Bifunctional Metal Organic Framework Research Articles

In-situ active sites analysis of bifunctional metal-organic frameworks for coupled adsorption and electrochemical oxidation of PPCPs

Pharmaceuticals and personal care products (PPCPs) pose a significant wastewater pollution concern. While electrochemical oxidation is promising, it struggles with slow mass transfer. To address this, we propose a novel strategy utilizing bifunctional metal–organic frameworks (MOFs) that couple an adsorbent with an electrocatalyst. The real active sites within iron-based MOFs responsible for the adsorption of PPCPs are MIL-101(Fe) molecules, while the in-situ formed active sites, α-FeOOH, accelerate the charge transfer under bias, contributing to the electrooxidation of PPCPs. The rapid destruction of adsorbed organics on the dual-functional electrode surface enables to release adsorption sites. This, in turn, paves the way for fast and efficient re-adsorption of PPCPs molecules, consequently promoting mass transfer. Iron-based MOFs exhibit excellent adsorption capacity (∼60 mg g−1 for sulfosalicylic acid, ∼15 mg g−1 for acetaminophen) and electrooxidation ability (94 % removal in 2 h, 31.2 kWh kg−1 COD) with good stability in realistic pharmaceutical wastewater treatment. This study offers a novel strategy for removing PPCPs using molecular electrocatalysts and provides new insights for designing and constructing MOFs for refractory wastewater treatment.

Retraction Note: A Bifunctional Metal–Organic Framework Based on Linear Trinuclear Clusters for Solvent-Free Aldehyde Cyanosilylation and Growth Inhibition of Human Breast Cancer Cells

Retraction Note: A Bifunctional Metal–Organic Framework Based on Linear Trinuclear Clusters for Solvent-Free Aldehyde Cyanosilylation and Growth Inhibition of Human Breast Cancer Cells

Interfacial and Electronic Modulation of M-Bridged Heterostructures with L-Tryptophan and Transition Metallic Oxides: Enhancing Corrosion Resistance and Photocatalytic Activity.

Despite remarkable advancements in multilayer composite materials, achieving controlled growth on stationary platforms for optimal corrosion protection and photocatalytic capabilities remains a challenge. In this study, we introduce an innovative approach by integrating bifunctional metal-organic frameworks (MOFs) into plasma-electrolyzed layers made on AZ31 Mg alloy. Metallic oxides of Zr, Ti, and W serve as new pivotal centers for MOF formation, while L-tryptophan (Trp) acts as an organic linker. This innovative approach establishes an efficient electron transport system that acts as a functional pathway for creating highly effective and versatile materials. The tunable structure of the MOF/plasma electrolyzed layer enables it to concurrently display electrochemical stability and photocatalytic activity for the photodegradation of organic pollutants. Remarkably, the WOF complex emerges as a standout performer, effectively shielding the substrate from corrosive anion attacks. This sample showcases exceptional photocatalytic efficiency of 99.61% for crystal violet solution, with sustained performance after five cycles and a 72 h corrosion test (96.55% and 98.39% degradation, respectively). Moreover, DFT calculations elucidate the fundamental bonding modes between MOFs and inorganic constituents, delivering comprehensive insights into their structural formation. Our research addresses the critical challenge of achieving controlled growth for enhanced corrosion resistance and photocatalytic activity, demonstrating a novel pathway for creating multifunctional materials with practical applications across various fields.

Bifunctional Fe-MOF@Fe3O4NPs for colorimetric and ratiometric fluorescence detection of uric acid in human urine

Nanozymes as a substitute for natural enzymes have attracted many attention owing to their high stability, low cost, and satisfactory catalytic activity. In this study, a new dual-readout detection strategy was proposed for colorimetric and ratiometric fluorescence detection of uric acid (UA) based on bifunctional metal–organic framework nanocomposite (Fe-MOF@Fe3O4NPs), which functions as fluorescent indicators as well as peroxidase mimics. In the presence of uricase, the decomposition of UA can produce H2O2, and Fe-MOF@Fe3O4NPs catalyzed H2O2 into the OH radicals, which could oxidize o-phenylene-diamine to 2,3-diaminophenazine, accompanied by a fluorescence emission at 600 nm and a UV–vis absorption peak at 450 nm. At the same time, the fluorescence of Fe-MOF@Fe3O4NPs at 460 nmcould be quenched by 2,3-diaminophenazine via Förster resonance energy transfer. Therefore, the fluorescence intensity ratio (I600/I460) and UV–vis absorption intensities are employed to construct the dual-readout biosensor for the determination of UA. The linear range was 0.2–200 μM and the limit of detection for the fluorometric and colorimetric detection were 0.03 μM and 0.18 μM, respectively. Finally, the biosensor was employed to determine UA in urine samples, and satisfactory results were obtained.

Design, transport efficiency and structure-activity relationship of sulfonated poly (aryl ether ketone) proton exchange membrane based on multi-functional MOFs

In this paper, two kinds of metal-organic frameworks (MOFs) with proton conduction capability were successfully prepared and added into sulfonated poly (ether ketone sulfone) (C-SPAEKS) by organic-inorganic blending. Then two different series of proton exchange membranes (PEMs) were fabricated. The template used in MOFs was UiO-66-NH2 (UN), by introducing sulfonic acid groups and imidazole groups on the template, additional proton sources and proton transport sites were constructed. Such multifunctional MOFs contributed greatly to the proton transport efficiency and structure-activity relationship of C-SPAEKS. The sulfonic acid functionalized MOFs (USN), sulfonic-acid-imidazole bifunctional MOFs (IUSN) and composite PEMs were characterized by XRD, XPS, FT-IR, 1H NMR and SEM. The prepared PEMs all have excellent proton conductivity, in which the proton conductivity of C-SPAEKS/IUSN-3% could reach 0.234 S cm−1 (80 °C and 100% relative humidity). Nafion117 had a conductivity of 0.105 S cm−1 (80 °C and 100% relative humidity), so C-SPAEKS/IUSN-3% exhibited a great enhancement on proton conductivity. Moreover, the oxidation stability of C-SPAEKS/IUSN-3% membrane was 96.97%, which was 39.32% higher than that of C-SPAEKS. These results all indicated that the as-prepared MOFs have made great contribution to improving the comprehensive properties of the sulfonated poly (aryl ether ketone) proton exchange membrane.

Efficient proton exchange membranes based on bifunctional metal–organic frameworks

Efficient proton exchange membranes based on bifunctional metal–organic frameworks

Constructing bi-functional Ce-MOF on carbon fiber endowing epoxy coating with excellent anti-corrosion and erosion wear resistance

The limited interfacial combination between CF and polymer matrix caused by the chemical inertness of CF surface greatly restricts the protective capability of carbon fiber reinforced polymer coatings (CFRPCs), which could not effectively resist the impact of external forces, especially in the severe and complicated ocean environment (like deep-sea area and splash zone). Hence, it is the crux to enhance the interface compatibility and interface strength between fiber and resin. Based on the reliable compatibility between imidazole and epoxy as well as the corrosion inhibition effects of cerium-based compounds, a kind of bi-functional metal-organic framework (MOF) called the cerium-imidazole framework (Ce-MI) was constructed on the CFs surface via in-situ growth method to improve the interface compatibility and interface strength of fiber and resin and further increase protective performance of epoxy (EP) coating under the simulated deep-sea area and splash zone. After 168 h immersion under alternating hydrostatic pressure, CF@Ce-MI/EP coating displayed impressive impermeability and anti-corrosion performance, and the interfaces of fiber/epoxy adhered firmly. After the erosion wear test, the volume loss and mass loss of CF@Ce-MI/EP were decreased by 23.77% and 14.80%, respectively, compared with CF/EP. Finally, we discussed the protective mechanism of composite coating to reveal the different processes of interface failure caused by the high pressure and the impact of solid particles, respectively.

Bifunctional metal-organic frameworks as selective turn-on fluorescence sensors for tryptophan and heterogeneous catalysts for Knoevenagel condensation reaction

Two new doubly interpenetrated metal-organic frameworks (MOFs) with formulas [{Zn(L1)(5-nipa)}·DMA]α (1a) and [{Cd(L2)(5-nipa)(H2O)}]α (1b) have been discussed herein, where [L1 = N,N'-(oxybis(4,1-phenylene))diisonicotinamide; L2 = N,N'-(methylenebis(4,1-phenylene)) diisonicotinamide; 5-H2nipa = 5-nitroisophthalic acid; DMA = dimethylacetamide]. A single crystal X-ray analysis reveals that 1a exhibits a 2D-interpenetrated interwoven sheet and finally adapts a 3D framework structure with the help of π···π stacking interactions. Similarly, 1b displays a two-fold interpenetrated 2D sheet-like architecture and is finally adjusted to a 3D structure. Both 1a and 1b feature channels with a cross-section of 25.06 × 25.06 Å2 and 24.01 × 24.01 Å2, respectively, running along the b-axis. Topological analysis of 1a and 1b by ToposPro suggests a (4)-connected uninodal sql topology with point symbol {44.62}. Further, 1a and 1b were exploited as molecular sensors for several amino acids exposing different shapes and sizes and exhibiting selective turn-on fluorescence sensing towards biologically important D/L-tryptophan with the notable limit of detection values of 0.084/0.110 μM and 0.143/0.141 μM, respectively, in aqueous medium. In addition, 1a and 1b were also exploited as heterogeneous catalysts towards several assorted aldehydes having different electronic environments, including sterically demanding aldehydes, under mild reaction conditions and obtained up to 97% of the respective Knoevenagel condensation product. Importantly, sterically hindered aldehydes also worked well with the MOF catalysts 1a and 1b, but showed comparatively low conversion. It is important to mention that in both cases, these MOF materials are recyclable for up to five consecutive runs without displaying any substantial loss in their sensing or catalytic activities. Moreover, the present investigation cultivates a new vision to design novel luminescent MOFs that can be used as multifunctional materials for the turn-on sensing of small organic molecules as well as instigated as heterogeneous catalysts in diverse organic transformation reactions.

Bifunctional MOFs with robust mesoporous armors and superionic conduction

Metal-organic frameworks (MOFs) have raised extensive attention for ionic conduction; however, the inferior ionic conductivity and weak mechanical strength of semi-solid MOF electrolytes have limited their further development. Here, bifunctional MOFs (BF-MOFs) with a yolk-shell structure have been designed to realize superionic conduction and high mechanical stiffness. In the BF-MOFs, the mesoporous shells work as robust armors for suppressing dendrite growth, and simultaneously provide perfect pathways for rapid and uniform ionic transport; the large gaps between the mesoporous shells and the MOF cores can store more Li ions for superionic conduction. In addition, the MOF cores function as ionic rectifiers for uniform Li deposition. As a result, the electrolyte with BF-MOFs delivers a high ionic conductivity of 1.27 × 10-3 S cm−1 at 30 °C and a high Li+ transference number of 0.74. An ultralong life of 4500 cycles with capacity retention of 96.5% is obtained in LiFePO4//Li cells. Furthermore, LiNi0.8Co0.1Mn0.1O2//Li cells are also fabricated, displaying remarkable durability with capacity retention of 92.2% after 800 cycles.

Creating Dual Active Sites in Conductive Metal‐Organic Frameworks for Efficient Water Splitting

AbstractThe achievement of bifunctional metal‐organic frameworks (MOFs) remains a huge challenge due to their lack of dual active sites. Herein, dual sites in the Co‐catecholate (Co‐CAT) are created through Ru, Ir, or Rh doping for overall water splitting. Among them, RuCo‐CAT exhibits excellent bifunctional activities, outperforming benchmarked Pt/C for the hydrogen evolution reaction (HER) and RuO2 for the oxygen evolution reaction (OER). The theoretical calculations demonstrate that the doped Ru atoms with optimal absorption energy for the hydrogen intermediate and the Co centers with a reduced energy barrier for the rate‐determining step are the active sites for HER and OER, respectively. Furthermore, the incorporation of Ru atoms can improve the electrical conductivity and capacity of water adsorption of Co‐CAT greatly, synergistically improving the bifunctional activity. This strategy for engineering dual active sites offers novel insights into designing bifunctional MOFs for overall water splitting.

On the role of graphene oxide in bifunctional Ni/MOF/rGO composites in electrochemical nitrate detection and oxygen evolution reaction

Bi-functional metal organic frameworks as promising porous framework hybrid materials for electrochemical nitrate sensing and oxygen evolution reaction.

Metal-organic framework (MOF) hybridized gold nanoparticles as a bifunctional nanozyme for glucose sensing.

Inspired by natural enzymes that possess multiple catalytic activities, here we develop a bifunctional metal-organic frame-work (MOF) for biosensing applications. Ultrasmall gold nano-particles (AuNPs) are grown in the internal cavities of an iron (Fe) porphyrin-based MOF to produce a hybridized nanozyme, AuNPs@PCN-224(Fe), in which AuNPs and PCN-224(Fe) exhibit the catalytic activity of glucose oxidase (GOx) and horseradish peroxidase (HRP), respectively. We established that the bifunctional nanozyme was capable of a cascade reaction to generate hydrogen peroxide in the presence of d-glucose and oxygen in situ, and subsequently activate a colorimetric or chemiluminescent substrate through HRP-mimicking catalytic activity. The nanozyme was selective over a range of other saccharides, and 93% of the catalytic activity was retained after being recycled five times.

Efficient As(V) and Hg(Ⅱ) removal from acidic wastewater by a sulphydryl functionalized UIO-66-NH2

Metal-organic frameworks (MOFs) have a high potential for removing heavy metal ions from wastewater. However, they could not remove opposite-charged metal species simultaneously by adsorption. In this study, a novel bifunctional MOF UIO-66-NH2(-SH) containing -NH2 and -SH functional groups (UIO-66-NH2(-SH), named Zr-DMBM) was fabricated by the ligand exchange method to serve as an adsorbent of electrostatically opposite As(V) and Hg(II). The structure-dependent adsorption of Zr-DMBM was optimised as Zr4+: BDC-NH2:-SH = 1:2:1 for As(V) and Hg(II). The removal rates of As(V) and Hg(II) were greater than 80 % over a wide pH range (pH = 1–9), with maximum adsorption capacities of 72.2 and 812.5 mg·g-1, respectively. For practical applications, microextraction column packing of Zr-DMBM was applied to efficiently and simultaneously remove As(V) and Hg(II) from wastewater. After As(V) and Hg(II) adsorption, the prepared column was easily regenerated using thiourea (0.1 M) and hydrochloric acid (0.1 M), and could be recycled five times without an evident reduction in adsorption capacity. The excellent performance of Zr-DMBM was attributed to the incorporation of -SH and –NH2 groups and its unique physicochemical properties. Moreover, X-ray diffraction (XRD) and scanning electron microscopy (SEM) indicated that Zr-DMBM exhibited the same topological structure as UIO-66-NH2, and Fourier transform infrared spectroscopy (FTIR) confirmed the presence of -SH groups in its structure. The adsorption kinetics further demonstrated the strong electrostatic attraction between Zr-DMBM and As(V) and Hg(II). Therefore, the combination of MOFs with microextraction column technology is a promising candidate for the simultaneous removal of As(V) and Hg(II) ions from wastewater. Moreover, the sulfhydryl-functionalised UIO-66-NH2 is suitable for industrial wastewater treatment owing to its excellent performance in a broad range of pH environments.

In-situ synthesis of [Ni(tzba)0.5(F)(bpy)] membrane with high H2 permeability through ultramicropores and selective CO2 adsorption with strong affinity of uncoordinated N-Ni-F− active sites

To simultaneously purify H2 and capture CO2 in the steam methane reforming (SMR) process for H2 production, a bifunctional metal organic framework (MOF) membrane ([Ni(tzba)0.5(F)(bpy)]) was proposed via an in-situ synthesis method to efficiently permeate H2 through ultramicropores and selectively adsorb CO2 with the strong affinity of uncoordinated N-Ni-F− active sites. Ni(tzba)0.5(F)(bpy) exhibited a good CO2 uptake capacity (4.3 mmol/g at 273 K and 110 kPa) because the F− anionic and exposed uncoordinated tetrazolate N atoms in ligands have an excellent affinity to CO2. Dynamic breakthrough experiments suggested that Ni(tzba)0.5(F)(bpy) achieved efficient separation of CO2 from H2, CH4, and N2. Ni(tzba)0.5(F)(bpy) MOF membrane also shows outstanding H2/CO2 separation performance because the high adsorption capacity of CO2 reduced CO2 mobility. The H2 permeability of 1.59 × 105 Barrer and H2/CO2 ideal selectivity of 14.43 greatly exceeded the latest upper bound. Continuous permeability tests of up to 100 h demonstrated the long-term stability of the Ni(tzba)0.5(F)(bpy) MOF membrane for H2 separation applications. Density functional theory (DFT) calculations clarified the adsorption mechanism of Ni(tzba)0.5(F)(bpy) towards gases.

Bifunctional metal-organic framework-derived nitrogen-doped porous multishell CuCoS@NiCoS nanospheres for supercapacitors and hydrogen evolution reactions

Transition metal sulfide porous multishell nanostructures with high active sites have great potential for application as bifunctional materials. Herein, bifunctional metal-organic framework (MOF)-derived nitrogen-doped porous multishell CuCoS@NiCoS (N–CCS@NCS) nanospheres are synthesized on Cu–Co–O substrates. The tightly connected nanocluster particles transformed by MOFs have more active sites and surface area. The ion transport efficiency between the shell layers is improved and the resistance to ion transport is further reduced. Moreover, the porous multishell structure provides a buffer space for the shock generated by multiple rapid embedding/de-embedding of OH− ions and offered a stable structure. Interestingly, the number of shell layers, thickness, spacing, and shell density of the N–CCS@NCS nanospheres can be controlled by adjusting the Ni content. Owing to its compositional and structural advantages, the N–CCS@NCS electrode exhibited a high specific capacitance of 1259 F g−1 at 0.5 A g−1. The assembly N–CCS@NCS//activated carbon asymmetrical supercapacitor exhibited specific energy of 87.3 W h kg−1 at 825 W kg−1 and a capacitance retention rate of 81.3 % after 8400 cycles. Furthermore, the N–CCS@NCS electrocatalyst exhibited outstanding hydrogen precipitation properties (254 mV at 10 mA cm−2) in 1 M KOH and excellent stability over 20 h. Therefore, MOF-derived porous multishell metal sulfides are promising candidates for supercapacitor and hydrogen evolution reaction dual applications.

Bifunctional metal–organic frameworks afforded by postsynthetic modification for efficient cycloaddition of CO2 and epoxides

AbstractBifunctional ionic metal–organic frameworks (MOFs) containing Lewis acid sites (unsaturated metal sites) and halide ions (Cl−, Br−, and I−) have attracted increasing attention due to their extra high activity for the cycloaddition of CO2 with epoxides. Herein, a novel microporous MOF (1‐Eu), namely, [Eu3(L)2(HCOO)(H2O)5]·14H2O (H4L = 2,6‐di(2,4‐dicarboxyphenyl)‐4‐(pyridine‐4‐yl)pyridine), has been synthesized by using a new bipyridyl‐based tetracarboxylate ligands (H4L). Structural analyses show that 1‐Eu is a 3D framework in which 1D chains with alternating triple and single carboxylate bridges are interlinked by the L ligands and contains microporous channels with uncoordinated pyridyl N atoms, which are easy to be modified by N‐methylation. Therefore, three bifunctional N‐methylation 1‐Eu MOFs, 1‐Eu‐MeX (X = Cl−, Br−, and I−), were successfully prepared from the 1‐Eu MOF by a postsynthetic modification (PSM) method. 1‐Eu‐MeX can efficiently catalyze the cycloaddition reaction without any cocatalyst and solvent. Among them, the 1‐Eu‐MeI catalyst displays the highest catalytic performance. Our work thus represents a rare demonstration of ionic MOFs as heterogeneous catalysts for efficient CO2 fixation with epoxides. More significantly, 1‐Eu‐MeX are the first reported Eu‐based ionic MOFs with the bipyridyl‐based tetracarboxylate ligand.

Bifunctional Metal-Organic Framework Functionalized by Dimethylamine Cations: Proton Conduction and Iodine Vapor Adsorption.

A metal-organic framework, {Zn3(BTB)2(μ3-OH)[(CH3)2NH2](H2O)}n (1), was synthesized based on H3BTB (1,3,5-tri(4-carboxyphenyl)benzene). An AC impedance test proves that 1 has a relatively high conductivity performance of 1.52 × 10-3 S·cm-1 at 338 K and 98% RH. The proton conductivity of the composite film 1@CS-9 (CS = chitosan) reaches 1.84 × 10-1 S·cm-1 at 328 K and 98% RH. In addition, 1 is discovered to have a good adsorption effect on iodine vapor, and the adsorption capacity reaches 726 mg·g-1. The multifunctionality caused by dimethylamine cations was investigated for the first time, which has implications for multifunctionality generated by host-guest molecules.

Facile Synthesis of Bifunctional Metal–Organic Framework Nanoparticles for Isolation of Extracellular Vesicles

Facile Synthesis of Bifunctional Metal–Organic Framework Nanoparticles for Isolation of Extracellular Vesicles

Constructing bifunctional metal–organic framework based nanozymes with fluorescence and oxidase activity for the dual-channel detection of butyrylcholinesterase

Herein, we reported a novel strategy for the fabrication of bifunctional metal–organic framework based nanozymes (oxidized UiO-66-NH2@Ce), which displayed excellent oxidase mimic activity as well as fluorescence property. The bifunctional oxidized UiO-66-NH2@Ce possess excellent oxidase activity due to oxidase-like active Ce4+/Ce3+ sites, which makes the nanozymes have strong positive charge, resulting in a stronger affinity for the negatively charged chromogenic substrate 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS). Utilizing the bifunctional oxidized UiO-66-NH2@Ce, a sensitive fluorometric and colorimetric dual-channel detection strategy for butyrylcholinesterase (BChE) was fabricated for the first time. The oxidized UiO-66-NH2@Ce could catalyze the oxidation of colorless ABTS to green oxABTS, which in turn quench the fluorescence of oxidized UiO-66-NH2@Ce. Butyrylcholinesterase (BChE) can catalyze the hydrolysis of S-butyrylthiocholine iodide (BTCh) to produce thiocholine, which could prevent the oxidation of ABTS, resulting in the fluorescence of oxidized UiO-66-NH2@Ce recovered. Both the colorimetric and fluorometric dual-channel sensing platform displayed a sensitive response to BChE, and the limits of detection (LOD) for BChE could achieve as low as 0.056 and 0.050U/L, respectively. The dual-output assay for BChE detection displayed excellent application prospects.

Nitrogen-rich dual linker MOF catalyst for room temperature fixation of CO2 via cyclic carbonate synthesis: DFT assisted mechanistic study

The benign synthesis of a novel Zn based Lewis acid-base bifunctional metal-organic framework (ITH-1) and its room temperature catalytic ability for the chemical fixation of carbon dioxide via cyclic carbonate synthesis is reported herein. ITH-1 is characterized by the presence of mono coordinated pendant imidazole groups throughout the framework inducing Lewis basicity. The synthesized material is crystallized in the monoclinic space group as revealed by the Single Crystal X-ray Diffraction Analysis and possesses a 2 D non-planar interdigitated network wherein the neighbouring sheets are connected via strong hydrogen bonding (1.947 Å). ITH-1 was characterized thoroughly via various physicochemical analyses such as XRD, FT-IR, Raman, FE-SEM, CHN, ICP, TGA and was found thermally stable up to 300 ⁰C. The co-existence of accessible and active Lewis acid (Zn) –Lewis base (imidazole) moieties rendered ITH-1 the potential to catalyse the cycloaddition of CO2 with propylene oxide under solvent and co-catalyst free conditions (~95% conversion) at moderate temperatures with remarkable reusable performance (over 5 times). ITH-1 manifested excellent CO2 conversion even under room temperature and 1 bar pressure in the presence of a co-catalyst. Density Functional Theory (DFT) calculations utilizing M06 functional were exercised to envisage the mechanism behind the successful CO2 conversion by ITH-1 at room temperature and were found to be in clear agreement with the experimental results.