Hollow Metal-organic Framework Research Articles

Portable and highly enhanced surface enhanced Raman scattering and photocatalytic activity of cost-effective hierarchical hollow metal organic frameworks heterostructures induced by etched titanium sheet

In order to effectively detect and remove organic toxics in wastewater, the facile construction of plug and play bifunctional materials is very vital. Herein, a kind of metal-organic frameworks (MIL-53 (Fe) with hollow tubular structure was induced by an etched Ti sheet (ET), and then small sized Ag nanoparticles (Ag NPs) were in-situ anchored evenly on the internal and external surfaces of MIL-53 (Fe). Subsequently, a new type of bifunctional material (ETMA) was assembled. Surface enhanced Raman scattering (SERS) and photocatalytic activity of the material were investigated with crystal violet (CV, a carcinogenic and teratogenic toxic) as an analyte. The results found that trace amount of CV (1 × 10−12 M) can still be sensitively detected by the fabricated ETMA, and analysis enhancement factors as high as 6.9 × 105 even though only 1.39 wt % Ag was contained in the ETMA. Moreover, nearly 100 % of CV can be rapidly degraded by the ETMA after irradiated for 15 min, which was 44.47 times and 7.27 times faster than those of ET-Ag (ETA) and ET-MIL-53 (Fe) (ETM), respectively. Additionally, the removal efficiency of total organic carbon (TOC) was as high as 75.44 %. The remarkable enrichment effect, the strong interaction among components, and the synergistic effect in the target ETMA material were responsible to the dramatically enhanced SERS and photocatalytic performances. In addition, the cost-effective ETMA exhibited excellent uniformity, repeatability, stability, and recyclability towards the detection and removal of CV in actual water samples, showing great potentials in monitoring and removing organic pollutants in practical ecological environment.

Selectively etched inhomogeneous metal-organic framework-derived CoS/N-codoped hierarchical hollow carbon for long-cycling lithium sulfur batteries

Owing to high theoretical energy density and potentially low cost, lithium sulfur (Li–S) batteries have become a viable alternative for use in future energy storage devices. However, practical applications of this battery type are limited by the significant volume change of S and the undesired shuttle effect of polysulfides during cycling, ultimately causing rapid capacity decay. Herein, we developed a novel method to fabricate a N-doped hollow carbon composite (CoS/HNC) embedded with well-dispersed CoS nanoparticles (NPs) through inheritable carbonization of functionalized hollow metal-organic frameworks (MOFs). Specifically, the hollow UiO-66-NH2 is created by a sequence involving (1) use of non-uniform nucleation-growth approach to generate inhomogeneous UiO-66-NH2 that has more defects in the core, and (2) selective etching of the less stable core to obtain hollow structure. The CoS/HNC composite has advantages associated with not only hollow nanostructure that buffers the volume expansion of S species during cycling, but also CoS that prevents the shuttle effect. More importantly, both experimental and calculated results reveal that CoS/HNC could catalyze the reduction of LiPSs more effectively and CoS/HNC heterostructure enables the short-chain polysulfide that obtained from the catalytic conversion of soluble long-chain polysulfide by CoS NPs to be deposited on HNC. This process avoids passivation of the catalytic site and ensures continuity of the catalytic conversion. Benefiting from integration of its intriguing composition and morphology advantages, an as-prepared CoS/HNC–S cathode exhibits significantly improved electrochemical performance and cycling stability associated with a low capacity decay of 0.05% per cycle over 800 cycles at 1 C.

Flexible Self-Supporting MOF-Based Bean Pod Cube Hollow Nanofibers for Ultralong Cycling and High Rate Na Storage.

Sodium-ion batteries (SIBs) have garnered significant attention due to their potential as an emerging energy storage solution. Tin sulfide (SnS) has emerged as a promising anode material for SIBs due to its impressive theoretical specific capacity of 1022 mA h g-1 and excellent electrical conductivity. However, its practical application has been hindered by issues such as large volume expansion, which adversely affects cycling stability and rate performance during the charge/discharge processes. In this study, a novel approach to address these issues by synthesizing the bean pod cube hollow metal-organic framework (MOF)-SnSx/NC@N-doped carbon nanofibers through a process involving electrospinning, PDA coating, and calcination. The Sn-MOF serves as a self-sacrificing template, facilitating the simultaneous dissociation of MOF and polymerization of dopamine, leading to the creation of hollow intermediates that retain tin components. Subsequent sulfidation results in the integration of the hollow MOF-SnSx/NC nanoparticles within 3D nitrogen-doped carbon nanofibers, forming the distinctive bean pod cube composite structure. This unique configuration effectively shortens the diffusion path and mitigates volume expansion for sodium ions, ultimately yielding an exceptional high rate performance of 130 mA h g-1 (10 A g-1) and an ultralong cycling performance of 328 mA h g-1 even after 3500 cycles (2 A g-1) as the anode for SIBs.

Metal-organic-frameworks derived hollow carbon derivatives: Controllable configurations and optimized microwave absorption

Metal-organic-frameworks (MOFs) derivatives with diverse architectures and adjusted chemical compositions have been recognized as one of the promising candidates in the field of microwave absorption, especially carbon derivatives with hollow structure. Herein, the recent strategies in fabrication of hollow MOFs derivatives and the relationship between hollow structure and microwave absorption performance are briefly summarized. Then, the synthesized mechanism and crucial factors in the formation of hollow structure are systematically analyzed. Finally, the current challenges and future research trends are predicted, which provide guidelines for the regulation of hollow MOFs derivatives and the manipulation of microwave absorption performance.

Hollow metal-organic framework-based, stimulator of interferon genes pathway-activating nanovaccines for tumor immunotherapy.

Nanovaccines have emerged as promising agents for cancer therapy because of their ability to induce specific immune responses without off-target effects. However, inadequate cytotoxic T lymphocyte response and low antigen/adjuvant encapsulation remain major obstacles to vaccinating against cancer. Herein, we designed a stimulator of interferon genes (STING) pathway-activating nanovaccine based on hollow metal-organic frameworks (MOFs) for tumor treatment. The nanovaccine (OVA@HZIF-Mn) was constructed by encapsulating a model antigen ovalbumin (OVA) into zeolitic imidazolate framework-8, followed by etching with tannic acid and functionalizing with manganese ions. Studies have shown that the nanovaccine can effectively enhance antigen uptake, STING pathway activation and dendritic cell maturation, triggering a robust immune response to inhibit tumor growth. In addition, no infection or pathological signs were observed in mice organs after multiple administrations. This study combines a simple assembly approach and superior therapeutic effect, providing a promising strategy for engineering effective nanovaccines.

Interconnected hollow metal–organic framework network towards excellent proton transfer for proton exchange membrane

Interconnected hollow metal–organic framework (MOF) network (GO@HZIF-8) was designed as an efficient proton transfer accelerator in Nafion membrane. GO@HZIF-8 was constructed by in situ synthesis of ZIF-8 onto graphene oxide (GO) and succedent etching with tannic acid (TA). The hollow construction and surface TA functionalization of hollow ZIF-8 (HZIF-8) bestowed composite membrane with superior water retention. This was highly beneficial to the rapid proton transfer. Besides, the hollow construction could effectively reduce the proton transfer resistance onto GO@HZIF-8. More importantly, the interconnective architecture between HZIF-8 by the tethering function of GO and the interfacial hydrogen bond interaction between GO@HZIF-8 and Nafion resulted in connective proton transfer routes at GO@HZIF-8 surfaces and GO@HZIF-8/Nafion interfaces. These dramatically accelerated the proton transfer of GO@HZIF-8/Nafion composite membrane, enabling a considerable proton conductivity (PC) of 0.301 S cm−1 under 90 °C, 95 % RH, ∼1.33-fold greater than that of the pure Nafion membrane (RN). Moreover, the composite membrane exhibited a peak power density of 45.8 mW cm−2, ∼1.22-fold higher than that of RN. These results menifest that constructing hollow MOF network possesses grand prospect in the construction of high performance proton exchange membranes (PEMs).

Highly active CoP embedded in hollow nitrogen-doped carbon as an efficient bifunctional electrocatalyst for rechargeable zinc-air batteries

Aqueous zinc-air batteries provide a possibility to replace fossil fuels. However, developing bi-functional electrocatalysts with high activity, low-cost and environmental friendliness for zinc-air batteries remains a challenge. In this work, we report an efficient bifunctional electrocatalyst (H–CoP@NC) that is fabricated by phosphating a hollow metal organic framework (MOF) prepared using a self-template method. The H–CoP@NC exhibits a half-wave potential of 0.81V (vs. RHE) for the oxygen reduction reaction (ORR), and an overpotential of 390 mV for the oxygen evolution reaction (OER) at a current density of 10 mA cm−2. Remarkably, the H–CoP@NC assembled zinc-air battery possesses a voltage gap of 0.82 V at a current density of 50 mA cm−2, and the voltage gap increases by only 0.01 V after 730 continuous charge and discharge cycles. This excellent electrocatalytic activity for ORR and OER can be attributed to the hollow structure, which improves mass transport during the electrocatalytic reaction, and the synergistic effect between CoP and heteroatom doped carbon skeletons which provide a high density of exposed active sites.

Preparation of novel hollow metal organic framework for enhancing flame retardancy of paraffin/EP thermal energy storage materials

AbstractParaffin is a potential thermal energy storage material, but leakage and flammability are the two major problems affecting its storage and safe use. Here, a novel flame retarded paraffin/epoxy resin composite was developed by using paraffin, epoxy resin and hollow metal organic framework (W‐UiO66‐PPA) as thermal energy storage material, supporting material and flame retardant, respectively. The thermal energy storage and flame retardancy performances were examined with differential scanning calorimetry, vertical burning, limiting oxygen index and cone calorimeter tests. The results show that the paraffin/epoxy resin retains intact without leakage when the content of paraffin reaches 40 wt%, and this material exhibits high melting latent heat and remarkable thermal recycling property. In addition, the flame retarded paraffin/epoxy resin shows excellent flame retardancy, which is attributed to the following three aspects: (1) the hollow structure with open vertices of W‐UiO66 is capable of absorbing and collecting the combustible gasses produced by the combustion of epoxy resin; (2) the Zr and W elements of W‐UiO66 can facilitate catalytic charring and form a dense char layer; (3) phosphorous‐containing free radicals are able to capture OH· and O· free radicals during the combustion of paraffin and epoxy resin, thus interrupting the combustion chain reaction. On the whole, the flame retarded paraffin/EP possesses excellent thermal energy storage, thermal recycling, and flame retardancy properties. Our work provides a fantastic inspiration for the rational design of other flame retarded form‐stable phase change materials.

Integration of Noble Metal Nanocrystals in a Hollow Metal–Organic Framework Shell

Integration of Noble Metal Nanocrystals in a Hollow Metal–Organic Framework Shell

Enhanced Electrochemical Sensing of Butylated Hydroxy Anisole through Hollow Metal–Organic Frameworks with Gold Nanoparticles and Enzymes

Enhanced Electrochemical Sensing of Butylated Hydroxy Anisole through Hollow Metal–Organic Frameworks with Gold Nanoparticles and Enzymes

Preparation of One-Dimensional Hollow Metal-Organic Frameworks via the Marangoni Effect.

The fabrication of one-dimensional hollow metal-organic frameworks (1D HMOFs) has attracted considerable attention for the catalysis and separation because of their large surface areas and short and continuous axial diffusion pathways. However, the fabrication of 1D HMOFs requires the use of a sacrificial template and multiple steps, limiting their potential applications. This study proposes a novel Marangoni-assisted method to synthesize 1D HMOFs. Using this method, the MOF crystals can undergo heterogeneous nucleation and growth, affording a morphology self-regulation process under kinetic control and forming tubular 1D HMOFs in one step without requiring additional treatment. This method is expected to open new avenues for synthesizing 1D HMOFs.

Dynamically modulated synthesis of hollow metal-organic frameworks for selective hydrogenation reactions

Dynamically modulated synthesis of hollow metal-organic frameworks for selective hydrogenation reactions

Preserving Macroporosity in Type III Porous Liquids

AbstractPreserving large permanent pore structures in a fluid may endow conventional liquids with emergent physical properties. However, such materials are challenging to make because of the tendency of the pores to be filled and occupied by the solvent molecules. Here, we report the design and synthesis of the first Type III porous liquid (PL) containing uniform yet stable 480 nm cavities. This was achieved by first constructing a single crystalline hollow metal–organic framework (MOF), UiO‐66‐NH2, through chemical etching. The thin yet defect‐free MOF shell effectively excludes the bulky poly(dimethylsiloxane) solvent molecules from entering the cavity through its 4 Å aperture, resulting in the preservation of both micro‐ and macroporosity in the PL. These enormous void spaces allow the PL to reversibly host and release up to 27 wt % water for up to 10 cycles. The switching between the “dry” state and the “wet” state led to a large changes of the thermal conductivity of the PL from 0.140 to 0.256 W m−1 K−1, affording a guest‐responsive liquid thermal switch with a switching ratio of 1.8.

Preserving Macroporosity in Type III Porous Liquids.

Preserving large permanent pore structures in a fluid may endow conventional liquids with emergent physical properties. However, such materials are challenging to make because of the tendency of the pores to be filled and occupied by the solvent molecules. Here, we report the design and synthesis of the first Type III porous liquid (PL) containing uniform yet stable 480 nm cavities. This was achieved by first constructing a single crystalline hollow metal-organic framework (MOF), UiO-66-NH2 , through chemical etching. The thin yet defect-free MOF shell effectively excludes the bulky poly(dimethylsiloxane) solvent molecules from entering the cavity through its 4 Å aperture, resulting in the preservation of both micro- and macroporosity in the PL. These enormous void spaces allow the PL to reversibly host and release up to 27 wt % water for up to 10 cycles. The switching between the "dry" state and the "wet" state led to a large changes of the thermal conductivity of the PL from 0.140 to 0.256 W m-1 K-1 , affording a guest-responsive liquid thermal switch with a switching ratio of 1.8.

Boosting membrane carbon capture via multifaceted polyphenol-mediated soldering

Advances in membrane technologies are significant for mitigating global climate change because of their low cost and easy operation. Although mixed-matrix membranes (MMMs) obtained via the combination of metal-organic frameworks (MOFs) and a polymer matrix are promising for energy-efficient gas separation, the achievement of a desirable match between polymers and MOFs for the development of advanced MMMs is challenging, especially when emerging highly permeable materials such as polymers of intrinsic microporosity (PIMs) are deployed. Here, we report a molecular soldering strategy featuring multifunctional polyphenols in tailored polymer chains, well-designed hollow MOF structures, and defect-free interfaces. The exceptional adhesion nature of polyphenols results in dense packing and visible stiffness of PIM-1 chains with strengthened selectivity. The architecture of the hollow MOFs leads to free mass transfer and substantially improves permeability. These structural advantages act synergistically to break the permeability-selectivity trade-off limit in MMMs and surpass the conventional upper bound. This polyphenol molecular soldering method has been validated for various polymers, providing a universal pathway to prepare advanced MMMs with desirable performance for diverse applications beyond carbon capture.

Selective coding dielectric genes based on proton tailoring to improve microwave absorption of MOFs

Regulating dielectric genes of hollow metal-organic frameworks is a milestone project for microwave absorption (MA). However, there is still a bottleneck in deciphering the contribution of various dielectric genes, making it hard to expand the MA potential from selective encoding gene sequences. Herein, a custom-made proton tailoring strategy is used to build a controllable cavity, and meticulously designed thermodynamic regulation promotes the rearrangement of carbon atoms from disorder to order, thus enhancing the characteristics of charge transfer. Meanwhile, the defect-configuration transformation from heteroatom to vacancy and geometric configuration of hollow structure increase the polarization-related dielectric genes. Therefore, MA performance is enhanced towards broadband absorption (6.6 ​GHz, 1.78 ​mm) and high-efficiency loss (−62.5 ​dB), making samples suitable for complex open electromagnetic environments. This work realizes the tradeoff between dielectric gene sequences and provides a profound insight into the functions and sources of various microwave loss mechanisms.

Beyond Pristine Metal-Organic Frameworks: Preparation of Hollow MOFs and Their Composites for Catalysis, Sensing, and Adsorption Removal Applications.

Metal-organic frameworks (MOFs) have been broadly applied to numerous domains with a substantial surface area, tunable pore size, and multiple unsaturated metal sites. Recently, hollow MOFs have greatly attracted the scientific community due to their internal cavities and gradient pore structures. Hollow MOFs have a higher tunability, faster mass-transfer rates, and more accessible active sites when compared to traditional, solid MOFs. Hollow MOFs are also considered to be candidates for some functional material carriers. For example, composite materials such as hollow MOFs and metal nanoparticles, metal oxides, and enzymes have been prepared. These composite materials integrate the characteristics of hollow MOFs with functional materials and are broadly used in many aspects. This review describes the preparation strategies of hollow MOFs and their composites as well as their applications in organic catalysis, electrochemical sensing, and adsorption separation. Finally, we hope that this review provides meaningful knowledge about hollow-MOF composites and their derivatives and offers many valuable references to develop hollow-MOF-based applied materials.

Dual-lanthanide hollow luminescence metal-organic frameworks and their sensing performance for trace water and nitrobenzene

Dual-lanthanide hollow metal-organic frameworks, Tb1-x/Eux-MOFs (x = 0, 0.02, 0.04, 0.06, 1) were successfully synthesized by a one-pot solvothermal method. The tunable luminescence color of green-yellow-orange-red can be achieved by variation of the Tb3+/Eu3+ ratio. The energy transfer between Tb3+ and Eu3+ is confirmed by monitoring the excited states lifetime of 5D4 (Tb3+) and 5D0 (Eu3+), and can be regulated by water content, which indicates that organic ligand, 1,3,5-benzenetricarboxylic acid (H3BTC) has good antenna effect. Also, Tb0.98/Eu0.02-MOFs are used to be luminescence sensors for the detection of trace water and nitrobenzene (NB). By simultaneous monitoring of the emission intensity at 545 nm and 617 nm, the detection limits (LODs) for water are 0.0068% and 0.0081%, respectively. Those for NB are 0.0962 ppm and 0.0668 ppm, respectively. The sensing mechanisms (energy transfer for water and electron transfer for NB) are determined.

A Novel Instantaneous Self-Assembled Hollow MOF-Derived Nanodrug for Microwave Thermo-Chemotherapy in Triple-Negative Breast Cancer.

Hollow materials derived from metal-organic frameworks (MOFs) have emerged in the biomedical field due to their unique properties, and different synthesis methods have been proposed. However, so far, the large-scale use of hollow MOFs is mostly limited by the timeliness of synthesis methods. Herein, we propose a new ultrasonic aerosol flow strategy for the instantaneous synthesis of a Zr-MOF-derived hollow sphere complex (ZC-HSC) in only one step. Through rapid transient heating, the coordination between metal salts and organic ligands occurs along with prompt evaporation of the solvent. The whole process lasts for only about 21 s, compared with several steps that take hours or even days for conventional synthesis methods. Based on the ZC-HSC, we designed a nanodrug with the functions of manipulating the tumor microenvironment, which can reshape the tumor microenvironment by improving tumor hypoxia and inflammatory microenvironment and promoting antiangiogenic therapy. Combined with microwave thermo-chemotherapy, the nanodrugs effectively treat triple-negative breast cancer (the tumor cell survival rate was only 34.76 and 31.05% in normoxic and hypoxic states, respectively, and the tumor inhibition rate reached 87.9% at the animal level), providing a new theoretical basis for the treatment of triple-negative breast cancer. This rapid, one-step, and continuous ultrasonic aerosol flow strategy has bright prospects in the synthesis of MOF-derived hollow materials and promotes the further development of large-scale applications of biological nanomaterials.

Ultrafine Ru nanoparticles in shape control hollow octahedron MOF derived cobalt oxide@carbon as high-efficiency catalysts for hydrolysis of ammonia borane

BackgroundEvolving cost-effective and high-efficiency catalysts for efficient ammonia borane (AB) hydrolysis is highly desired but leftovers are a great challenge. Catalysis with high efficiency may be achieved by rationally modifying the intention and electronic state. MethodsThe development of carbonized zeolite imidazole framework (ZIF-67) based Ru nanoparticles (NPs) dispersed Ru@Co3O4/NC-350 NPs catalyst composition was prepared for the carrier catalysts. The ZIF-67 was introduced with different calcination temperatures for the carbonized porous materials. Only the calcination temperature at 350 °C with Ru@Co3O4/NC-350 NPs shows the good ability in its catalytic activity. The addition of 3.0 wt.% Ru NPs into the hollow ZIF-67 porous metal-organic framework (MOF) yielded highly stable with good morphology and porous. Significant findingsRu NPs dispersed on carbonized Co3O4/NC have a hollow porous structure with a convoluted nano restricted inner region between Co3O4 and NC, allowing for a large number of accessible active sites and easy mass transfer and controlling the carbonized temperature can change the composition of Co3O4/NC heterostructures. These hollow porous carbon materials show much higher turnover frequency during a very short time and also high stability after ten cycles for the AB hydrolysis. This carbonized sample of Ru@Co3O4/NC-350 NPs exhibited increased catalyst stability and materials reusability. There is particularly great potential for industrial application of this catalytic system in fuel cells, because of its simple preparation method, the use of relatively cheap metals, and its highly active catalysis.