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Diethyl cyanophosphonate (DCNP), a simulant of Tabun, is a common pollutant in pharmaceutical waste and poses a high risk to living organisms. Herein, we demonstrate a compartmental ligand-derived trinuclear zinc(II) cluster [Zn3(LH)2(CH3COO)2] as a probe for the selective detection and degradation of DCNP. It consists of two pentacoordinated Zn(II) [4.4.3.01,5]tridecane cages bridged through a hexacoordinated Zn(II) acetate unit. The structure of the cluster has been elucidated by spectrometric, spectroscopic, and single-crystal X-ray diffraction studies. The cluster shows a two-fold increased emission as compared to the compartmental ligand (at λexc = 370 nm and λem = 463 nm) due to the chelation-enhanced fluorescence effect and acts as a turn-off signal in the presence of DCNP. It can detect DCNP at nano levels up to 186 nM (LOD). The direct bond formation between DCNP and Zn(II) via the –CN group degrades it to inorganic phosphates. The mechanism of the interaction and degradation is supported by spectrofluorimetric experiments, NMR titration (1H and 31P), time of flight mass spectrometry and density functional theory calculations. The applicability of the probe has been further tested by the bio-imaging of zebrafish larvae, analysis of high-protein food products (meat and fish) and vapour phase detection by paper strips. [ABSTRACT FROM AUTHOR]

This paper presents a process for synthesising iron oxide nanoparticles modified with Cr(II), Cr(III) and Mn(II) ions and immobilised peroxidase. The obtained bionanocatalyst can be successfully applied to biocatalytic hydrogen peroxide decomposition reactions in pollutant removal processes. The iron oxide nanoparticles formed by Fe3O4 with Fe2O3 displayed sizes below 10 nm. The sorption capacities of the material for Cr(II), Cr(III) and Mn(II) ions were 8.81, 5.30, and 5.01 mg g−1, respectively. In the second step, after adsorption of the ions, the materials were subjected to peroxidase immobilisation processes, yielding biocatalysts with hydrogen peroxide degradation activities of, respectively 1.5, 2.1 and 1.4 units per mg. For H2O2 degradation, values of 27.9, 14.8, 20.4 and 0. 2 μg H2O2 per unit POX were achieved for Cr(II)/Fe3O4/Fe2O3/POX, Cr(III)/Fe3O4/Fe2O3/POX, Mn(II)/Fe3O4/Fe2O3/POX and pure peroxidase (POX), respectively, confirming the catalytic efficiency of the carrier-embedded enzyme, demonstrating that the developed method enhances the peroxidase efficiency. [ABSTRACT FROM AUTHOR]

Given the enormous safety risks and environmental pollution that restrict the green development of isocyanate produced by phosgene reactions, we propose a new green and intrinsically safe route for synthesizing diisocyanates containing the furan ring from 5-hydroxymethylfurfural. In this work, the following novel reactions have been systematically investigated, including synthesizing a new compound methyl furan-2,5-dimethylene dicarbamate (FDC) using 2,5-bis(aminomethyl)furan (BAF) and dimethyl carbonate (DMC), the selective hydrogenation of FDC to a new compound methyl tetrahydrofuran-2,5-dimethylene dicarbamate (THFDC), and FDC and THFDC catalytic decomposition to produce corresponding furan-2,5-dimethylene diisocyanate (FDI) and tetrahydrofuran-2,5-dimethylene diisocyanate (THFDI). The results showed that CH3ONa could effectively catalyze the synthesis of FDC from BAF and DMC, and the separation yield of FDC was 98.1% under mild conditions including a nBAF : nDMC ratio of 1 : 10 at 70 °C for 4 h. CH3ONa can be recycled up to four times with high stability. A 0.5% Pd/γ-Al2O3 catalyst with low Pd loading was prepared, and it showed high catalytic activity and stability for FDC hydrogenation to THFDC, with a THFDC yield of 99.9% at 100 °C, 2 MPa H2 and 1 h, and the catalyst could be reused after simple treatment with ethanol. The structure–activity relationship of supported Pd catalysts was studied. The conditions for the thermal decomposition reactions of FDC and THFDC were optimized, resulting in FDI and THFDI yields as high as 89.6% and 92.8%, respectively. Owing to the urgent need for raw materials sustainability and environmental friendliness, the brand-new safe pathway for synthesizing FDI and THFDI was constructed, significantly improving the competitiveness of the non-phosgene method in preparing bio-based isocyanate. [ABSTRACT FROM AUTHOR]

Asymmetric organocatalysis has been recognized as one of the "top 10 emerging technologies" in chemistry by IUPAC in 2019. Its potential to make chemical processes more sustainable is promising, but there are still challenges that need to be addressed. Developing new and reliable enantioselective processes for reproducing batch reactions on a large scale requires a combination of chemical and technical solutions. In this manuscript, we combine a robust immobilized chiral phosphoric acid with a new packed-bed reactor design. This combination allows scaling up of the enantioselective addition of thiols to imines from a few milligrams to a multi-decagram scale in a continuous flow process without physical or chemical degradation of the catalyst. [ABSTRACT FROM AUTHOR]

Anhydride-cured epoxy is a common insulating material used in electrical equipment, but recycling it effectively is difficult, which results in the overall abandonment of the equipment after decommissioning and serious environmental pollution. In order to make anhydride cured epoxy degradable while maintaining its electrical performance, we synthesized a high-performance epoxy insulating material that can be recycled and reused using triethanolamine as a transesterification catalyst co-accelerator. Results show that the new epoxy has the lowest dielectric loss of 0.0012, the highest breakdown strength of 42.26 kV mm−1, and the highest tensile strength of 93.7 MPa. The degradable epoxy can be recovered via mechanical hot pressing and regenerated through chemical degradation. Degradation products can be directly used as curing accelerators to complete the re-preparation of the insulating material. Even after recovery, the properties of the epoxy resin meet the application requirements of insulating materials. [ABSTRACT FROM AUTHOR]

Room-temperature sodium–sulfur (Na–S) batteries hold great potential for next-generation energy storage devices due to their high theoretical energy density and low cost. However, the shuttling effect of sodium polysulfide (Na2Sn) species and the sluggish kinetics of the electrochemical conversion reaction greatly hamper the practical application of Na–S batteries. To address these challenges, by means of density functional theory (DFT) computations, we proposed two-dimensional metal chloride (MCl2, M = Mg and Ni) monolayers as multifunctional anchoring materials, including immobilizing soluble Na2Sn intermediates, boosting the reduction reaction of Na2Sn and the decomposition of Na2S species. Our results revealed that the NiCl2 monolayer can effectively immobilize the higher-order Na2Sn species with a stronger binding strength than the common electrolytes to prevent their dissolution. In particular, the NiCl2 substrate exhibits excellent electrocatalytic activity for the sulfur reduction reaction with a low free energy barrier (0.37 eV) and the Na2S decomposition reaction with a small kinetic barrier (0.45 eV), greatly lowering the energy barriers of Na2Sn conversions during discharge and charge and thus guaranteeing the fast redox kinetics and high sulfur utilization of Na–S batteries. Therefore, we predicted that NiCl2 monolayers can be utilized as a highly efficient multifunctional anchoring material for Na–S batteries. [ABSTRACT FROM AUTHOR]

An efficient strategy for the chemical degradation of polyurethane materials to recover polymerizable polyols has long been sought as a means of achieving green chemistry and circular resource utilization. However, this remains a major challenge. The present investigation endeavors to address this conundrum by delving into the intricacies of the multi-stage degradation (MSD) mechanism and successfully executing a gradient deconstruction of PUFs at low temperatures with minimal energy consumption. This approach involves a preliminary deconstruction of PUFs via ammonolysis, followed by deep depolymerization through acidolysis. The resulting recycled polyols (RPs) have high reactivity and can be used as a partial substitute for virgin polyol (up to 30 wt%) without purification treatment in the production of flexible PUFs. Furthermore, the MSD approach exhibits good adaptability and can be employed for the recycling of other types of PUFs, with the obtained RP being capable of up to 25 wt% VP substitution in the synthesis of new PUFs. Our research represents a significant advance in the development of efficient chemical degradation technologies for PUFs, which can support the transition to green chemistry and resource circularity. It provides valuable theoretical support for the industrialization of PUF degradation and upcycling. [ABSTRACT FROM AUTHOR]

Hydrazine and its derivatives can be used to recover plutonium and uranium from spent nuclear fuel as well as to obtain UO2 or mixed-oxide fuels. Uranium hydrazinates xUO3·yN2H4·zH2O have been synthesized, and their structural peculiarities and phase transitions upon heating have been investigated. It has been found that the elemental composition of U(VI) hydrazinate can be described as UO3·0.3N2H4·1.7H2O. It is a poorly crystalline layered compound with a crystallite size of (14 ± 3) nm, structurally similar to schoepite and ammonium polyuranates with neutral N2H4 molecules between layers of U(VI)-oxygen pentagonal bipyramids. U(VI) is present in the form of a linear UO22+ cation. In an inert atmosphere above 90 °C, xUO3·yN2H4·zH2O decomposes, resulting in partial U(VI) reduction due to the high mobility of hydrazine in the interlayer space or insufficient ratio of N2H4 to U(VI). The weak exothermic effect of the decomposition reaction and absence of combustible gases make the thermal treatment of xUO3·yN2H4·zH2O secure and applicable for nuclear technology. [ABSTRACT FROM AUTHOR]

Catalytic decomposition of hydrazine nitrate is a very important research topic in the environmental protection field. Herein, we used an Ru/C catalyst for the decomposition of hydrazine nitrate in HNO3, and the reaction kinetics and mechanism were studied in detail. The kinetics study of the decomposition of hydrazine nitrate (0.01 M) was conducted in the temperature range 313–343 K in 0.1 M HNO3 in the presence of Ru/C. The apparent activation energy for this reaction was 46.6 kJ mol−1 according to a fitting of the experimental data, while the reaction order was 1.5. It was also found that the reaction pathway of the catalytic decomposition of hydrazine nitrate on the Ru/C catalyst involved two processes: heterogeneous catalytic disproportionation of hydrazine nitrate at the catalyst surface and oxidation of hydrazine nitrate with catalytically generated HNO2. [ABSTRACT FROM AUTHOR]

The reactivity of two different phosphate esters has been explored with calcium ions. The reaction of calcium oxide with a mixture of mono/bis 2-ethylhexyl phosphate and 1,10-phenanthroline leads to the formation of the 1-D polymer [(phen)Ca(ehpH)2]n (1). On the other hand, the reaction of Ca(OAc)2 with trimethyl phosphate in the presence of 1,10-phenanthroline however yields needle-shaped colourless crystals of [(phen)Ca(OAc)2]n (2). Compounds 1 and 2 have been characterized by various spectroscopic and analytical techniques. The solid-state structures have been determined by single crystal X-ray diffraction studies. The arrangement of rigid and flexible parts in 1 makes it an interesting compound to be studied for its thermal behaviour. DSC experiments performed above and below room temperature reveal thermal transitions in both the ranges, where below room temperature transition is prominent. A combination of variable temperature powder and single crystal X-ray diffraction experiments provides further insights into these transitions. Solid-state bulk thermolysis of 1 at 500 °C leads to an amorphous material contaminated with graphitic carbon which upon further heating to 600 °C produces crystalline α-Ca(PO3)2. [ABSTRACT FROM AUTHOR]

Gas generation-based immunoassay is considered an attractive biosensing platform for the detection of biomarkers by incorporating the target recognition event with a catalyzed gas-generating reaction. Herein, an optical gas pressure sensor based on a silver/polydimethylsiloxane (Ag/PDMS) bilayer system was designed as a signal transducer to read the concentration of the detection target alpha-fetoprotein (AFP) quantitatively. In this proposed pressure-based assay, silicon dioxide (SiO2) nanospheres decorated with platinum (Pt) nanoparticles were coupled to detect antibodies by covalent linkage, and the captured antibodies were conjugated with magnetic beads via streptavidin-biotin interaction, simultaneously. When the AFP was loaded, the Pt-catalyzed hydrogen peroxide (H2O2) decomposition reaction was triggered to induce a significant increase in the reflectance signal of the Ag/PDMS bilayer gas pressure sensor (BGPS) due to a "wrinkled–specular" transition of the Ag film's surface. Under optimal conditions, the pressure-based biosensor exhibited a broad linear detection range from 0.05 to 132 ng mL−1 with a limit of detection (LOD) of 0.016 ng mL−1 for AFP, which satisfies the requirements for the clinical detection of AFP. Besides, the high specificity and detection accuracy of our Ag/PDMS BGPS also proved its feasibility for practical diagnosis. [ABSTRACT FROM AUTHOR]

Monodisperse-porous Mn5O8 microspheres with multiple oxidation states were used as an efficient heterogeneous catalyst for the fast degradation of organic pollutants via peroxymonosulfate (PMS) activation. The presence of Mn(II), Mn(III), and Mn(IV) phases on the surface of the microspheres was shown by X-ray photoelectron spectroscopy. For the degradation studies, methylene blue (MB) and tetracycline (TC) were selected as the model organic pollutants. The removal process included both adsorption and chemical degradation stages for both pollutants. By using the Mn5O8–PMS system, complete removal of MB was achieved and 70% of TC was removed in a degradation period of 5 min. The high surface area originating from the porous nature and the crystalline phase found in the microspheres should provide very short removal periods with the selected pollutants. No significant change was observed in the removal behavior in the pH range of 3.3–9.0. The highest first order-rate constants were obtained as 0.961 min−1 and 0.570 min−1 for MB and TC, respectively. These values were approximately up to 24-fold higher with respect to similar degradation systems. The degradation runs performed using radical scavengers with the Mn5O8–PMS system demonstrated the presence of superoxide anion (O2*−) and singlet oxygen (1O2) radicals. The degradation efficiency decreased to 99.3% with MB and 89.3% with TC over five consecutive degradation runs. Final Mn concentrations lower than 0.14 ppm obtained at the end of the degradation runs demonstrated that monodisperse-porous Mn5O8 microspheres were a highly stable oxidation catalyst for the fast degradation of organic pollutants in an aqueous medium. [ABSTRACT FROM AUTHOR]

All-nitrogen solids, if successfully synthesized, are ideal high-energy-density materials because they store a great amount of energy and produce only harmless N2 gas upon decomposition. Currently, the only method to obtain all-nitrogen solids is to apply high pressure to N2 crystals. However, products such as cg-N tend to decompose upon releasing the pressure. Compared to covalent solids, molecular crystals are more likely to remain stable during decompression because they can relax the strain by increasing the intermolecular distances. The challenge of such a route is to find a molecular crystal that can attain a favorable phase under elevated pressure. In this work, we show, by designing a novel N16 molecule (tripentazolylamine) and examining its crystal structures under a series of pressures, that the aromatic units and high molecular symmetry are the key factors to achieving an all-nitrogen molecular crystal. Density functional calculations and structural studies reveal that this new all-nitrogen molecular crystal exhibits a particularly slow enthalpy increase with pressure due to the highly efficient crystal packing of its highly symmetric molecules. Vibration mode calculations and molecular dynamics (MD) simulations show that N16 crystals are metastable at ambient pressure and could remain inactive up to 400 K. The initial reaction steps of the decomposition are calculated by following the pathway of the concerted excision of N2 from the N5 group as revealed by the MD simulations. [ABSTRACT FROM AUTHOR]

Trimethylaluminum is the most used aluminum precursor in atomic and molecular layer deposition (ALD/MLD). It provides high growth-per-cycle (GPC), is highly reactive and is relatively low cost. However, in the deposition of hybrid alucone films, TMA tends to infiltrate into the films requiring very long purge steps and thereby limiting the deposition rate (nm s−1) of the process. From our previous studies, we know that dimethylaluminum isopropoxide (DMAI) could be a potential candidate to substitute TMA in alucone depositions as it does not seem to infiltrate into the films. In this study, we perform a more detailed investigation of MLD of alucone on an atmospheric pressure spatial MLD system using DMAI as the aluminum precursor. The effect of deposition temperature and reactant purge times on the overall GPC has been investigated and a decreasing GPC with increasing deposition temperature and increasing EG purge time has been observed. Furthermore, the DMAI alucone films have been compared for their chemical environment and degradation with the films prepared using TMA and EG, showing striking similarities between the two. The results demonstrate that DMAI can be used as an alternative precursor to TMA for MLD of alucone films and this work can be used as a guide for designing efficient MLD processes in the future. [ABSTRACT FROM AUTHOR]

Polymeric carbon nitride (PCN) is an emerging metal-free photocatalyst with high stability but is plagued by low photocatalytic efficiency due to the rapid charge carrier recombination behavior. Herein, Bi-doped graphitic carbon nitride nanotubes (BCN nanotubes) with a porous structure have been facilely prepared by one-step thermal polymerization of mixtures of melamine, urea and bismuth nitrate pentahydrate under an Ar atmosphere. With unique structural advantages for charge carrier transfer, light harvesting, and large surface area, the as-prepared BCN nanotubes exhibit excellent photocatalytic activity for the degradation of Rhodamine (Rh) B with a 26.8-fold higher reaction rate than that of PCN under visible light irradiation. This work provides informative principles about the synthesis of PCN with controlled morphology and element doping simultaneously for the photocatalytic degradation of chemical pollutants. [ABSTRACT FROM AUTHOR]

This work reports on the thermochemistry and kinetics of methyl propanoate (MePr) initial pyrolysis using the high ab initio multi-level composite W1 method over the temperature range 400–2000 K. Pyrolysis of MePr was simulated using ten complex bond fission reactions (R1–R10) and seven simple bond fission pathways (R11–R17). Rate coefficients of MePr decomposition have been estimated using transition state theory (TST) combined with tunneling through a one-dimensional Eckart barrier (Eck). Statistical Rice–Ramsperger–Kassel–Marcus (RRKM) tight theory has been also used in a pressure range of 0.001–100 atm. Our estimated rate coefficients are in strong agreement with previous literature and strongly pressure-dependent especially at high temperatures. In addition, thermodynamic parameters for MePr and some species involved in its decomposition reactions have been computed and compared with previous literature. [ABSTRACT FROM AUTHOR]

Density functional theory (DFT) and a periodic slab model were used to study the geometric structure, electronic structure and dehydrogenation mechanism of ammonia adsorption on the MoN(0001) surface. The surface energy calculation results indicated that MoN(0001) terminated by N was the most stable surface. The NH3 molecule was preferably adsorbed at the top position through its lone pair electrons, while the most stable adsorption sites of NH2 and H were triple hcp sites, and NH and N were adsorbed at triple fcc sites. The results of transition state calculations showed that the decomposition reaction of ammonia mainly takes place through a step-by-step dehydrogenation mechanism of N2H4, and the compound desorption reaction of nitrogen was the rate limiting step of the whole reaction. The results of electronic structure calculations showed that the N2H4 molecule was adsorbed on the surface through the mixture of the 2Pz orbital of N and the 4dz2 orbital of Mo. With the progress of dehydrogenation, the charge transfer phenomenon became more and more obvious. It could be predicted that the charge transfer between the adsorbate and substrate played an important role in the catalytic process of accelerating the dehydrogenation of NH3. [ABSTRACT FROM AUTHOR]

Environmental pollutants cause harm to animals, humans, and ecosystems worldwide, and powerful approaches are urgently needed to address this challenge. Dye degradation photocatalysis is one of the most promising methods for the chemical breakdown of organic pollutants. The large specific surface area produced by nanotechnology significantly improves photocatalytic performance. In the wave of full-fledged research on photocatalytic nanoparticles, there is a higher demand for unique means of characterization, such as real-time growth diagnosis and precise phase modulation of the particles. The advantages of laser spectroscopy are its non-contact methodology, rapid response, and accurate directionality, and therefore, spectral characterization methods are becoming more suitable for the real-time diagnosis of photocatalysts. In this review, traditional and spectroscopic means of characterizing dye degradation photocatalytic nanoparticles were examined. In addition, laser spectroscopic characterization can be performed using PL, LCRS, LSPR, SERS, UTAS, and LIBS, which were introduced in this review. Notably, the regulation applicability of LSPR and SERS with noble metal-based nanoparticles and the real-time flexibility of UTAS and LIBS are advantages during the use of laser spectroscopy to examine nanocomposites of photocatalysis. Moreover, the future development of laser spectroscopy for photocatalytic nanoparticle characterization was discussed. [ABSTRACT FROM AUTHOR]