Multichanneled hierarchical porous nanocomposite CuO/carbonized butterfly wing and its excellent catalytic performance for thermal decomposition of ammonium perchlorate

To meet the requirement of generating more apparent specific heat release at lower temperatures for ammonium perchlorate (AP)-based composite solid propellants, the development of high-performance catalysts for improving the thermal decomposition properties of AP still remains essential and challenging. Herein, a novel catalyst, multichanneled hierarchical porous nanocomposite of CuO and carbonized butterfly wing (CuO/CBW), has been prepared through an in-situ reaction on original butterfly wing scales. Owing to the high active surface area and the good electrical and thermal conductivity, as well as the synergistic effect of CuO nanoparticles (20–25 nm) and CBW, CuO/CBW nanocomposite exhibits excellent catalytic activity for AP thermal decomposition in reducing the high-temperature decomposition temperature by 88.3°C, lowering the apparent activation energy from 190.0 to 103.1 kJ mol⁻¹ and increasing the heat release from 255 to 1841 J g⁻¹.     

Synthesis,Crystal Structure,and Properties of Energetic Copper(II) Complex based on 3,5‐Dinitrobenzoic Acid and 1,5‐Diaminotetrazole

Energetic copper(II) complexes based on 3,5‐dinitrobenzoic acid (HDNBA) and 1,5‐diaminotetrazole (DAT), Cu(DNBA)₂(H₂O)₂ ( 1 ) and Cu(DAT)₂(DNBA)₂ ( 2 ) were synthesized and characterized by elemental analysis, IR spectroscopy, single‐crystal and powder X‐ray diffraction. In both complexes, Cu^II was coordinated to a plane tetragon, by four oxygen atoms from two DNBA^– ions and two coordinated H₂O molecules for 1 , and by two oxygen atoms and two nitrogen atoms from different DNBA^– ions and DAT ligands for 2 . Differential scanning calorimetry (DSC) and thermogravimetry (TG) analyses were employed to measure the thermal decomposition processes and non‐isothermal kinetics parameters of the complexes. The thermal decomposition onset temperatures of 1 and 2 are 321 and 177 °C. The apparent activation energies of the first exothermic decomposition peaks of 1 and 2 are 247.2 and 185.2 kJ · mol^–1. Both 1 (35 J, > 360 N) and 2 (12.5 J, > 360 N) are less sensitive than RDX. The catalytic effects on the decomposition of ammonium perchlorate (AP) of 1 and 2 were studied by DSC. All results supported the potential applications of the energetic complexes as additives of solid rocket propellants.     

Pure CuCr2O4 nanoparticles: Synthesis,characterization and their morphological and size effects on the catalytic thermal decomposition of ammonium perchlorate

In the present paper a pure phase of the copper chromite spinel nanoparticles (CuCr₂O₄ SNPs) were synthesized via the sol–gel route using citric acid as a complexing agent. Then, the CuCr₂O₄ SNPs has been characterized by field emission scanning electron microscope (FE-SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). In the next step, with the addition of Cu–Cr–O nanoparticles (NPs), the effects of different parameters such as Cu–Cr–O particle size and the Cu/Cr molar ratios on the thermal behavior of Cu–Cr–O NPs + AP (ammonium perchlorate) mixtures were investigated. As such, the catalytic effect of the Cu–Cr–O NPs for thermal decomposition of AP was evaluated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). TGA/DSC results showed that the samples with different morphologies exhibited different catalytic activity in different stages of thermal decomposition of AP. Also, in the presence of Cu–Cr–O nanocatalysts, all of the exothermic peaks of AP shifted to a lower temperature, indicating the thermal decomposition of AP was enhanced. Moreover, the heat released (ΔH) in the presence of Cu–Cr–O nanocatalysts was increased to 1490 J g⁻¹.     

Enhanced Thermal Decomposition Properties and Catalytic Mechanism of Ammonium Perchlorate over CuO/MoS2 Composite

In this report, CuO/MoS₂ composites were successfully prepared by the hydrothermal method where nano‐sized CuO was uniformly distributed on the surface of hierarchical MoS₂ substrates (CuO/MoS₂ composites). Their physicochemical properties and catalytic performance in ammonium perchlorate (AP) decomposition were investigated and characterized by XRD, SEM, TEM, BET, XPS, TG/DSC and combustion measurement. The results showed that it could decrease AP decomposition temperature at high decomposition stage from 416.5 °C to 323.5 °C and increase the heat release from 378 J/g (pure AP) to 1340 J/g (AP with catalysts), which was better than pure CuO nanoparticles (345.5 °C and 1046 J/g). Meanwhile, it showed excellent performance in combustion reaction either in N₂ or air atmosphere. The results obtained by photocurrent spectra, photoluminescence spectra and time‐resolved fluorescence emission spectra indicated that loading CuO mediated the generation rate and combination rate of electrons and holes, thus tuning the catalytic performance on AP decomposition. This study proved that employing the supports that can synergistically interact with CuO is an efficient strategy to enhance the catalytic performance of CuO.     

Synthesis and catalytic performance of ferrocene‐based compounds as burning rate catalysts

To overcome migration problems of ferrocene‐based burning rate catalysts and to enhance burning rate of ammonium perchlorate (AP)‐based propellants, eleven ferrocene‐based compounds ( 1 – 11 ) were synthesized by the condensation reaction of ferrocenecarbonyl chloride with corresponding amines and alcohols. The synthesis of 1 – 11 was confirmed using ¹H NMR, Fourier transform infrared and UV–visible spectroscopy. Their electrochemical properties were analyzed using cyclic voltammetry. The compounds showed redox behavior due to the presence of ferrocene. Their catalytic behavior in the thermal decomposition of AP was investigated using thermogravimetry (TG) and differential TG (DTG). In the presence of 5 wt% 1 – 11 , the thermal decomposition temperature of AP was significantly decreased. TG and DTG analyses showed that 1 – 11 had a good catalytic effect in the thermal decomposition of AP. Anti‐migration studies showed that migration of 1 – 11 was slower than that of 2,2‐bis(ethylferrocenyl)propane (catocene) and ferrocene. The effect of the presence of polar elements like oxygen and nitrogen on anti‐migration behavior of small ferrocene‐based compounds was also investigated. Oxygen‐containing compounds showed better anti‐migration behavior than nitrogen‐containing compounds.     

Gold nanoparticles supported on three‐dimensional nitrogen‐doped graphene: an efficient catalyst for selective aerobic oxidation of hydrocarbons under mild conditions

The development of efficient and selective aerobic oxidation of alkylarenes to form more functional compounds by heterogeneously catalysed routes still presents a great challenge in the fine chemical industry and is a major research topic. In this work, gold nanoparticles supported on three‐dimensional nitrogen‐doped graphene‐based frameworks (Au NPs@3D‐(N)GFs) were successfully synthesized and found to have an impressive performance as bifunctional catalysts (nitrogen dopant as base and gold nanoparticles as active site) in the controlled oxidation of alkylarenes. The catalyst was found to be a simple bench top, stable, recyclable and selective catalytic system for the aerobic oxidation of various types of alkylarenes into their corresponding ketones at room temperature under environmentally friendly conditions with good yields and high selectivity. Copyright © 2015 John Wiley & Sons, Ltd.     

纳米NdCoO3催化高氯酸铵热分解的DSC/TG-MS研究

采用微乳液法制备了立方晶系的NdCoO3纳米晶.利用DSC/TG-MS研究了NdCoO3对AP热分解的催化作用.结果表明,在NdCoO3的催化作用下,AP的热分解反应峰值温度下降了113℃,表观分解反应热从655 J·g-1增加到1 363 J·g-1,分解的气相产物主要有NH3,H2O,O2,HCl,N2O,NO,NO2和Cl2.在金属氧化物表面吸附生成超氧化离子(O2-)和氧离子(O-,O2-),这是加速AP分解反应的主要原因.加入NdCoO3催化AP热分解,由于对氨的氧化深度不同而导致分解放热量的增加.     

Ferrocenyl Ionic Compounds Based on 5‐Ferrocenyl‐1H‐tetrazole. Synthesis,Characterization, Migration,and Catalytic Effects During Combustion

Ferrocenyl ionic compounds, consisting of the 5‐ferrocenyltetrazolate anion and a guanidinium or a 1‐alkyl‐3‐methylimidazolium cation, were synthesized and characterized by ¹H NMR, ¹³C NMR, and UV/Vis spectroscopy, as well as elementary analysis. The molecular structures of four compounds were additionally confirmed by single‐crystal X‐ray diffraction. Results of the TG and DSC analyses showed that some compounds display high thermal stability. Cyclic voltammetry investigations suggested that the compounds exhibit redox waves for the ferrocenyl groups and are considered as irreversible redox systems. Migration studies revealed that migration trends of the compounds are much lower than that of 2, 2‐bis(ethylferrocenyl)propane (Catocene), extensively used in composite solid propellants. Their catalytic performances for thermal decomposition of ammonium perchlorate (AP), 1, 3,5‐trinitro‐1, 3,5‐triazacyclohexane (RDX), and 1, 2,5, 7‐tetranitro‐1, 3,5, 7‐tetraazacyclooctane (HMX) were evaluated by DSC and/or TG techniques. Most of the compounds exhibit high catalytic efficiency in the thermal degradation of AP and RDX. Those of the guanidine‐containing compounds 1 – 3 are better, implying that nitrogen‐rich moieties are beneficial to enhancing released heats of some energetic materials. These guanidine salts could be used as ferrocene‐based burning rate catalyst candidates in composite solid propellants.     

Synthesis,Characterization and Migration of Ionic Polyferrocenyl Compounds of 5‐Ferrocenyl‐1H‐tetrazole and Their Effects During Combustion

Eighteen ionic polyferrocenyl compounds with 5‐ferrocenyl‐1H‐tetrazolate as anion and mono‐ and dinuclear ferrocenyl‐alkylammonium as cations were synthesized and characterized by ¹H NMR, ¹³C NMR, FT‐IR, and UV/Vis spectroscopy, and elemental analysis. Molecular structures of three compounds were further confirmed by single‐crystal X‐ray diffraction. Their thermal stability was evaluated by TG and DSC and found that they are of high thermal stability. The cyclic voltammetry analysis suggested that each of the compounds exhibits only an irreversible redox wave of the ferrocene units in the molecule. Both migration and volatility test results showed that, on comparison with those of Catocene, all tested compounds exhibit much more excellent anti‐migration ability and most of the tested compounds have lower volatility. Their effects on the thermal disintegration of ammonium perchlorate (AP), 1,3,5‐trinitro‐1,3,5‐triazacyclohexane (RDX), and 1,2,5,7‐tetranitro‐1,3,5,7‐tetraazacyclooctane (HMX) were measured by DSC. The results revealed that most of the compounds exhibit significant catalytic effects on the thermal degradation of AP and RDX. Particularly, most of the compounds containing one ferrocene unit in their cations show higher activity than that of Catocene. These compounds can be used as alternatives to Catocene in the composite solid propellants.     

Iridium‐Catalyst‐Based Autonomous Bubble‐Propelled Graphene Micromotors with Ultralow Catalyst Loading

A novel concept of an iridium‐based bubble‐propelled Janus‐particle‐type graphene micromotor with very high surface area and with very low catalyst loading is described. The low loading of Ir catalyst (0.54 at %) allows for fast motion of graphene microparticles with high surface area of 316.2 m² g^?1. The micromotor was prepared with a simple and scalable method by thermal exfoliation of iridium‐doped graphite oxide precursor composite in hydrogen atmosphere. Oxygen bubbles generated from the decomposition of hydrogen peroxide at the iridium catalytic sites provide robust propulsion thrust for the graphene micromotor. The high surface area and low iridium catalyst loading of the bubble‐propelled graphene motors offer great possibilities for dramatically enhanced cargo delivery.     

干燥方式对高氯酸铵/石墨烯复合材料的结构和热分解行为的影响

通过溶胶-凝胶法制备了石墨烯水凝胶, 并将其与高氯酸铵(AP)复合, 然后分别采用自然干燥、冷冻干燥和超临界CO₂干燥三种干燥方式制备了AP/石墨烯复合材料, 并通过扫描电镜(SEM)、元素分析、X射线衍射(XRD)、差示扫描量热仪(DSC)和热重-红外联用技术(TG-FTIR)研究了不同干燥方式对其结构和热分解行为的影响. 结果表明, 干燥方式对AP/石墨烯复合材料的形貌具有明显影响, 其中通过超临界CO₂干燥制备的AP/石墨烯复合材料基本能保持与石墨烯气凝胶相似的外观和多孔结构. 通过自然干燥、冷冻干燥和超临界CO₂干燥制备的AP/石墨烯复合材料中AP的质量分数分别为89.97%、92.41%和94.40%, 其中通过超临界CO₂干燥制备的复合材料中AP的粒径尺寸为69 nm. DSC测试结果表明, 石墨烯对AP的热分解过程具有明显的促进作用, 能使AP的低温分解过程大大减弱, 高温分解峰温明显降低. 三种干燥方式相比, 通过超临界CO₂干燥制备的AP/石墨烯复合材料中石墨烯的促进作用最明显. 与纯AP相比, 其高温分解峰温降低了83.7℃, 表观分解热提高到2110 J·g^-1. TG-FTIR分析结果表明, AP/石墨烯复合材料的热分解过程中, AP分解产生的氧化性产物与石墨烯发生了氧化反应, 生成了CO₂.     

Mono‐ and Dinuclear Ferrocenyl Ionic Compounds with Polycyano Anions. Characterization,Migration, and Catalytic Effects on Thermal Decomposition of Energetic Compounds

Neutral ferrocene‐based burning rate (BR) catalysts show strong migration trends and volatility during long‐time storage and curing of the composite solid propellants. To reduce these disadvantages thirty‐two ferrocenyl quaternary ammonium compounds, paired with polycyano anions, were synthesized and characterized by ¹H NMR, ¹³C NMR, and UV/Vis spectroscopy, as well as elemental analysis. Additionally, crystal structures of eight compounds were confirmed by single‐crystal X‐ray diffraction. TG and DSC analyses indicated that the compounds containing 1,1,2,3,3‐pentacyanopropenide anions show high thermal stability. Cyclic voltammetry studies suggested that they are quasi‐reversible or irreversible redox systems. Anti‐migration tests verified that the tested compounds show very low migration tendency and some of them exhibit no migration after 30 days aging at 70 °C. Their catalytic efficiency in the thermal decomposition of ammonium perchlorate (AP), 1,3,5‐trinitro‐1,3,5‐triazacyclohexane (RDX), and 1,2,5,7‐tetranitro‐1,3,5,7‐tetraazacyclooctane (HMX) were examined by DSC analyses. The results revealed that most of the compounds exhibit distinct effects on the thermal degradation of AP and RDX. Two compounds have good catalytic ability in the thermal decomposition of HMX, representing rare examples of the reported ferrocenyl ionic compounds, which display catalytic property during combustion of HMX.     

Preparation, characterization and catalytic property of CuO nano/microspheres via thermal decomposition of cathode-plasma generating Cu2(OH)3NO3 nano/microspheres

CuO nano/microspheres with a wide diametric distribution were prepared by thermal decomposition of Cu(2)(OH)(3)NO(3) nano/microspheres formed in a simple asymmetric-electrode based cathodic-plasma electrolysis. The morphological, componential, and structural information about the two kinds of spheres were characterized in detail by SEM, TEM, EDX, XPS and XRD, and the results revealed that the morphology of the spheres were well kept after the componential and structural transformation from Cu(2)(OH)(3)NO(3) into CuO. The TGA/DSC study showed that the CuO nano/microspheres could be explored to be a promising additive for accelerating the thermal decomposition of ammonium perchlorate (AP). Combining with the current curve and emission spectrum measured in the plasma electrolysis, formation mechanism of the Cu(2)(OH)(3)NO(3) spheres was also discussed.     

Syntheses of conductive adhesives based on epoxy resin and polyanilines by using N‐tert‐butyl‐5‐methylisoxazolium perchlorate as a thermally latent curing reagent

Conductive composites consisted of epoxy resin and polyanilines (PANIs) doped with dodecylbenzenesulfonic acid ( 1 ), dodecylsulfonic acid (2), di(2‐ethylhexyl)sulfosuccinic acid (3), and HCl were synthesized by use of N‐tert‐butyl‐5‐methylisoxazolium perchlorate (5) under various reaction conditions. It was found that the composites with PANI doped with acid 2 (PANI‐2) prepared by curing with 10 mol % of reagent 5 at 80 °C for 12 h showed high electroconductivity along with the low conducting percolation threshold (3 wt % of PANI‐2). Furthermore, the composite with even ?10 wt % of PANI‐2 exhibited ?10^?1 S/cm of electroconductivity. The UV–vis and IR measurements indicated that the conductive emeraldine salt form of PANI‐2 in the composite was maintained after the curing reaction. The thermal stability was studied by TGA and DSC measurements, and then, the T_d10 and T_g of the composite with 5 and 10 wt % of PANI‐2 were found to be similar to those with the cured epoxy resin itself. In addition, the similar investigation with an oxetane resin instead of the epoxy resin was also carried out. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 718–726, 2006     

A New Energetic Complex [Co(2,4,3‐tpt)2(H2O)2]·2NO3: Synthesis,Structure, and Catalytic Thermal Decomposition for Ammonium Perchlorate

The energetic complex, [Co(2,4,3‐tpt)₂(H₂O)₂] · 2NO₃ ( 1 ) [2,4,3‐tpt = 3‐(2‐pyridyl)‐ 4‐(4'‐pyridyl)‐5‐(3′‐pyridyl)‐1H‐1,2,4‐triazole], was synthesized and characterized by single‐crystal X‐ray diffraction, thermogravimetric analyses, elemental analysis, X‐ray powder diffraction, and IR spectroscopy. The title complex is a 0D motif with a unit of [Co(2,4,3‐tpt)₂(H₂O)₂]²⁺, whereas NO₃^– ions not only act as counter anions to balance the charge of the Co^II cations, but also provide hydrogen bond interactions, which make the 0D motif into a 1D chain. Furthermore, the thermal decomposition of ammonium perchlorate (AP) with complex 1 was explored by differential scanning calorimetry (DSC) over the temperature range from 50–500 °C. AP is completely decomposed in a shorter time in the presence of complex 1 , and the decomposition heat of the mixture is 2.143 kJ g^–1, significantly higher than pure AP. By Kissinger's method, the ratio of E_a/ln(A) is 11.87 for the mixture, which indicates that complex 1 shows good catalytic activity toward AP decomposition.     

Preparation of NdCrO3 nanoparticles and their catalytic activity in the thermal decomposition of ammonium perchlorate by DSC/TG-MS

Orthorhombic structural perovskite NdCrO₃ nanocrystals with size of 60 nm were prepared by microemulsion method, and characterized by XRD, TEM, HRTEM, SEM, EDS and BET. The catalytic effect of the NdCrO₃ for thermal decomposition of ammonium perchlorate (AP) was investigated by DSC and TG-MS. The results revealed that the NdCrO₃ nanoparticles had effective catalysis on the thermal decomposition of AP. Adding 2% of NdCrO₃ nanoparticles to AP decreased the temperature of thermal decomposition by 87° and increased the heat of decomposition from 590 to 1073 J g⁻¹. Gaseous products of thermal decomposition of AP were NH₃, H₂O, O₂, HCl, N₂O, NO, NO₂ and Cl₂. The mechanism of catalytic action was based on the presence of superoxide ion O₂ ⁻ on the surface of NdCrO₃, and the difference of thermal decomposition of AP with 2% of NdCrO₃ and pure AP was mainly caused by the different extent of oxidation of ammonium.     

MnCo<Subscript>2</Subscript>O<Subscript>4</Subscript> nanoparticles with excellent catalytic activity in thermal decomposition of ammonium perchlorate

MnCo₂O₄ spinel nanoparticles (NPs) have been prepared using Aloe vera gel solution. The characterization of prepared spinel was performed applying Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, transmission electron spectroscope, scanning electron microscope and dynamic light scattering. The results manifested that the prepared nanoparticles were mainly spherical plus minor agglomeration with average size distribution between 35 and 60 nm. The catalytic activity of the prepared nanoparticles upon thermal degradation of ammonium perchlorate (AP) was evaluated applying differential scanning calorimetry and thermogravimetry instruments. MnCo₂O₄ nanoparticles increased the released heat of AP from 450 to 1480 J g^?1 and decreased the decomposition temperature from 420 to 293 °C. The kinetic parameters obtained from Kissinger methods showed that the activation energy of AP thermal decomposition in the presence of MnCo₂O₄ NPs considerably decreased. Also, a mechanism has been proposed in the presence of catalyst for the process of thermal decomposition of AP.     

Design of Advanced MnO/N‐Gr 3D Walls through Polymer Cross‐Linking for High‐Performance Supercapacitor

Three‐dimensional, vertically aligned MnO/nitrogen‐doped graphene (3D MnO/N‐Gr) walls were prepared through facile solution‐phase synthesis followed by thermal treatment. Polyvinylpyrrolidone (PVP) was strategically added to generate cross‐links to simultaneously form 3D wall structures and to incorporate nitrogen atoms into the graphene network. The unique wall features of the as‐prepared 3D MnO/N‐Gr hybirdes provide a large surface area (91.516 m² g^?1) and allow for rapid diffusion of the ion electrolyte, resulting in a high specific capacitance of 378 F g^?1 at 0.25 A g^?1 and an excellent charge/discharge stability (93.7 % capacity retention after 8000 cycles) in aqueous 1 m Na₂SO₄ solution as electrolyte. Moreover, the symmetric supercapacitors that were rationally designed by using 3D MnO/N‐Gr hybrids exhibit outstanding electrochemical performance in an organic electrolyte with an energy density of 90.6 Wh kg^?1 and a power density of 437.5 W kg^?1.     

Self-assembled CuO nanoarchitectures and their catalytic activity in the thermal decomposition of ammonium perchlorate

CuO shuttle-like and flower-like nanocrystals were synthesized through a one-step, low-temperature solution-phase method in the presence of a cation surfactant, hexadecyl trimethyl ammonium bromide. These nanocrystals were studied as an additive for promoting the thermal decomposition of ammonium perchlorate (AP). With the addition of CuO shuttle-like and flower-like nanocrystals, the thermal decomposition temperature of AP decreased. The structure, particle size, and morphology of resulting CuO powders were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Thermogravimetric analysis technique was applied to investigate the thermal decomposition of mixtures of AP and as-prepared CuO nanocrystals.     

Thermal decomposition of ammonium perchlorate activated via addition of NiO nanocrystals

This work reported on the thermal decomposition of ammonium perchlorate activated by addition of NiO nanocrystals with different surface areas. NiO samples were characterized by X-ray diffraction (XRD), transition electron microscope (TEM), Brunauer-Emmett-Teller (BET) technique, Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy. With increasing annealing temperature, the surface areas of NiO samples reduced from 108.6 to 0.9 m² g⁻¹. The catalytic activities of NiO nanocrystals on the thermal decomposition of ammonium perchlorate were investigated by thermogravimetric analysis (TG) coupled with differential thermal analysis (DTA). With addition of NiO nanocrystals, thermal decomposition temperature of AP decreased greatly. Larger surface areas of NiO nanocrystals promoted the thermal decomposition of AP.