A Catalytically Accessible Polyoxometalate in a Porous Fiber for Degradation of a Mustard Gas Simulant

Reactive Polymers of Intrinsic Microporous Aerogels for Rapid Mustard Gas Detoxification

Polymers of intrinsic microporosity (PIMs) have broad application prospects in the detoxification of chemical warfare agents (CWAs) due to their unique pore structure, good tunable reactivity, and solution processability. However, its pore structure is relatively homogeneous, resulting in high resistance to mass transfer. Here, inspired by fractal structure in nature, a structure engineering strategy is proposed to develop 3D reactive nanofibrous aerogels featuring hierarchical porous structures to minimize mass transfer resistance. These aerogels are fabricated with amidoxime-modified PIM-1 (AO-PIM-1) nanofibers serving as building units and flexible SiO2 nanofibers acting as reinforcement. The macro/mesopores of amidoxime-modified PIM-1 nanofibrous aerogels (APAs) originating from freeze-shaping and electrospinning provide interconnected channels for the diffusion of CWAs, and the intrinsic micropores of AO-PIM-1 can effectively trap and anchor adsorbate molecules. In addition, the reactivity of the APAs can be activated by chlorine bleaching. This process forms an N-chlorine structure, which effectively oxidizes the adsorbed CWAs simulant 2-chloroethyl ethyl sulfide (CEES) by APAs, converting them into non-toxic products. The resulting aerogels have the properties of ultralight weight (8 mg cm-3), reversible compression strain of 60%, and repeatable sulfur mustard decontamination (half-life of 1.27 min). These characteristics indicate significant potential for the use in protective materials against vesicant CWAs.

Ultra-Fast Degradation of Mustard Gas Simulant by Titanium Dioxide-Phosphomolybdic Acid Sub-1 nm Nanobelts

The development of novel catalysts for the rapid detoxification of sulfur mustard holds paramount importance in the field of military defense. In this work, titanium dioxide-phosphomolybdic acid sub-1 nm nanobelts (TiO2/PMA SNBs) are employed as effective catalysts for the ultra-fast degradation of mustard gas simulants (2-chloroethyl ethyl sulfide, CEES) with 100% selectivity and a half-life (t1/2, time required for 50% conversion) as short as 12 s, which is the fastest time to the best of the knowledge. Even in dark conditions, this material can still achieve over 90% conversion within 5 min. A mechanism study reveals that the rapid generation rate of 1O2 and O2 •- in the presence of TiO2/PMA SNBs and H2O2 plays a crucial role in facilitating the efficient oxidation of CEES. A filter layer of a gas mask loaded with TiO2/PMA SNBs and H2O2/polyvinylpyrrolidone cross-linked complex (PHP) is constructed, which demonstrates remarkable stability and exhibits exceptional efficacy in the detoxification of CEES in the presence of a small amount of water. This innovation offers great potential for enhancing personal protective equipment in practical applications.

Measuring Mass Transfer of n-Hexane and 2-Chloroethyl Ethyl Sulfide in Sorbent/Polymer Fiber Composites Using a Volumetric Adsorption Apparatus

The integration of metal-organic frameworks (MOFs) into composite systems serves as an effective strategy to increase the processability of these materials. Notably, MOF/fiber composites have shown much promise as protective equipment for the capture and remediation of chemical warfare agents. However, the practical application of these composites requires an understanding of their mass transport properties, as both mass transfer resistance at the surface and diffusion within the materials can impact the efficacy of these materials. In this work, we synthesized composite fibers of MOF-808 and amidoxime-functionalized polymers of intrinsic microporosity (PIM-1-AX) and measured the adsorption and mass transport behavior of n-hexane and 2-chloroethyl ethyl sulfide (CEES), a sulfur mustard simulant. We developed a new Fickian diffusion model for cylindrical shapes to fit the dynamic adsorption data obtained from a commercial volumetric adsorption apparatus and found that mass transport behavior in composite fibers closely resembled that in the pure PIM fibers, regardless of MOF loading. Moreover, we found that n-hexane adsorption mirrors that of CEES, indicating that it could be used as a structural mimic for future adsorption studies of the sulfur mustard simulant. These preliminary insights and the new model introduced in this work lay the groundwork for the design of next-generation composite materials for practical applications.

Role of Metal-Organic Framework Topology on Thermodynamics of Polyoxometalate Encapsulation

Polyoxometalates (POMs) are discrete anionic clusters whose rich redox properties, strong Bro̷nsted acidity, and high availability of active sites make them potent catalysts for oxidation reactions. Metal-organic frameworks (MOFs) have emerged as tunable, porous platforms to immobilize POMs, thus increasing their solution stability and catalytic activity. While POM@MOF composite materials have been widely used for a variety of applications, little is known about the thermodynamics of the encapsulation process. Here, we utilize an up-and-coming technique in the field of heterogeneous materials, isothermal titration calorimetry (ITC), to obtain full thermodynamic profiles (ΔH, ΔS, ΔG, and Ka) of POM binding. Six different 8-connected hexanuclear Zr-MOFs were investigated to determine the impact of MOF topology (csq, scu, and the) on POM encapsulation thermodynamics.

Linker Independent Regioselective Protonation Triggered Detoxification of Sulfur Mustards with Smart Porous Organic Photopolymer

The development of efficient metal-free photocatalysts for the generation of reactive oxygen species (ROS) for sulfur mustard (HD) decontamination can play a vital role against the stockpiling of chemical warfare agents (CWAs). Herein, one novel concept is conceived by smartly choosing a specific ionic monomer and a donor tritopic aldehyde, which can trigger linker-independent regioselective protonation/deprotonation in the polymeric backbone. In this context, the newly developed vinylene-linked ionic polymers (TPA/TPD-Ionic) are further explored for visible-light-assisted detoxification of HD simulants. Time-resolved-photoluminescence (TRPL) study reveals the protonation effect in the polymeric backbone by significantly enhancing the life span of photoexcited electrons. In terms of catalytic performance, TPA-Ionic outperformed TPD-Ionic because of its enhanced excitons formation and charge carrier abilities caused by the donor-acceptor (D-A) backbone and protonation effects. Moreover, the formation of singlet oxygen (1 O2 ) species is confirmed via in-situ Electron Spin Resonance (ESR) spectroscopy and density functional theory (DFT) analysis, which explained the crucial role of solvents in the reaction medium to regulate the (1 O2 ) formation. This study creates a new avenue for developing novel porous photocatalysts and highlights the crucial roles of sacrificial electron donors and solvents in the reaction medium to establish the structure-activity relationship.

Electrospun green-emitting La2O2CO3:Tb3+ nanofibers and La2O2CO3:Tb3+/Eu3+ nanofibers with white-light emission and color-tuned photoluminescence

Color-tuned luminescence and white-light emission materials have attracted much attention owing to their broad application prospects. Generally, Tb³⁺ and Eu³⁺ co-doped phosphors have color-tuned luminescence, but white-light emission is rarely achieved. In this work, color-tunable photoluminescence and white light emission are achieved in Tb³⁺ and Tb³⁺/Eu³⁺ doped monoclinic-phase La₂O₂CO₃ one-dimensional (1D) nanofibers synthesized by electrospinning united with succedent strictly controlling calcination procedure. The prepared samples own excellent fibrous morphology. La₂O₂CO₃:Tb³⁺ nanofibers are the superior green-emitting phosphors. To obtain 1D nanomaterials with color-tunable fluorescence, particularly those with white-light emission, Eu³⁺ ions are further selected and doped into La₂O₂CO₃:Tb³⁺ nanofibers to obtain La₂O₂CO₃:Tb³⁺/Eu³⁺ 1D nanofibers. The major emission peaks of La₂O₂CO₃:Tb³⁺/Eu³⁺ nanofibers at 487, 543, 596 and 616 nm are attributed to ⁵D₄→⁷F₆ (Tb³⁺), ⁵D₄→⁷F₅ (Tb³⁺), ⁵D₀→⁷F₁ (Eu³⁺) and ⁵D₀→⁷F₂ (Eu³⁺) energy levels transitions under 250-nm (for Tb³⁺ doping) and 274-nm (for Eu³⁺ doping) UV light excitation, respectively. At different wavelengths excitation, La₂O₂CO₃:Tb³⁺/Eu³⁺ nanofibers with excellent stability achieve color-tuned fluorescence and white-light emission with the help of energy transfer from Tb³⁺ to Eu³⁺ and tuning the doping concentration of Eu³⁺ ions. Formative mechanism and fabrication technique of La₂O₂CO₃:Tb³⁺/Eu³⁺ nanofibers are advanced. The design concept and manufacturing technique developed in this work may offer fresh insights for synthesizing other 1D nanofibers doped with rare earth ions to tune emitting fluorescent colors.