Dual Metal-organic Frameworks Research Articles

Enhanced bioelectrochemical performance of microbial fuel cell with titanium dioxide-attached dual metal organic frameworks grown on zinc aluminum - layered double hydroxide as cathode catalyst

In this study, a three-step distributed feeding method was used to prepare TiO2-attached dual CoZn-metal organic frameworks growing on ZnAl-layered double hydroxide (TiO2@ZIF-67/ZIF-8@ZnAl-LDH) as cathode catalyst of microbial fuel cell (MFC). The composite material was a composite core–shell structure constructed by multi-layer coating with sheet-like ZnAl-LDH as the base, dual MOFs as the magnetic core and TiO2 as the rough surface. The composite material had crystal planes (009), (110), (101) interface. The rough surface, core–shell core and polyhedral structure of TiO2@ZIF-67/ZIF-8@ZnAl-LDH were observed. The complete distribution of Ti, Zn, Al, and Co in the material was observed and offered active sites. The contents of Ti (15.97 %), Al (5.53 %), Na (5.04 %), N (3.52%), Zn (1.47 %) were found out. TiO2@ZIF-67/ZIF-8@ZnAl-LDH was excellent in electrochemical activity and the maximum power density was 409.6 mW/m2, the stable continuous output voltage was 538.4 mV for 8 d.

A dual metal-organic framework strategy for synthesis of FeCo@NC bifunctional oxygen catalysts for clean energy application

Developing high efficient bifunctional oxygen electrocatalysts for clean energy applications like Zin-air battery (ZAB) is highly desired, because it would reduce the cost and speed up the practical application of ZAB. Here we use a dual metal–organic framework (MOF) synthesis strategy to prepare the N-doped carbon supported bimetallic FeCo nanoparticle catalysts (marked as [email protected]) by pyrolysis of ZnCo-ZIF/MIL-101(Fe) composite. The [email protected] exhibits remarkable electrocatalytic activity for ORR with half-wave potential of 0.89 V vs. the reversible hydrogen electrode (RHE) and robust durability for both ORR and OER (oxygen reduction reaction and oxygen evolution reaction), which is attributed to the generation of Fe0.26Co0.74 crystalline phase and mesopores due to the dual-MOF synthesis strategy. The rechargeable ZAB based on [email protected] air electrode shows a maximum energy density of 139.6mW·cm−2 and excellent cyclic stability over 130 h, significantly surpassing the Pt and Ir-based ZAB. The present work provides a useful dual-MOF synthesis strategy for preparing high-performance multifunctional catalysts for ORR, OER and hydrogen evolution reaction (HER).

Programmed Catalytic Therapy-Mediated ROS Generation and T-Cell Infiltration in Lung Metastasis by a Dual Metal-Organic Framework (MOF) Nanoagent.

Nano-catalytic agents actuating Fenton-like reaction in cancer cells cause intratumoral generation of reactive oxygen species (ROS), allowing the potential for immune therapy of tumor metastasis via the recognition of tumor-associated antigens. However, the self-defense mechanism of cancer cells, known as autophagy, and unsustained ROS generation often restricts efficiency, lowering the immune attack, especially in invading metastatic clusters. Here, a functional core-shell metal-organic framework nanocube (dual MOF) doubling as a catalytic agent and T cell infiltration inducer that programs ROS and inhibits autophagy is reported. The dual MOF integrated a Prussian blue (PB)-coated iron (Fe2+)-containing metal-organic framework (MOF, MIL88) as a programmed peroxide mimic in the cancer cells, facilitating the sustained ROS generation. With the assistance of Chloroquine (CQ), the inhibition of autophagy through lysosomal deacidification breaks off the self-defense mechanism and further improves the cytotoxicity. The purpose of this material design was to inhibit autophagy and ROS efficacy of the tumor, and eventually improve T cell recruitment for immune therapy of lung metastasis. The margination and internalization-mediated cancer cell uptake improve the accumulation of dual MOF of metastatic tumors in vivo. The effective catalytic dual MOF integrated dysfunctional autophagy at the metastasis elicits the ~3-fold recruitment of T lymphocytes. Such synergy of T cell recruitment and ROS generation transported by dual MOF during the metastases successfully suppresses more than 90% of tumor foci in the lung.

Improving oxygen reduction reaction of microbial fuel cell by titanium dioxide attaching to dual metal organic frameworks as cathode

In this study, a two-step simple distributed feeding method was used to prepare the core–shell nanocomposite dual metal organic frameworks (D-MOFs, TiO2@ZIF-67/ZIF-8). There were three obvious peaks (011), (112), (222) interface in D-MOFs core, which fully showed that ZIF-67/ZIF-8 crystal core was successfully synthesized. The morphology of composite material was core–shell structure with a rough surface, and Ti, Co, Zn, Al were uniformly distributed on the surface. TiO2@ZIF-67/ZIF-8 also had excellent electrochemical activity and the maximum power density of TiO2@ZIF-67/ZIF-8 microbial fuel cell (MFC) was 341.506 mW/m2, which was 1.30 times of ZIF-67/ZIF-8-MFC (262.144 mW/m2) and 2.07 times of ZIF-67-MFC (164.836 mW/m2). And the continuous output voltage of TiO2@ZIF-67/ZIF-8-MFC was 413.43 mV, which could maintain stable voltage output for 8.3 days. D-MOFs as the core of composites ensured the integrity, stability and high activity of materials; Rough TiO2 as the surface of the material provided surface area and reaction center.

Engineering heterostructured Co0.7Fe0.3@Co doped leaf-like carbon nanoplates from dual metal-organic frameworks for high-efficiency oxygen reduction reaction in microbial fuel cell

Microbial fuel cell (MFC) satisfies the needs of power generation and pollutants removal but still requires active electrocatalysts to accelerate cathodic oxygen reduction reaction (ORR). Metal-nitrogen-carbon materials (M − NCs) derived from Prussian blue analogues (PBAs), known for low cost and high yield, fail with satisfactory surface structure and their intrinsic activity requires to be further improved. Here, a MOF@MOF precursor (Co-ZIF-L@CoFe PBA-1, MOF: metal-Organic framework) is skillfully fabricated by utilizing two-dimensional (2D) leaf-like cobalt-based zeolitic-imidazolate framework (Co-ZIF-L) as the mother MOF to give birth to cobalt iron Prussian blue analogue (CoFe PBA) by adjusting reaction time and solvents with a ligand exchange method. After carbonization, Co-ZIF-L@CoFe PBA-1 transforms into a leaf-shaped carbon nanoplate with heterostructured CoFe alloy and Co (Co 0.7 Fe 0.3 @Co-NC-1), which exhibits outstanding ORR activity and high MFC performance (2486 ± 56 mW m -2 ) compared with Co-NC and Co 0.7 Fe 0.3 -NC derived from Co-ZIF-L and leaf-like CoFe PBA, respectively. The interfacial Co 0.7 Fe 0.3 @Co efficiently optimizes electronic structure for fast electrons transfer and the porous carbon matrix provides desirable surface structure for oxygen transfer, synergistically triggering a high ORR activity. Our work offers new insights for controllable preparation of PBAs-based dual-MOFs precursors and provides a feasible avenue for enhancing the activity of PBAs-based M − NCs catalysts. • Co-ZIF-L gives birth to Co-Fe PBA through a ligand exchange method. • The amount of Co-Fe PBA on Co-ZIF-L can be adjusted by reaction time and solvents. • The ORR activity is attributed to the integration of dual-MOF precursor. • The maximum power density of Co 0.7 Fe 0.3 @Co-NC-1 air cathode is 2486 ± 56 mW m 2 .

Fe-N4 Doped Carbon Nanotube Cathode Catalyst for PEM Fuel Cells.

The earth-abundant iron and nitrogen doped carbon (Fe-N-C) catalyst has great potential to substitute noble metal catalysts for oxygen reduction reaction (ORR) in H2-O2 proton exchange membrane fuel cells (PEMFCs). Herein, we report the preparation of Fe-N4 moiety doped carbon nanotubes (CNTs) by ball milling and two-step pyrolysis with dual metal-organic frameworks (MOFs) as the precursor. This catalyst shows high ORR catalytic performance and stability. Different from traditional inorganic iron sources, the MOF structure can effectively prevent the iron metal from aggregating during pyrolysis. In PEMFC, the catalyst shows high current density (0.39 A/cm2 at 0.7 V) and power density (850 mW/cm2). Such a method brings inspiration for the reasonable design of FeNC catalysts with high catalytic activity for H2-O2 PEMFCs.

1D/2D nanoconfinement FexOy and nitrogen-doped carbon matrix for catalytic self-cleaning membranes removal for pollutants

Catalytic performance and practical applications of catalysts are two key problems in wastewater treatment through activating peroxymonosulfate (PMS). Herein, 1D/2D nitrogen-doped carbon matrix with confined FexOy was firstly developed through in-situ pyrolysis of dual metal-organic frameworks (named as ZIF@MILs-20). Subsequently, graphene oxide (GO) supported composite membranes were constructed through intercalating ZIF@MILs-20 into adjacent GO. Studies have proven that enriched oxygen vacancies, confined FexOy and 1D/2D hierarchically porous structures of ZIF@MILs-20 were favorable for the elimination of norfloxacin (NX) through a synergistic “trap-and-zap” strategy for PMS activation. As expected, 99.4% NX over ZIF@MILs-20/PMS system was degraded after 40 min. Further, abundant oxygen-containing groups on GO composite membranes strongly improved the wettability of catalysts that shorten the reaction distance between reactive oxidative species (ROS) and active sites. Thus ZIF@MILs-20/GO membrane provided instantaneous elimination of norfloxacin for up to 10 h under flow-through filtration. Notably, ZIF@MILs-20/GO membrane realized the membrane filtration-catalytic oxidation of organics, powerfully overcoming the membrane fouling with a stable flux of 156.3 L·m−2·h−1·bar−1. Besides, singlet oxygen (1O2) was proven that dominantly contributed to the NX degradation. In short, the construction of catalytic membranes provides a new idea for wastewater treatment.

Ratiometric fluorescence for sensitive detection of phosphate species based on mixed lanthanide metal organic framework.

Phosphate (PO43-) plays a major role in aquatic ecosystems and biosystems. Developing a highly sensitive and selective ratiometric fluorescence probe for detection of PO43- is of great significance to the ecological environment and human health. In this work, a novel dual lanthanide metal organic framework was synthesized via hydrothermal reaction based on Tb3+ and Ce3+ as the center metal ions and terephthalic acid as the organic ligand (designated as Tb-Ce-MOFs). The fluorescence of Tb-Ce-MOFs shows emission at 375nm. In the presence of PO43-, with increased concentration of PO43-, the fluorescence intensity of Tb-Ce-MOFs at 500nm and 550nm increased, while the intensity at 375nm was reduced. Hence, ratiometric fluorescence detecting of PO43- can be achieved by measuring the ratio of fluorescence at 550nm (FL550) to 375nm (FL375) in the fluorescent spectra of the Tb-Ce-MOFs. In this sensing approach, the Tb-Ce-MOFs probe exhibits highly sensitive and selective for detection of PO43-. The limit of detection is calculated to be 28nM and the detection range is 0.1 to 10μM. In addition, the Tb-Ce-MOFs were used in the detection of PO43- in real samples. We design and synthesize a mixed lanthanide metal organic framework fluorescence probe (Tb-Ce-MOFs) for ratiometric fluorescence for the detection of PO43- based on Tb3+ and Ce3+ as the center metal ions and terephthalic acid as the organic ligand.

Dual MOFs template-directed fabrication of hollow-structured heterojunction photocatalysts for efficient CO2 reduction

The hollow-structured C-In 2 O 3 @MO (MO = ZnO, Co 3 O 4 , and ZnCo 2 O 4 ) heterojunction photocatalysts are fabricated by the core–shell structured dual MOF template-directed strategy. The obtained photocatalysts exhibit high performance for CO 2 photoreduction, due to the suitable energy band matching structure and high solar light unilization. • A dual MOFs template-directed strategy for fabricating heterojunction photocatalysts is firstly developed. • A series of C-In 2 O 3 @MO (MO = ZnO, Co 3 O 4 , and ZnCo 2 O 4 ) heterojunctions are fabricated. • The sutiable energy matching and hollow structure of the C-In 2 O 3 @ZnCo 2 O 4 promotes CO 2 photoreduction activity. Developing efficient photocatalysts for CO 2 reduction into value-added chemical feedstocks is of significance. Heterojunction photocatalysts are promising candidates but still suffering from the insufficient electron-hole pair separation issues. Herein, a strategy that dual metal–organic frameworks (MOFs) template-directed fabrication of carbon-supported heterojunction, C-In 2 O 3 @MO (MO = ZnO, Co 3 O 4 , and ZnCo 2 O 4 ) with tunable band matching structure was developed. The resultant hollow- structured C-In 2 O 3 @ZnCo 2 O 4 shows high CO 2 reduction activity towards CO (44.1 μmol g 1 h −1 ) with a selectivity of 66%. The superior performance of this material could be ascribed to the suitable energy band matching and efficient internal charge transfer on p-n heterojunction, which facilitates electron-hole separation. Meanwhile, the hollow cavity not only improved light-harvesting capability through multiple light reflection and scattering in the internal voids but also provided large surface area for exposing active sites to promoting the activation of CO 2 . This study thus proposes a feasible approach to adjust the heterojunction structure of photocatalysts to achieve efficient CO 2 reduction reaction.

Highly sensitive and stable self-powered biosensing for exosomes based on dual metal-organic frameworks nanocarriers

Biofuel cells (BFCs)-based self-powered biosensors suffer from the limited stability of bioenzymes. Meanwhile, the poor performance of self-powered biosensors affects the sensitivity of biosensing, thus, it is significant and challenging to improve their stability and sensitivity. In our work, a BFC-based self-powered biosensor, with simultaneously enhanced stability and sensitivity, was constructed utilizing dual metal-organic frameworks (MOFs) as the carriers of the bioenzyme and the electroactive probe, respectively. Anodic enzyme, glucose dehydrogenase (GDH), was encapsulated in zeolitic imidazolate framework-8 (ZIF-8) to form GDH@ZIF-8 composites, enhancing the catalytic activity and stability of GDH. Meanwhile, another zirconium metal-organic frameworks (UiO-66-NH2) loaded with electroactive molecules (K3[Fe(CN)6]) served as nano-enrichment carriers and improved the capability of the cathode to accept electrons from the anode, further improving the sensitivity of the as-proposed biosensor. Herein, the “signal-on” BFC-based self-powered biosensing of exosomes, the model analyte, with excellent stability and outstanding sensitivity was realized with the assistance of dual MOFs, and the detection limit was down to 300 particles mL−1 (based on 3s/k), which was superior to those previously reported in literatures. Furthermore, the developed protocol was capable of detecting exosomes derived from cancer cells in complex biological samples. Overall, in this work the enhancement of both stability and sensitivity has been achieved by utilizing two types of MOFs, which laid the foundation for expanding the applications of BFC-based self-powered biosensors.

Synergetic catalytic behavior of dual metal-organic framework coated hematite photoanode for photoelectrochemical water splitting performance

The performance of oxide photoanodes constructed with hematite (Fe2O3) nanostructures is among the best for low-cost photoelectrochemical water-splitting cells. However, due to limited light absorption capacity, a high photogenerated charge carrier recombination rate, and sluggish surface oxygen evolution reaction (OER) kinetic on the surface, the photocurrent density generated by bare hematite is lower than the theoretical value. To overcome these limitations, we fabricate hematite photoanodes with a dual metal–organic framework (MIL-88B@ZIF-67) coating, which greatly enhances light harvesting efficiency and the intrinsic charge carrier transport rate. Owing to these spectacular advantages, the optimized Fe2O3/MIL-88B@ZIF-67 photoanode affords a stable photocurrent density of 2.52 mA∙cm−2 at 1.23 V vs. a reversible hydrogen electrode (RHE) under one sun irradiation. The photocurrent density is significantly higher than that achieved with a bare Fe2O3 photoanode (0.27 mA∙cm−2). Most importantly, the cathodic shift of the Fe2O3/MIL-88B@ZIF-67 photoanode (119 mV) is larger than that of pristine Fe2O3. The measured incident photon-to-electron conversion efficiency of the Fe2O3/MIL-88B@ZIF-67 photoanode reaches 30.85% at 330 nm. A photocurrent decay of only 5% over 20 h indicates that the photoanode is also extraordinarily stable. We find that it is crucial to precisely control the number of MIL-88B@ZIF-67 coating layers to reduce the charge carrier recombination rate. We expect that our approach will be effective for the design of efficient and stable photoanodes for PEC water splitting.

Tailored core‒shell dual metal–organic frameworks as a versatile nanomotor for effective synergistic antitumor therapy

Malignant tumor has become an urgent threat to global public healthcare. Because of the heterogeneity of tumor, single therapy presents great limitations while synergistic therapy is arousing much attention, which shows desperate need of intelligent carrier for co-delivery. A core‒shell dual metal–organic frameworks (MOFs) system was delicately designed in this study, which not only possessed the unique properties of both materials, but also provided two individual specific functional zones for co-drug delivery. Photosensitizer indocyanine green (ICG) and chemotherapeutic agent doxorubicin (DOX) were stepwisely encapsulated into the nanopores of MIL-88 core and ZIF-8 shell to construct a synergistic photothermal/photodynamic/chemotherapy nanoplatform. Except for efficient drug delivery, the MIL-88 could be functioned as a nanomotor to convert the excessive hydrogen peroxide at tumor microenvironment into adequate oxygen for photodynamic therapy. The DOX release from MIL-88-ICG@ZIF-8-DOX nanoparticles was triggered at tumor acidic microenvironment and further accelerated by near-infrared (NIR) light irradiation. The in vivo antitumor study showed superior synergistic antitumor effect by concentrating the nanoparticles into dissolving microneedles as compared to intravenous and intratumoral injection of nanoparticles, with a significantly higher inhibition rate. It is anticipated that the multi-model synergistic system based on dual-MOFs was promising for further biomedical application.

Copper//terbium dual metal organic frameworks incorporated side-by-side electrospun nanofibrous membrane: A novel tactics for an efficient adsorption of particulate matter and luminescence property

Particulate matters with different sizes (PM2.5 and PM10) in the air have become a supreme environmental concern to human health globally. Herein, the magnetic-luminescent Cu//Tb dual metal-organic frameworks (MOFs) incorporated side-by-side nanofibrous (SBS-NFs) membrane has been successfully fabricated via the electrospinning technique with the self-designed nozzle for the first time. The fabricated SBS-NFs membrane was composed of Cu-MOF/PAN at one side and Tb-MOF/PAN at another side with their individual characteristics. The Cu-MOF was used to improve the filtration efficiency and reduced the pressure drop by enhancing the electrostatic interaction, whereas, Tb-MOF was incorporated to investigate the PM adsorption process through the changes in luminescence intensity. Compared to polyacrylonitrile nanofibers (PAN NFs), Cu//Tb dual MOFs incorporated SBS-NFs membrane showed an enhanced filtration efficiency (90.2%) and a reduced pressure drop (60.7 Pa) when sodium chloride (NaCl) aerosols with particle size less than 300 nm were used for testing. As a result of the filter test using car exhaust, Cu//Tb SBS-NFs membrane still maintained >91% PM removal efficiency for >30 h. In addition, it was confirmed that the luminescence intensity over the PM adsorption time was linearly weakened. Therefore, Cu//Tb dual MOFs incorporated SBS-NFs membrane can be used for a variety of applications.

Interface engineering of zeolite imidazolate framework−8 on two-dimensional Al−metal−organic framework nanoplates enhancing performance for simultaneous capture and sensing tetracyclines

The increasing misgivings of environmental pollution derived from antibiotic residues make it imperative to explore a bifunctional platform for synchronous monitoring and removal of antibiotics. Herein, zeolite imidazolate framework-8 (ZIF-8) is anchored on two-dimensional (2D) amino-functionalized Al-metal organic framework (NH2-MIL-53(Al)) nanoplates to construct a dual metal–organic frameworks smart platform (ZIF-8/NH2-MIL-53(Al)) for simultaneous capture and fluorescence sensing of tetracyclines (TCs). ZIF-8 nanoparticles anchored on 2D nanoplates having a smaller size and a larger specific surface area boost the adsorption capabilities (561, 533, 526 and 578 mg g−1 for doxycycline (DOX), tetracycline (TET), oxytetracycline (OTC) and chlortetracycline (CTC), respectively). Notably, the pyridine N of ZIF-8 cooperated with the abundant NH2 on the surface of NH2-MIL-53(Al) exhibits high affinity toward TCs, remarkably enhancing the sensitivity by facilitating the photo-induced electron transfer and the inner-filter effect. The LODs (1.2 μg L−1 for TET, DOX, OTC and 2.2 μg L−1 for CTC, respectively) are at least 10-fold lower than those of NH2-MIL-53(Al) and are comparable or superior to those of reported sensors. The dual metal–organic frameworks smart platform presents satisfactory reliabilities and accuracies for detecting TCs in real samples, which anticipates new routes to develop integrated systems for simultaneous capture and detection of organic pollutants.

Fluorinated ZnFeIII Hollow Metal-Organic Framework as a 19F NMR Probe for Highly Sensitive and Selective Detection of Hydrogen Sulfide.

Hydrogen sulfide (H2S) is considered as a highly toxic environmental pollutant and an important signal transmitter in physiological processes, and the selective and reliable detection of H2S is of great concern and remains challenging. Herein, we report a smart sensitive “off–on” 19F NMR sensor for H2S by partially introducing a fluorinated ligand to construct a hollow dual metal–organic framework (MOF) nanosystem, F-ZnFeIII hMOF, in which the fluorinated ligand acts as the 19F signal source but is initially quenched due to the strong paramagnetic relaxation enhancement (PRE) effect from neighboring Fe3+ nodes. Upon exposure to sulfide ions, reduction of Fe3+ to Fe2+ is specifically triggered, which attenuates PRE efficiency, thus turning on the 19F NMR signal. The unique hollow MOF architecture benefits the mobility of 19F atoms, thereby improving the response sensitivity. Meanwhile, the desirable H2S-sorption feature and appropriate redox potential of Fe3+/Fe2+ account for the favorable selectivity. The increase in the 19F signal is linear with the concentration of sulfide in the range of 20 to 150 μM with a detection limit of 2.8 μM. The probe is well demonstrated by analyzing H2S in complex matrixes such as biological and foodstuff samples.

Site-specific MOF-based immunotherapeutic nanoplatforms via synergistic tumor cells-targeted treatment and dendritic cells-targeted immunomodulation

An efficient antitumor immune response relies on multiple cells-based process including tumor cells-targeted immunogenicity increment, dendritic cells (DCs)-targeted vaccine delivery and T cells-mediated tumor elimination. Only limited immune efficacy could be achieved by strengthening the function of single type of cells. Therefore, building an effective immunotherapeutic nanoplatform by simultaneously modulating the functions of multiple cells involved in immune process is urgently demanded. However, it is challenging to modulate multiple cells since the on-demand delivery of diverse agents to different cells is restricted by inherent different target sites. Herein, as a proof of concept, dual tailor-made metal organic framework (MOF) nanoparticles based on zeolitic imidazolate framework-8 (ZIF-8) are designed to comprehensively enhance the immunotherapy via the spatiotemporal cooperation of various therapeutic agents including photothermal agent IR820, adjuvant imiquimod (R837) and immunomodulator 1-methyl-d-tryptophan (1 MT). On one hand, IR820@ZIF-8 is modified with hyaluronic acid for realizing tumor-targeted photothermal therapy, accompanied with the release of tumor antigens. On the other hand, (R837+1 MT)@ZIF-8 is modified with mannan for achieving DCs-targeted immune amplification. The synergistic tumor cells-targeted treatment and DCs-targeted immunomodulation can efficiently overcome two major obstacles in immunotherapy: inadequate activation of immune response and immune evasion, offering powerful platform against invasive malignancy and rechallenged tumors.

Gas-solid two-phase flow (GSF) mechanochemical synthesis of dual-metal-organic frameworks and research on electrochemical properties.

As an alternative approach for conventional mechanochemical synthesis, a novel gas–solid two-phase flow (GSF) synthetic technique for the mechanochemical synthesis of dual metal–organic frameworks (DMOFs) was reported for the first time. The prepared CoMn2(BTC)2 was characterized by FT-IR, DTA, TG/DTG, and XRD studies. The results indicated that CoMn2(BTC)2 (BTC = 1,3,5-benzenetricarboxylate) was successfully synthesized after 10 min at a rate of 60 kg h−1. CoMn2O4 microspheres were also prepared via the CoMn2(BTC)2 precursor method and characterized using FT-IR, XPS, XRD, SEM, EDS, and BET methods. The electrochemical properties of the as-prepared CoMn2O4 were investigated, and the GSF results showed that the microsphere electrodes of CoMn2O4 had a high specific capacitance (969 F g−1) at a current density of 1 A g−1 in 3 M aqueous KOH solution.

Hierarchically Porous Multimetal‐Based Carbon Nanorod Hybrid as an Efficient Oxygen Catalyst for Rechargeable Zinc–Air Batteries

AbstractThe lack of efficient strategies to address the intrinsic activity, site accessibility, and structural stability issues of metal‐carbon hybrid catalysts is restricting their real‐world implementation on the basis of rechargeable zinc–air batteries. Herein, a dual metal–organic frameworks (MOFs) pyrolysis strategy is developed to regulate the intrinsic activity and porous structure of the derived catalysts, where a Fe2Ni_MIL‐88@ZnCo_zeolitic imidazolate framework (ZIF), with a hierarchically porous structure, multifunctional components, and an integrated architecture, acts as an ideal precursor to obtain multimetal based porous nanorod (FeNiCo@NC‐P). Benefitting from the synergetic effect of the multimetal components, facilitated reactant accessibility, and the well‐retained integrated structure, the resultant FeNiCo@NC‐P catalyst exhibits an oxygen reduction reaction half‐wave potential of 0.84 V as well as an oxygen evolution reaction potential of 1.54 V at 10 mA cm–2. Furthermore, the practical application of FeNiCo@NC‐P in the zinc–air battery displays a low voltage gap and long‐term durability (over 130 h at a current density of 10 mA cm–2), which outperforms the commercial noble metal benchmarks. This work not only affords a competitive bifunctional oxygen electrocatalyst for zinc–air batteries but also paves a new way to design and fabricate MOF‐derived materials with tunable catalytic properties.

Electrochemiluminescence immunosensor of “signal-off” for β-amyloid detection based on dual metal-organic frameworks

In this work, a “signal-off” sandwich electrochemiluminescence (ECL) immunosensor was fabricated for ingenious detection of Alzheimer's disease marker β-amyloid (Aβ) based on dual metal-organic frameworks (dual-MOFs), which included NH2-UiO-66 and MIL-101. Dual-MOFs with high porosity and plentiful functional groups can increase the biomolecules binding rate, and through the synergy with the different materials can effectively amplify the inherent properties of the material itself. Ru(bpy)32+ was capsulated in NH2-UiO-66 as luminophor, the complex possessed steady and excellent luminescence efficiency as well as large specific surface area to load sufficient antibodies. MoS2 quantum dots (MoS2 QDs) combined with MIL-101 via Au–S bond. MIL-101@Au–MoS2 QDs was used for the label of secondary antibodies (Ab2) to quench the ECL signal of Ru(bpy)32+/NH2-UiO-66. The amount of Ab2-MIL-101@Au–MoS2 QDs bound to antigen will gradually accrue with the increase of the concentration of Aβ, which led to “signal-off” for accurate estimation of Aβ. Under optimal conditions, the developed assay for Aβ detection demonstrated a wide linear range of 10−5 ng mL−1 to 50 ng mL−1 and the detection limit was as low as 3.32 fg mL−1 (S/N = 3). The cooperation of dual-MOFs has potential as a universal strategy for quantitative analysis of other targets.

Dual Metal-Organic Framework Heterointerface.

Herein, a core–shell dual metal–organic framework (MOF) heterointerface is synthesized. The Prussian blue (PB) MOF acts as a core for the growth of a porphyrin-doped MOF which is named PB@MOF. Porphyrins can significantly enhance the transfer of photoinspired electrons from PB and suppress the recombination of electrons and holes, thus enhancing the photocatalytic properties and consequently promoting the yields of singlet oxygen rapidly under 660 nm illumination. PB@MOF can exhibit a better photothermal conversion efficiency up to 29.9% under 808 nm near-infrared irradiation (NIR). The PB@MOF heterointerface can possess excellent antibacterial efficacies of 99.31% and 98.68% opposed to Staphylococcus aureus and Escherichia coli, separately, under the dual light illumination of 808 nm NIR and 660 nm red light for 10 min. Furthermore, the trace amount of Fe and Zr ions can trigger the immune system to favor wound healing, promising that PB@MOF achieves the rapid therapy of bacterial infected wounds and environmental disinfection.