UiO-66-NH2 Fabrics: Role of Trifluoroacetic Acid as a Modulator on MOF Uniform Coating on Electrospun Nanofibers and Efficient Decontamination of Chemical Warfare Agent Simulants

Manganese Oxides with Different Morphologies In Situ Anchored onto Ti3C2Tx Nanosheets: Highly Effective Decontamination toward Sulfur Mustard Simulants

Manganese oxides with porous structure and abundant active sites show potential in degrading sulfur mustard (HD). However, there is an interface effect between the oily liquid HD and nano oxides, and the powder is prone to agglomeration, which leads to incomplete contact and limited degradation ability. Here, we demonstrate a simple hydrothermal method for preparing MnO2/Ti3C2 composites to address this problem. The influence of morphology and crystal structure on performance are examined. Herein, flower-like MnO2 is loaded onto the surface or interlayer of Ti3C2-MXene nanosheets during in situ formation, significantly expanding the specific surface area. It also provides abundant acid-base sites and oxygen vacancies for the degradation of simulants 2-chloro-ethyl-ethyl thioether (2-CEES) without external energy, resulting in a reaction half-life as fast as 12.5 min. The relationship between structure and performance is clearly elaborated through temperature-programmed desorption (TPD), X-ray photoelectron spectroscopy (XPS), and X-ray absorption fine structure (XAFS) analyses. Based on in situ attenuated total reflection-Fourier transform infrared (ATR-FTIR) analysis, gas chromatography-mass spectrometry (GC-MS) analysis, and density functional theory (DFT) calculation, the proposed degradation pathway of the 2-CEES molecule is a synergistic effect of hydrolysis, elimination, and oxidation. Furthermore, the products are nontoxic or low toxic. Metal oxide/MXene composites are first illustrated for their potential use in degrading sulfur mustard, suggesting new insights into these materials as novel decontamination for decomposing chemical warfare agents.

Fiber Integrated Metal-Organic Frameworks as Functional Components in Smart Textiles

Owing to high modularity and synthetic tunability, metal-organic frameworks (MOFs) on textiles are poised to contribute to the development of state-of-the-art wearable systems with multifunctional performance. While these composite materials have demonstrated promising functions in sensing, filtration, detoxification, and biomedicine, their applicability in multifunctional systems is only beginning to materialize. This review highlights the multifunctionality and versatility of MOF-integrated textile systems. It summarizes the operational goals of MOF@textile composites, encompassing sensing, filtration, detoxification, drug delivery, UV protection, and photocatalysis. Building upon these recent advances, this review concludes with an outlook on emerging opportunities for the diverse applications of MOF@textile systems in the realm of smart wearables.

Humidity Enhances the Solid-Phase Catalytic Ability of a Bulk MOF-808 Metal-Organic Gel toward a Chemical Warfare Agent Simulant

Zirconium-based metal-organic frameworks have emerged as promising materials for detoxifying chemical warfare agents (CWAs) due to their remarkable stability and porosity. However, their practical application is hindered by issues with their powder form and poor catalytic performance in solid-phase degradation. To address these challenges, herein, a granular MOF-808 metal-organic gel (G808) is prepared under optimized conditions for catalytic degradation of the simulant 2-chloroethyl ethyl sulfide (2-CEES), a sulfide blister agent, in a neat state under different humidity conditions. The detoxification performance of G808 toward 2-CEES is significantly enhanced as the content of water present increases. The half-life of 2-CEES decontaminated by G808 can be shortened to 816 s, surpassing those of many other benchmark materials. To confirm the mechanism of catalytic degradation, we used gas chromatography, gas chromatography-mass spectrometry, and theoretical calculations. The findings revealed that hydrolysis was the predominant route. Additionally, granular G808 was reusable and adaptable to high-moisture environments, making it an excellent protective material with practical potential.

Mn-MOF catalyzed multi-site atom transfer radical polymerization electrochemical sensing of miRNA-21

A green electrochemical biosensor was developed based on metal-organic framework (MOF)-catalyzed atom transfer radical polymerization (ATRP) for quantifying miRNA-21, used as the proof-of-concept analyte. Unlike conventional ATRP, Mn-PCN-222 (PCN, porous coordination network) could be used as an alternative for green catalyst to substitute traditional catalysts. First, poly (diallyldimethylammonium chloride) (PDDA) was fixed on the surface of the indium tin oxide (ITO) electrode, and then the Mn-PCN-222 was linked to ITO electrode via electrostatic binding with PDDA. Next, aminated ssDNA (NH₂-DNA) was used to modify the electrode further by amide reaction with Mn-PCN-222. Then, the recognition and hybridization of NH₂-DNA with miRNA-21 prompt the generation of DNA-RNA complexes, which further hybridize with Fc-DNA@β-CD-Br₁₅ and permit the initiator to be immobilized on the electrode surface. Accordingly, β-CD-Br₁₅ could initiate the polymerization of ferrocenylmethyl methacrylates (FcMMA) under the catalysis of MOF to complete the ATRP reaction. FcMMA presented a distinct electrochemical signal at ~ 0.33 V. Taking advantage of the unique multi-site properties of β-CD-Br₁₅ and the efficient catalytic reaction induced by Mn-PCN-222, ultrasensitive detection of miRNA-21 was achieved with a detection limit of 0.4 fM. The proposed electrochemical biosensor has been applied to the detection of miRNA-21 in serum samples. Therefore, the proposed strategy exhibited potential in early clinical biomedicine.

Self-Assembled MOF-on-MOF Nanofabrics for Synergistic Detoxification of Chemical Warfare Agent Simulants

The development of protective fabrics that are capable of capturing and detoxifying a wide range of lethal chemical warfare agents (CWAs) in an efficient way is of great importance for individual protection gears/clothing. In this work, unique metal-organic framework (MOF)-on-MOF nanofabrics were fabricated through facile self-assembly of UiO-66-NH₂ and MIL-101(Cr) crystals on electrospun polyacrylonitrile (PAN) nanofabrics and exhibited intriguing synergistic effects between the MOF composites on the detoxification of both nerve agent and blistering agent simulants. MIL-101(Cr), although not catalytic, facilitates the enrichment of CWA simulants from solution or air, thereby delivering a high concentration of reactants to catalytic UiO-66-NH₂ coated on its surface and providing an enlarged contact area for CWA simulants with the Zr₆ nodes and aminocarboxylate linkers compared to solid substrates. Consequently, the as-prepared MOF-on-MOF nanofabrics showed a fast hydrolysis rate (t_1/2 = 2.8 min) for dimethyl 4-nitrophenylphosphate (DMNP) in alkaline solutions and a high removal rate (90% within 4 h) of 2-(ethylthio)-chloroethane (CEES) under environmental conditions, considerably surpassing their single-MOF counterparts and the mixture of two MOF nanofabrics. This work demonstrates synergistic detoxification of CWA simulants using MOF-on-MOF composites for the first time and has the potential to be extended to other MOF/MOF pairs, which provides new ideas for the development of highly efficient toxic gas-protective materials.

Enhanced oxygen reduction upon Ag-Fe-doped polyacrylonitrile@UiO-66-NH2 nanofibers to improve power-generation performance of microbial fuel cells

Microbial fuel cells (MFCs) have great potential as a new energy technology that utilizes microorganisms to produce electrical energy by decomposing organic matter. A cathode catalyst is key to achieving an accelerated cathodic oxygen reduction reaction (ORR) in MFCs. We prepared a Zr-based metal organic-framework-derived silver-iron co-doped bimetallic material based on electrospun nanofibers by promoting the in situ growth of UiO-66-NH₂ on polyacrylonitrile (PAN) nanofibers and named it as CNFs-Ag/Fe-m:n doped catalyst (m:n were 0, 1:1, 1:2, 1:3, and 2:1, respectively). Experimental results combined with density functional theory (DFT) calculations reveal that a moderate amount of Fe doped in CNFs-Ag-1:1 reduces the Gibbs free energy in the last step of the ORR. This indicates that Fe doping improves the performance of the catalytic ORR, and MFCs equipped with CNFs-Ag/Fe-1:1 exhibit a maximum power density of 737. 45 mW m^-2, significantly higher than that obtained for MFCs using commercial Pt/C (457.99 mW m^-2).

Aramid nanofibers supported metal-organic framework aerogel for protection of chemical warfare agent

Protective fabrics containing Zr-Based Metal-Organic Frameworks (Zr-MOFs) show great potential in the detoxification of chemical warfare agents (CWAs). However, the current studies still face the challenges of complicated fabrication processes, limited MOF loading mass, and insufficient protection. Herein, we developed a lightweight, flexible and mechanical robust aerogel by in situ growth of UiO-66-NH₂ onto aramid nanofibers (ANFs) and assembly of UiO-66-NH₂ loaded ANFs (UiO-66-NH₂@ANFs) into 3D hierarchically porous architecture. The UiO-66-NH₂@ANF aerogels feature high MOF loading of 261 %, high surface area of 589.349 m² g^-1, open and interconnected cellular structure, which provide efficient transfer channels and promote catalytic degradation of CWAs. As a result, the UiO-66-NH₂@ANF aerogels demonstrate high 2-chloroethyl ethyl thioether (CEES) removal rate at 98.9 % and a short half-life of 8.15 min. Moreover, the aerogels present good mechanical stability (recovery rate of 93.3 % after 100 cycles under 30 % strain), low thermal conductivity (λ of 25.66 mW m^-1 K^-1), high flame resistance (LOI of 32 %) and good wearing comfortableness, indicating promising potential in multifunctional protection against CWAs.

Porphyrin-Moiety-Functionalized Metal-Organic Layers Exhibiting Catalytic Capabilities for Detoxifying Nerve Agent and Blister Agent Simulants

The development of very efficient bifunctional catalysts for the simultaneous detoxification of two kinds of the deadliest chemical warfare agents (CWAs), nerve agent and blister agent, is highly desirable. In this study, two porphyrin-based ligands [tetrakis(4-carboxyphenyl) porphyrin (TCPP) and protoporphyrin IX (PPIX)] are introduced into 2D Zr-1,3,5-tris(4-carboxyphenyl)benzene (BTB) metal-organic layers (MOLs), composed of six-connected Zr₆ nodes and the tritopic carboxylate ligand BTB, by a solvent-assisted ligand incorporation method. The loads of TCPP and PPIX are 6.4 and 10.9 wt %, respectively. The detoxification of simulants of the nerve agent and the blister agent was conducted to investigate the catalytic activity of porphyrin-moiety-functionalized MOLs. The reaction half-life of optimal TCPP-functionalized MOL catalyzing the hydrolysis of a nerve agent simulant is only 2.8 min, meanwhile, the half-life of the selective catalytic oxidation of a blister agent simulant is only 1.2 min under LED illumination. More importantly, such a degradation half-life is only about 4 min under natural sunlight (∼60 mW/cm²). To our knowledge, TCPP-functionalized MOL is by far the most efficient catalyst for blister agent simulant degradation under solar light. Therefore, 2D ultrathin MOLs on demand appear to be a promising and efficient material platform for the development of bifunctional catalysts for CWA protection.

MOF-Polymer Mixed Matrix Membranes as Chemical Protective Layers for Solid-Phase Detoxification of Toxic Organophosphates

Zirconium-based metal-organic frameworks (Zr-MOFs) have been demonstrated as potent catalysts for the hydrolytic detoxification of organophosphorus nerve agents and their simulants. However, the practical implementation of these Zr-MOFs is limited by the poor processability of their powdered form and the necessity of water media buffered by a volatile liquid base in the catalytic reaction. Herein, we demonstrate the efficient solid-state hydrolysis of a nerve agent simulant (dimethyl-4-nitrophenyl phosphate, DMNP) catalyzed by Zr-MOF-based mixed matrix membranes. The mixed matrix membranes were fabricated by incorporating MOF-808 into the blending matrix of poly(vinylidene fluoride) (PVDF), poly(vinylpyrrolidone) (PVP), and imidazole (Im), in which MOF-808 provides highly active catalytic sites, the hydrophilic PVP helps to retain water for promoting the hydrolytic reaction, and Im serves as a base for catalytic site regeneration. Impressively, the mixed matrix membranes displayed excellent catalytic performance for the solid-state hydrolysis of DMNP under high humidity, representing a significant step toward the practical application of Zr-MOFs in chemical protective layers against nerve agents.

Functionalized reactive polymers for the removal of chemical warfare agents: A review

Protection from and removal of chemical warfare agents (CWAs) from the environment remains a global goal. Activated charcoal, metal oxides, metal organic frameworks (MOFs), polyoxometalates (POMs) and reactive polymers have all been investigated for CWA removal. Composite polymeric materials are rapidly gaining traction as versatile building blocks for personal protective equipment (PPE) and catalytic devices. Polymers are inexpensive to produce and easily engineered into a wide range of materials including films, electro-spun fibers, mixed-matrix membranes/reactors, and other forms. When containing reactive side-chains, hydrolysis catalysts, and/or oxidative catalysts polymeric devices are primed for CWA decontamination. In this review, recent advances in reactive polymeric materials for CWA removal are summarized. To aid in comparing the effectiveness of the different solid catalysts, particular attention is paid to the stoichiometric ratio of reactive species to toxic substrate (CWA or CWA simulant).

Dual-Function Detoxifying Nanofabrics against Nerve Agent and Blistering Agent Simulants

The development of functional materials that can detoxify multiple chemical warfare agents (CWAs) at the same time is of great significance to cope with the uncertainty of CWA use in real-world situations. Although many catalysts capable of detoxifying CWAs have been reported, there is still a lack of effective means to integrate these catalytic-active materials on practical fibers/fabrics to achieve effective protection against coexistence of a variety of CWAs. In this work, by a combination of electrospinning and in situ solvothermal reaction, PAN@Zr(OH)₄@MOF-808 nanofiber membranes were prepared for detoxification of both nerve agent and blistering agent simulants dimethyl 4-nitrophenyl phosphate (DMNP) and 2-chloroethyl ethyl sulfide (CEES). Under the catalytic effect of the MOF-808 component, DMNP hydrolysis with a half-life as short as 1.19 min was achieved. Meanwhile, an 89.3% CEES removal rate was obtained within 12 h by adsorption and catalysis of MOF-808 and Zr(OH)₄ components at ambient conditions, respectively. PAN@Zr(OH)₄@MOF-808 nanofiber membranes also showed a superior blocking effect on CEES compared to bare PAN and PAN@Zr(OH)₄ nanofiber membranes. Simultaneous protection against DMNP and CEES showed effective inhibition of both simulants for at least 2 h. The preparation method also imparted intrinsically good interfacial adhesion between the components, contributing to the excellent recycling stability of PAN@Zr(OH)₄@MOF-808 nanofiber membranes. Therefore, the prepared composite nanofabrics have great application potential, which provides a new idea for the construction of broad-spectrum protective detoxification materials.

Tuning the Electrical Conductivity of a Flexible Fabric-Based Cu-HHTP Film through a Novel Redox Interaction between the Guest-Host System

Integration of metal-organic frameworks (MOFs) and flexible fabrics has been recently considered as a promising strategy applied in wearable electronic devices. We synthesized a flexible fabric-based Cu-HHTP film consisted of Cu²⁺ ions and 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP) via a self-sacrificial template method. The obtained Cu-HHTP film displays an outstanding nanostructured surface and uniformity. Iodine molecules are first introduced into the pores of Cu-HHTP to investigate the influence of guest molecules on electrical conductivity in a 2D guest-host system. After doping, the conductivity of the Cu-HHTP film shows an increased dependent on the doping time, and the maximum value is more than 30 times that of the original MOFs. The enhanced electrical conductivity results from an intriguing redox interaction occurred between the confined iodine molecules and the framework. The organic ligands are oxidized by iodine molecules, and generating new ions allows for subsequent participation in the regulation of the mixed valence bands of copper ions in MOFs, changing the ratio of Cu²⁺/Cu⁺, promoting the charge transport of the framework, and then synergistically enhancing the electronic conductivity. This study successfully prepared a flexible fabric-based conductive I₂@Cu-HHTP film and presented insights into revealing the behavior of iodine molecules after entering the Cu-HHTP pores, expanding the possibilities of Cu-HHTP used in flexible wearable electronics.

Ultrafast Degradation and High Adsorption Capability of a Sulfur Mustard Simulant under Ambient Conditions Using Granular UiO-66-NH2 Metal-Organic Gels

Zirconium-based metal-organic frameworks (Zr-MOFs) have been considered as prospective materials for the degradation of nerve chemical warfare agents (CWAs) but show poor catalytic performance toward blister agents. Moreover, the powder issues and the poor adsorption capability also remain as the major challenges for the application of Zr-MOFs in practical CWA detoxification. Herein, a series of defected granular UiO-66-NH2 metal-organic gels are synthesized via adjusting the amount of added concentrated hydrochloric acid for the decontamination of 2-chloroethyl ethyl sulfide (2-CEES), a sulfur mustard simulant. The half-life of 2-CEES decontaminated by defected granular UiO-66-NH2 metal-organic gels can be shortened to 7.6 min, which is the highest reported value for MOFs under ambient conditions. The mechanism of decontamination is that the amino group on the linkers in UiO-66-NH2 MOGs undergoes a substitution reaction with 2-CEES to yield 2-(2-(ethylthio)ethylamino)terephthalic acid, which is less toxic and fixed in the frameworks. The recycling test corroborates that the granular UiO-66-NH2 xerogels possess good stability and reusability. Static adsorption and desorption tests show that UiO-66-NH2 xerogels possess a high 2-CEES vapor adsorption capacity of 802 mg/g after exposure for 1 d and only 28 wt % desorption capacity after air exposure for 7 d. The dual function of ultrafast degradation and high adsorption capability provide a firm foundation for using UiO-66-NH2 xerogels as a future protection media.