron-graphene composites via spark sintering, combining graphene sheets and boron nanoparticles. This method not only ensures high-performance outcomes but also remains cost-effective and suitable for large-scale production. Boron serves as a binder, facilitating the connection between adjacent graphene sheets and enhancing the graphitization process. The resulting composites demonstrated exceptional electrical conductivity (4.53 × 105 S·m-1) and superior EMI shielding effectiveness (average SET 83 dB, with the thickness of 0.25 mm), markedly surpassing previous graphene-based materials in terms of compressive strength (171.3 MPa), and exhibiting low thermal expansion and an ultra-low friction coefficient (0.04). Additionally, to unravel the evolution of boron in the graphene composite and the impact of boron on electrical conductivity, first principles calculations and density functional theory (DFT) were utilized. This investigation underscores the significant promise of boron-graphene composites as high-performance, multifunctional materials across various domains.

Graphene has attracted much interest in many scientific fields because of its high specific surface area, Young’s modulus, fracture strength, carrier mobility and thermal conductivity. In particular, the graphene oxide (GO) prepared by chemical exfoliation of graphite has achieved low-cost and large-scale production and is one of the most promising for Cu matrix composites. Here, we prepared a high strength, high electrical conductivity and high thermal conductivity reduced graphene oxide (RGO)/Cu composite by directly heating the GO/copper formate. The oxygen-containing functional groups and defects of RGO are significantly reduced compared with those of GO. The tensile yield strength and thermal conductivity of RGO/Cu composite with RGO volume fraction of 0.49 vol.% are as high as 553 MPa and 364 W/(m·K) at room temperature, respectively. The theoretical value of the tensile yield strength of the composite is calculated according to the strengthening mechanism, and the result shows that it agrees with the experimental value. After hot-rolling treatment, the ductility and conductivity of the composite materials have been greatly improved, and the ductility of the RGO/Cu composite with RGO volume fraction of 0.49 vol.% has been increased to four times the original. This work provides a highly efficient way to fabricate a high-performance RGO-reinforced Cu composite for commercial application.

The strategic design and assembly of bulk graphene materials represent a pivotal advancement for harnessing the inherent properties of graphene in practical applications. However, fabricating high-strength graphene-based bulk materials from graphene powders presents a significant challenge, primarily due to interlayer slippage between the graphene layers. Here, a unique Y-type connection structure was found in few-layer graphene synthesized by self-propagating high-temperature synthesis (SHS) and subsequently retained in graphene-based bulk materials prepared by spark plasma sintering (SPS) process. The Y-type connection structure and defectinduced linkages serve to cross-link the graphene-based bulk materials. Consequently, the bulk material exhibited an ultra-high compressive strength, reaching 2.14 GPa, supported by Molecular dynamics (MD) simulations which demonstrated that the Y-type connection structure increases the shear modulus and the load transfer rate. The Y-type connection structure plays a vital role in reinforcing the strength of graphene-based bulk materials, offering valuable insights for the microstructural design and property augmentation of other graphenederived materials. Besides it's ultra-high compressive strength, the graphene-based bulk material also performs a low thermal expansion coefficient (0.5 x 10(-6) K-1), high electrical conductivity (1.47 x 10(5) S-1) and exceptional EMI shielding capability.