A solvent-free solid catalyst for the selective and color-indicating ambient-air removal of sulfur mustard

Permeable Self-Association of Metal-Organic Framework 808/Ag-Based Fiber Membrane for Broad-Spectrum and Highly Efficient Degradation of Biological and Chemical War Agents

The threat posed by biological and chemical warfare agents (BCWA) to national security, the environment, and personal health underscores the need for innovative chemical protective clothing. To address the limitations of conventional activated carbon materials, which are prone to falling off and adsorption saturation, an efficient self-association approach was introduced. In this study, we proposed the immobilization of metal-organic framework (MOF) 808 and Ag nanoparticles onto a polypropylene (PP) fiber membrane using a rapid self-association method facilitated by chitosan (CS). The MOF 808/Ag-based (PP-CS/808-Ag) fiber membrane demonstrated exceptional degradation efficiency, achieving a remarkable rate of t1/2 within 2 h for the mustard simulant 2-chloroethyl ethyl sulfide (2-CEES) and a rate of t1/2 = 4.12 min for the G-series simulant dimethyl 4-nitrophenylphosphate (DMNP). A theoretical computational model was developed to determine the overall reaction mechanism, and it was verified that MOF 808 and Ag nanoparticles were mainly involved in the hydrolysis process against 2-CEES and DMNP. The PP-CS/808-Ag composite fiber film was prepared as the core layer, and the fracture strength, bending resistance, and moisture permeability were better than those specified by many countries for biochemical protective clothing, showing that it has a broad application prospect in developing a generation of broad-spectrum bioprotective clothing.

Halogen Tailoring of Platinum Electrocatalyst with High CO Tolerance for Methanol Oxidation Reaction

The catalytic activity of platinum for CO oxidation depends on the interaction of electron donation and back-donation at the platinum center. Here we demonstrate that the platinum bromine nanoparticles with electron-rich properties on bromine bonded with sp-C in graphdiyne (PtBr NPs/Br-GDY), which is formed by bromine ligand and constitutes an electrocatalyst with a high CO-resistant for methanol oxidation reaction (MOR). The catalyst showed peak mass activity for MOR as high as 10.4 A mgPt -1, which is 20.8 times higher than the 20 % Pt/C. The catalyst also showed robust long-term stability with slight current density decay after 100 hours at 35 mA cm-2. Structural characterization, experimental, and theoretical studies show that the electron donation from bromine makes the surface of platinum catalysts highly electron-rich, and can strengthen the adsorption of CO as well as enhance π back-donation of Pt to weaken the C-O bond to facilitate CO electrooxidation and enhance catalytic performance during MOR. The results highlight the importance of electron-rich structure among active sites in Pt-halogen catalysts and provide detailed insights into the new mechanism of CO electrooxidation to overcome CO poisoning at the Pt center on an orbital level.

Porphyrin Aluminum Metal-Organic Framework in Liquid Water, its Interaction with the Oxidized Organosulfur Compound Diethyl Sulfoxide, and its Sorption from Aqueous Solution

Oxidized organosulfur compounds and, in particular, sulfoxides are of interest as solvents in the semiconductor and pharmaceutical industry, environmental contaminants, and simulants in deactivation of chemical warfare agents. An experimental study is reported of the interaction of porphyrin aluminum metal-organic framework Al-MOF-TCPPH2 (Compound 2) with diethyl sulfoxide (DESO) in pure form and in aqueous solution. First, the suitability of Compound 2 as sorbent in aqueous solution was assessed; namely, its long-term stability (up to 15 days) in liquid water has been investigated at room temperature and under stirring. Here, a novel facile spectroscopic method has been used, a periodic micro-sampling of sorbent from suspension, followed by vacuum mini-filtration and an ex situ time-dependent attenuated total reflection Fourier transform infrared spectroscopy (ATR FT-IR) analysis. Next, the interaction of Compound 2 with pure liquid DESO under ambient conditions was investigated, which yields the stoichiometric adsorption complex (Al-MOF-TCPPH2)1(DESO)2 denoted Compound 3. In this adsorption complex, molecules of DESO interact with the OH group and carboxylate group of the sorbent. Then, the removal of DESO from Compound 3 was assessed, using facile treatment with warm water in the micro Soxhlet apparatus followed by the ATR FT-IR analysis. Finally, Compound 2 was tested in sorption of DESO from diluted aqueous solution. In the initial step, the sorption proceeds very quickly (in <1 min the concentration of DESO decreases by about 20%) followed by a much slower step. The maximum amount of adsorbed DESO corresponds to half of the amount adsorbed from pure DESO as found by the high-performance liquid chromatography-ultraviolet detection method. This adsorbed amount corresponds to 1 mol DESO adsorbate per mol of sorbent. Porphyrin aluminum metal-organic framework Compound 2 is promising for the removal of DESO from diluted aqueous solution, and it is of interest for the removal of similar oxidized organosulfur compounds.

Role of Multiple Vanadium Centers on Redox Buffering and Rates of Polyvanadomolybdate-Cu(II)-Catalyzed Aerobic Oxidations

A recent report established that the tetrabutylammonium (TBA) salt of hexavanadopolymolybdate TBA₄H₅[PMo₆V₆O₄₀] (PV₆Mo₆) serves as the redox buffer with Cu(II) as a co-catalyst for aerobic deodorization of thiols in acetonitrile. Here, we document the profound impact of vanadium atom number (x = 0-4 and 6) in TBA salts of PV_xMo_12-xO₄₀^(3+x)- (PVMo) on this multicomponent catalytic system. The PVMo cyclic voltammetric peaks from 0 to -2000 mV vs Fc/Fc⁺ under catalytic conditions (acetonitrile, ambient T) are assigned and clarify that the redox buffering capability of the PVMo/Cu catalytic system derives from the number of steps, the number of electrons transferred each step, and the potential ranges of each step. All PVMo are reduced by varying numbers of electrons, from 1 to 6, in different reaction conditions. Significantly, PVMo with x ≤ 3 not only has much lower activity than when x > 3 (for example, the turnover frequencies (TOF) of PV₃Mo₉ and PV₄Mo₈ are 8.9 and 48 s^-1, respectively) but also, unlike the latter, cannot maintain steady reduction states when the Mo atoms in these polyoxometalate (POMs) are also reduced. Stopped-flow kinetics measurements reveal that Mo atoms in Keggin PVMo exhibit much slower electron transfer rates than V atoms. There are two kinetic arguments: (a) In acetonitrile, the first formal potential of PMo₁₂ is more positive than that of PVMo₁₁ (-236 and -405 mV vs Fc/Fc⁺); however, the initial reduction rates are 1.06 × 10^-4 s^-1 and 0.036 s^-1 for PMo₁₂ and PVMo₁₁, respectively. (b) In aqueous sulfate buffer (pH = 2), a two-step kinetics is observed for PVMo₁₁ and PV₂Mo₁₀, where the first and second steps are assigned to reduction of the V and Mo centers, respectively. Since fast and reversible electron transfers are key for the redox buffering behavior, the slower electron transfer kinetics of Mo preclude these centers functioning in redox buffering that maintains the solution potential. We conclude that PVMo with more vanadium atoms allows the POM to undergo more and faster redox changes, which enables the POM to function as a redox buffer dictating far higher catalytic activity.

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).

Vapor phase catalytic photooxidation of sulfides to sulfoxides: application to the neutralization of sulfur mustard simulants

A visible-light photocatalytic approach was developped for the aerobic oxidation of sulfides into the corresponding sulfoxides, including sulfur mustard simulants. The heterogeneous catalytic system is selective, operates in the gas...

Materials for the Simultaneous Entrapment and Catalytic Aerobic Oxidative Removal of Sulfur Mustard Simulants

Materials that both sequester chemical warfare agents (CWAs) and then catalytically decontaminate the entrapped CWAs are highly sought. This article reports such a system for air-based catalytic removal of the sulfur mustard (HD) simulant, 2-chloroethyl ethyl sulfide (CEES). Hypercrosslinked polymers (HCPs) sequester CEES, and an HCP-embedded oxidation system comprising tribromide, nitrate, and acid (NO_xBr_xH⁺) simultaneously catalyzes the aerobic and selective, oxidative conversion of the entrapped CEES to the desired far less-toxic sulfoxide under ambient conditions (air and temperature). (NO_xBr_xH⁺) has been incorporated into three HCPs, a fluorobenzene HCP (HCP-F), a methylated HCP (HCP-M), and an HCP with acidic moieties (HCP-A). HCP-A acts as both an absorbing material and a catalytic component due to its acidic side chains. All three HCP/NO_xBr_xH⁺ systems work rapidly under these optimally mild conditions. No light or added oxidants are required. The HCP/NO_xBr_xH⁺ systems are recyclable.

Reduced polyoxomolybdate immobilized on reduced graphene oxide for rapid catalytic decontamination of a sulfur mustard simulant

Keggin-type polyoxometalates (POMs) were immobilized on poly(diallyldimethylammonium chloride) (PDDA) functionalized reduced graphene oxide (rGO) by a facile and broad-spectrum hydrothermal method. The prepared POMs@PDDA-rGO composites (POM = H3PMo12O40, H3PW12O40, H5PMo10V2O40) have been thoroughly characterized using a series of techniques. The three composites can catalyze the oxidative decontamination of a sulfur mustard simulant, 2-chloroethyl ethyl sulfide (CEES) in the order of PMo12@PDDA-rGO > PMo10V2@PDDA-rGO > PW12@PDDA-rGO. Notably, under ambient conditions PMo12@PDDA-rGO can convert 99% of CEES within 30 min in the presence of nearly stoichiometric aqueous H2O2 (3 wt%) and its catalytic activity is significantly higher than that of homogeneous H3PMo12O40. XPS spectral analysis and control experiments indicate that the Mo center of POM is reduced from +6 to +5 during the hydrothermal process, and the excellent catalytic performance is related to the reduction of Mo. Moreover, the PMo12@PDDA-rGO composite is stable during the decontamination process and it can be used for at least five cycles without loss of activity.