Manganese-based Metal Organic Framework Research Articles

Flexible and Free-Standing Metal-Organic Framework Nanowire Paper.

Beyond traditional paper, multifunctional nanopaper has received much attention in recent years. Currently, many nanomaterials have been successfully used as building units of nanopaper. However, it remains a great challenge to prepare flexible and freestanding metal-organic framework (MOF) nanopaper owing to the low aspect ratio and brittleness of MOF nanocrystals. Herein, this work develops a flexible and free-standing MOF nanopaper with MOF nanowires as building units. The manganese-based MOF (Mn-MOF) nanowires with lengths up to 100 μm are synthesized by a facile solvothermal method. Through a paper-making technique, the Mn-MOF nanowires interweave with each other to form a three-dimensional architecture, thus creating a flexible and free-standing Mn-MOF nanowire paper. Furthermore, the surface properties can be engineered to obtain high hydrophobicity by modifying polydimethylsiloxane (PDMS) on the surfaces of the Mn-MOF nanowire paper. The water contact angle reaches 130°. As a proof of concept, this work presents two potential applications of the Mn-MOF/PDMS nanowire paper: (i) The as-prepared Mn-MOF/PDMS nanowire paper is compatible with a commercial printer. The as-printed colorful patterns are of high quality, and (ii) benefiting from the highly hydrophobic surfaces, the Mn-MOF/PDMS nanowire paper is able to efficiently separate oil from water.

Unlocking Double Redox Reaction of Metal-Organic Framework for Aqueous Zinc-Ion Battery.

Metal-organic frameworks (MOFs) show wide application as the cathode of aqueous zinc-ion batteries (AZIBs) in the future owning to their high porosity, diverse structures, abundant species, and controllable morphology. However, the low energy density and poor cycling stability hinder the feasibility in practical application. Herein, an innovative strategy of organic/inorganic double electroactive sites is proposed and demonstrated to obtain extra capacity and enhance the energy density in a manganese-based metal-organic framework (Mn-MOF-74). Simultaneously, its energy storage mechanism is systematically investigated. Moreover, profiting from the coordination effect, the Mn-MOF-74 features with stable structure in ZnSO4 electrolyte. Therefore, the Zn/Mn-MOF-74 batteries exhibit a high energy density and superior cycling stability. This work aids in the future development of MOFs in AZIBs.

Preparation of manganese-based metal organic framework (MOF) and its characterization properties

Metal-organic frameworks (MOFs) are produced by the reaction of metal ions and organic linkers with extremely crystalline and porous coordination networks. The applications of MOF cover from gas purification, gas separation, catalysis and super-capacitors. This work reports on the synthesization of metal-organic framework (MOF), using mangan (II) nitrate tetrahydrate as source of metal ions, 2-methylimidazole as organic ligand and ethanol as solvent. The material was prepared using precipitation method, at room temperature for 48 hours. The characterization of this material were carried out including X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The SEM analysis shows an irregular structure with a few petals. XRD shows several peaks, indicating crystallinity of the material, and amorphous state. To study the electrochemical property of the material, Cyclic Voltammetry (CV) was conducted. The cyclic voltammetry result shows peak at 0.23 V, with current output of 0.14 μA, with no changes in peak position as the scanning rate increases from 10 to 100 mV/s.

Ultrathin two-dimensional (2D) manganese-based metal-organic framework nanosheets for selective photocatalytic oxidation of thioether.

The efficiency of photocatalysts depends largely on the accessibility of reaction species to the active centre, the electron transfer and geometric matching between the active surface of the catalyst and reaction species. In this work, we successfully synthesized and designed one two-dimensional Mn(II) MOF with [Mn2(H2L1)(H2O)2(DMF)2]n·(CH3CH2OH)n (HSTC 3) by using MnCl2·4H2O and 5,5'-(anthracene-9,10-diyl)diisophthalic acid (H4L1), in which the adjacent layers are stacked with weak interactions, and the huge gap leads to the interpenetration between layers to form a 2D + 2D → 3D interpenetration frame. Based on the particularity of the structure of HSTC 3, ultrasonic wall breaking methods were tried to successfully peel HSTC 3 into nanosheets (HSTC 3-NS), thus achieving a significant improvement in a series of optoelectronic properties due to exposure to more active centres for HSTC 3-NS. These results significantly enhance the photocatalytic selective oxidation of thioether. This study provides a new insight into the post-synthesis modification of MOF photocatalyst and their application in photocatalytic organic synthesis.

Facile synthesis of cobalt, nickel and manganese-based metal organic framework derived layered double hydroxides on Ni foam as effective binder-free electrodes of energy storage devices

Metal organic framework (MOF) derivatives have attracted intensive attention as the active material of energy storage devices. Layered double hydroxide (LDH) with large surface area, high redox capability and good cycling stability is regard as one of efficient active materials. Developing MOF-derived LDH with multiple metals can possibly achieve excellent surface properties, high electrical conductivity and abundant redox reactions. However, synthesizing MOF-derived LDH is time-consuming and requires high temperature environments. In this work, a simple and time-effective precipitation and etching process is proposed to synthesize MOF-derived LDH on nickel foam (NF) as binder-free electrodes of energy storage devices. The cobalt, nickel and manganese are utilized to design MOF-derived LDH with different metal species and numbers. The trimetallic MOF-derived LDH based on Co, Ni and Mn presents a high specific capacitance (CF) of 1113.7 F/g at 20 mV/s, due to abundant electroactive sites and multiple redox states for carrying out large numbers of redox reactions. The energy storage device composed of the trimetallic MOF-derived LDH and carbon on NF as electrodes presents the maximum energy density of 61.5 Wh/kg at the power density of 750 W/kg, and the CF retention of 92.5% and Coulombic efficiency of 95% after 10,000 charge/discharge cycles.

Pickering high internal phase emulsions stabilized by metal-organic framework nanoribbons

Pickering high internal phase emulsions (HIPEs) stabilized by colloidal particles are of great practical significance in the formulation of food, pharmaceutical, cosmetic, paint products and the chemical oil flooding. Herein, we report that a manganese-based metal–organic framework (MOF) (Mn3(BTC)2 (BTC = 1,3,5-benzenetricarboxylate)) nanoribbons synthesized by a simple solution method can stabilize water-in-oil (W/O) high-viscosity Pickering HIPEs with crude oil as oil phase for more than one month at 43 °C. The Mn3(BTC)2 nanoribbons assemble at the oil/water interface of HIPE, owing to its advantageous structural features with the size of several micrometers, thickness of about 100 nm and amphiphilicity originated from the hydrophilic metal ions and hydrophobic organic ligands. The phase behavior and properties of the as-prepared HIPEs strongly depend on the MOF concentration (CMOF) and internal phase volume fraction of water (Fw) of emulsion. The MOF dispersions and crude oil are miscible into stable W/O HIPEs at Fw = 75 % when the CMOF ranges from 50 ppm to 5000 ppm. More interestingly, the viscosity of W/O emulsions greatly increases as the Fw varying from 50 % to 80 % and a viscosity of 4.5 Pa·s is obtained at CMOF = 2000 ppm and Fw = 80 %, which is nearly 400 times higher than that of crude oil. Moreover, the pressure generated by HIPEs flowing in core is about 40 times more than that of water injection and can remain the highest stable value substantially. These results show that the MOF dispersions are favorable to form stable W/O emulsions with high internal phase volume fraction, which has a great potential in improving oil displacement efficiency of chemical flooding.

Construction of metal-organic framework/cellulose nanofibers-based hybrid membranes and their ion transport property for efficient osmotic energy conversion

The development of advanced nanofluidic membranes with better ion selectivity, efficient energy conversion and high output power density remains challenging. Herein, we prepared nanofluidic hybrid membranes based on TEMPO oxidized cellulose nanofibers (T-CNF) and manganese-based metal organic framework (MOF) using a simple in situ synthesis method. Incorporated T-CNF endows the MOF/T-CNF hybrid membrane with a high cation selectivity up to 0.93. Nanoporous MOF in three-dimensional interconnected nanochannels provides massive ion transport pathways. High transmembrane ion flux and low ion permeation energy barrier are correlated with a superior energy conversion efficiency (36 %) in MOF/T-CNF hybrid membrane. When operating under 50-fold salinity gradient by mixing simulated seawater and river water, the MOF/T-CNF hybrid membrane achieves a maximum power density value of 1.87 W m−2. About 5-fold increase in output power density was achieved compared to pure T-CNF membrane. The integration of natural nanofibers with high charge density and nanoporous MOF materials is demonstrated an effective and novel strategy for the enhancement of output power density of nanofluidic membranes, showing the great potential of MOF/T-CNF hybrid membranes as efficient nanofluidic osmotic energy generators.

Monocarboxylate transporter blockage-enabled lactate redistribution reshapes immunosuppressive tumor microenvironment and enhances chemodynamic immunotherapy

The immunosuppressive tumor microenvironment (TME) hinders T cells infiltration and prevents a sufficient immune response. Monocarboxylate transporter (MCT)-mediated lactate accumulation not only leads to tumor acidification but also recruits immunosuppressive cells, which greatly limits the therapeutic efficacy of immunotherapy. In this work, we report an MCT blockage strategy using a manganese-based metal organic framework (MnMOF) for enhanced chemodynamic immunotherapy. Syrosingopine (Syr) was found to prevent tumor cells from excreting lactate into the extracellular environment via MCT, thus lowering the intracellular pH and increasing the intracellular H2O2 levels. Afterward, the Mn ion-triggered Fenton-like reaction was amplified by the increased H2O2 levels and strongly acidic conditions in tumor cells. The dying tumor cells induced by chemodynamic therapy released damage-associated molecular patterns, promoting the activation and proliferation of T cells. Furthermore, Syr reduced the lactate levels of the extracellular TME to restore immune activity, including the M1 polarization of tumor-associated macrophages, the activation of dendritic cells and cytotoxic T lymphocytes, and a reduction in immunosuppressive cells. Overall, this Syr@PEG-MnMOF74 nanocomplex enhanced chemodynamic immunotherapy and effectively inhibited the invasion and metastasis of CT26 tumors.

Transforming Cold Tumors into Hot Ones with a Metal-Organic Framework-Based Biomimetic Nanosystem for Enhanced Immunotherapy.

Immunotherapy has revolutionized the landscape in clinical tumor therapy, although the response rates in "cold" tumors are relatively low owing to the complex tumor microenvironment (TME). Cyclic guanosine monophosphate-adenosine monophosphate synthase/stimulator of interferon genes (cGAS/STING) pathway-inducing agents can reprogram the TME; however, their applications remain underutilized. Herein, we engineered a facile manganese-based metal-organic framework (Mn-MOF) encapsulating polyphyllin I (PPI) and coated it with red blood cell (RBC) membranes (RBC@Mn-MOF/PPI) that enhanced the cGAS/STING-mediated antitumor immunity. RBC@Mn-MOF/PPI was engineered by camouflaging it with a biomimetic RBC membrane for prolonged blood circulation and immune escape, which was also extended with TME-sensitive properties for triggering the release of PPI and Mn2+ to remodel the suppressive TME and augment antitumor immune responses. Furthermore, RBC@Mn-MOF/PPI helped transform cold tumors into "hot" ones by activating immune cells, as evidenced via dendritic cell maturation, cytotoxic T lymphocyte infiltration, and natural killer cell recruitment, thereby targeting primary and abscopal tumors and lung metastatic nodules. Therefore, our engineered nanosystem represents a novel strategy to transform immunologically "cold" tumors into "hot" ones by activating the cGAS/STING pathway, thereby addressing the major challenges associated with immunotherapy.

The promoting effect of alkali metal and H2O on Mn-MOF derivatives for toluene oxidation: A combined experimental and theoretical investigation

In this work, different alkali metal (Na or K)-doped manganese-based metal–organic framework (Mn-MOF) derivative materials were obtained from Mn-MIL-100 through ex situ posttreatment method, and their catalytic activities were studied by toluene oxidation. A series of characterization results (N2 adsorption–desorption, X-ray absorption spectroscopy, temperature programmed O2 desorption, etc.) showed that Na-doped Mn-MOF derivatives presented larger specific surface area, lower average manganese valence, and better adsorbed oxygen mobility, which displayed higher catalytic activity. Interestingly, both the addition of alkali metal and the introduction of water in the reaction atmosphere promoted the mineralization of toluene, as demonstrated by in situ diffuse reflectance infrared Fourier transform spectroscopy and thermal desorption-gas chromatography-mass spectrometry. Density functional theory calculations further confirmed that alkali metals and H2O were conducive to the adsorption of toluene, benzyl alcohol, benzaldehyde, benzoic acid and O2. This work provides new ideas for developing high-efficiency and water-promotion Mn-based materials for VOC control.

Sodium decavanadate encapsulated Mn-BTC POM@MOF as high-capacity cathode material for aqueous sodium-ion batteries

Aqueous sodium-ion batteries are the promising candidates for large scale energy storage applications owing to their cost effectiveness and environmental safety. However, the development of a stable cathode material with high capacity is still a challenging task for the commercial viability of aqueous electrolyte-based sodium-ion batteries. This work demonstrates the development of a hierarchically nanostructured high-capacity cathode material by encapsulating sodium decavanadate Na6V10O28 (NaDV) in the scaffold of manganese-based metal-organic framework Mn-BTC (where BTC is 1,3,5-benzenetricarboxylic acid) by an in situ synthesis. The uniform distribution of NaDV in the pores of Mn-BTC enables the multielectron redox properties of NaDV whereas the diverse 3D diffusion channels, high surface area, and flexible architecture of Mn-BTC ensure high intercalation capacity by suppressing the agglomeration and providing faster ionic diffusion kinetics in the NaDV@Mn-BTC nano-hybrid cathode material. The Mn-BTC framework not only ensures the stabilization of NaDV but also enhances sodium storage capacity by the involvement of Mn in the redox process. The NaDV@Mn-BTC cathode material exhibits high reversible capacity of 137 mAh/g at 1 C rate. High capacity of this cathode material suggests that the development of these nano-hybrid materials is a feasible approach to design high energy cathode materials for aqueous batteries.

Dye‐encapsulated nanocage‐based metal–organic frameworks as luminescent dual‐emitting sensors for selective detection of inorganic ions

A novel manganese‐based metal–organic framework (Mn‐MOF) with nanocage has been successfully synthesized by pore space partition (PSP) strategy. Benefiting from the ternary inorganic secondary building units (SBUs) of mononuclear, trinuclear, and rare tetranuclear bi‐paddlewheel, the material possesses good stability and abundant open metal sites (OMSs). As far as the organic SBU, the uncoordinated pyridine groups promote the formation of Lewis basic sites (LBSs). The multiple SBUs construct the overall framework with three types of cages which exhibits novel topology. Furthermore, the anionic framework provides the impetus to encapsulate cationic dyes, which facilitates the construction of dual‐emitting luminescent RhB@Mn‐MOF material with self‐calibrating sensing abilities. The composite material features prominent selective detection performance to Fe (III), which is obviously superior to the parent material. Additionally, a Zn‐MOF with similar structure to Mn‐MOF shows selective detection ability to Cu (II) and P2R@Zn‐MOF prepared by dye‐encapsulated has enhanced performance. However, the Mn‐based materials prepared by PSP provide appropriate cage and more active sites enable them obtain better detection ability. Therefore, the synergistic effect of PSP and dye‐encapsulated strategy is beneficial to improve the selective detection performance of the materials to inorganic ions.

Photocatalytic degradation of methylene blue using a manganese based metal organic framework

Herein, we report the hydrothermal synthesis of a stable and porous 3D-supramolecular frame work of manganese. The ligands used for the fabrication of Mn-MOF are 1,5–naphthalene di sulphonic acid and 4,4′-bipyridine. The applicability of the synthesized MOF as a reusable catalyst in the degradation of methylene blue (MB) under visible light has been investigated. Through the intervention of advanced oxidation process, the Mn-MOF exhibits enhanced photocatalytic activity in the presence of hydrogen peroxide. The active species that facilitates the dye degradation are hydroxyl radicals and holes.

Facile Synthesis and Characterization of the Mn-MOF Electrode Material for Flexible Supercapacitors

Abstract Metal-organic frameworks (MOFs) due to their porosity and well-defined structures are considered to be very promising electrode materials for the construction of high-performance supercapacitor (SC). In this paper, manganese-based metal-organic framework (Mn-MOF) were prepared on the surface of carbon cloth (CC) by a facile hydrothermal method. The morphology and structure of the electrode material were characterized by scanning electron microscopy (SEM), X-ray diffractometer (XRD), Fourier-transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). Its electrochemical studies show that the Mn-MOF electrode materials exhibit lower charge transfer resistance, the excellent specific capacitance of 433.5 mF/cm2 in 1.0 M Na2SO4 aqueous solution at the current density of 0.8 mA/cm2. It is noteworthy that the flexible electrode have excellent cycle stability and 105% capacitance retention even after 5000 cycles at a current density of 5 mA/cm2. The excellent electrochemical performance of Mn-MOF/CC flexible electrode materials can be attributed to its three-dimensional porous structure.

Coordinately Unsaturated Manganese-Based Metal-Organic Frameworks as a High-Performance Cathode for Aqueous Zinc-Ion Batteries.

The slow Zn2+ intercalation/deintercalation kinetics in cathodes severely limits the electrochemical performance of aqueous zinc-ion batteries (ZIBs). Herein, we demonstrate a new kind of coordinately unsaturated manganese-based metal-organic framework (MOF) as an advanced cathode for ZIBs. Coordination unsaturation of Mn is performed with oxygen atoms of two adjacent -COO-. Its proper unsaturated coordination degree guarantees the high-efficiency Zn2+ transport and electron exchange, thereby ensuring high intrinsic activity and fast electrochemical reaction kinetics during repeated charging/discharging processes. Consequently, this MOF-based electrode possesses a high capacity of 138 mAh g-1 at 100 mA g-1 and a long life span (93.5% capacity retention after 1000 cycles at 3000 mA g-1) due to the above advantages. Such distinct Zn2+ ion storage performance surpasses those of most of the recently reported MOF cathodes. This concept of adjusting the coordination degree to tune the energy storage capability provides new avenues for exploring high-performance MOF cathodes in aqueous ZIBs.

A voltammetric sensor based on mixed proton-electron conducting composite including metal-organic framework JUK-2 for determination of citalopram

A voltammetric sensor has been developed based on glassy carbon electrode (GCE) modification with nanocomposite consisting of manganese-based metal-organic framework (JUK-2), multi-walled carbon nanotubes (MWCNTs), and gold nanoparticles (AuNPs) for detection of citalopram (CIT). The composition and morphology of JUK-2-MWCNTs-AuNPs/GCE were characterized by X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), energy dispersion spectroscopy (EDS), and scanning electron microscopy (SEM). The electrochemical properties investigated using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) indicated that the fabricated hybrid material exhibits the properties of mixed ion-electron conductor (MIEC). Using staircase voltammetry (SCV), under optimized conditions, the fabricated sensor shows a linear response in three CIT concentration ranges, 0.05–1.0, 1.0–10.0 and 15.0–115.0 μmol L−1, with a detection limit of 0.011 μmol L−1. The JUK-2-MWCNTs-AuNPs/GCE was successfully employed for the determination of CIT in pharmaceutical, environmental waters, and biological samples with satisfactory recoveries (98.6–104.8%).Graphical abstract

Ozone Decomposition by a Manganese-Organic Framework over the Entire Humidity Range.

Ground-level ozone (O3) is one of the main airborne pollutants detrimental to human health and ecosystems. However, the designed synthesis of high-performance O3 elimination catalysts suitable for broadly variable air compositions, especially a variable water vapor content, remains daunting. Herein, we report a new manganese-based metal organic framework, [Mn3(μ3-OH)2(TTPE)(H2O)4]·2H2O (H4TTPE = 1,1,2,2-tetrakis(4-(2H-tetrazol-5-yl)phenyl) ethane), denoted as ZZU-281. ZZU-281 catalyzes O3 decomposition with a nearly constant 100% working efficiency over the entire humidity range from dry (≤5% relative humidity (RH)) to high humidity (90% RH). We found that the maintainable coordinated water molecules and OH groups are activated by Mn2+, becoming active sites for O3 transfer to O2 with a low activation energy. The unique open channels, water retainability, and water stability of ZZU-281 further support the high catalytic performance. This work opens a new avenue for designing efficient catalysts for O3 elimination in practice.

Efficient electrochemical synthesis of a manganese-based metal–organic framework for H2 and CO2 uptake

Electrochemical synthesis, from manganese strips and dissolved linker, of a new amine-containing manganese-based metal–organic framework with enhanced CO2 uptake.

Manganese-Based Metal Organic Framework from Spent Li-Ion Batteries and its Electrochemical Performance as Anode Material in Li-ion Battery

Herein, we report a method of recycling spent lithium-ion batteries (LIBs) cathode materials by utilizing them as a metal feedstock for the synthesis of Mn-based metal-organic frameworks (Mn-MOF). Spent cathodes were converted to manganese salts using acids (HCl and H2SO4) and reacted with commercial benzene-1,4-dicarboxylic acid (H2BDC), as an organic linker. The LIB-derived metal salts were compared to commercial available MnCl2 salt in the formation of Mn-MOFs. Mn-MOFs from spent LIBs (MOF(Cl2) and Mn-MOF(SO4)) exhibited similar morphological, structural and textural properties when compared to that obtained from commercial MnCl2 salt. HCl obtained MOF (Mn-MOF(Cl2)) was analysed for electrochemical properties due to its superior structural properties. It achieved coulombic efficiency of approximately 99% and discharge capacity of 1355 mAh g−1 as compared to Mn-MOF obtained using commercial salt (Mn-MOF(Com)) with a discharge capacity of 772.55 mAh g−1 at 100 cycles. The developed LIBs recycling strategy has the potential for contributing to existing LIBs recycling strategies and as well to the circular economy.

Postsynthetic Metalated MOFs as Atomically Dispersed Catalysts for Hydroformylation Reactions.

A manganese-based metal-organic framework with dipyrazole ligands has been metalated with atomically dispersed Rh and Co species and used as a catalyst for the hydroformylation of styrene. The Rh-based materials exhibited excellent conversion at 80 °C with complete chemoselectivity, high selectivity for the branched aldehyde, high recyclability, and negligible metal leaching.