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The development of heterogeneous Fenton catalysts with good performance and stability is a challenge in the field of wastewater treatment. In this work, MgAlFe hydrotalcite-like compounds (MgAlFe-HTLcs) were prepared by solid phase reaction at room temperature and modified via a hydrothermal process. The experimental results showed that MgAlFe-HTLcs had a good layered structure with the same proportion of iron and aluminium, 18 h of crystallisation time and 110°C of crystallisation temperature and the lamellar structure was more uniform by solid grinding. Furthermore, the addition of iron can activate H2O2 more effectively to generate active oxygen which is •OH. The degradation experiments demonstrated that nearly 99.0% degradation efficiency was achieved for 10 mg/L Malachite Green (MG) solution within 60 min at the conditions of 0.10 g·L−1 MgAlFe-HTLcs, 0.10 mol·L-1 H2O2 and a natural pH of 6.3. Total organic carbon (TOC) removal reached 72.2% in a 70 min reaction. BET and XRD were measured to further discuss the stability and durability. Finally, a possible mechanism for the degradation of MG was presumed. [ABSTRACT FROM AUTHOR]

Development of high performance room temperature sensors remains a grand challenge for high demand of practical application. Metal oxide semiconductors (MOSs) have many advantages over others due to their easy functionalization, high surface area, and low cost. However, they typically need a high work temperature during sensing process. Here, p-type sensing layer is reported, consisting of pore-rich dumbbell-like Co 3 O 4 particles (DP-Co 3 O 4 ) with intrinsic high catalytic activity. The gas sensor (GS) based DP-Co 3 O 4 catalyst exhibits ultrahigh NH 3 sensing activity along with excellent stability over other structure based NH 3 GSs in room temperature work environment. In addition, the unique structure of DP-Co 3 O 4 with pore-rich and high catalytic activity endows fast gas diffusion rate and high sensitivity at room temperature. Taken together, the findings in this work highlight the merit of integrating highly active materials in p-type materials, offering a framework to develop high-sensitivity room temperature sensing platforms. [ABSTRACT FROM AUTHOR]

The aramid fabric ( AF)-reinforced polyimide ( PI) composites filled with carbon black ( CB) were fabricated by means of a thermal imidization and their mechanical, thermal and electrochemical behaviors were comparatively investigated. Experimental results showed that the tensile strength of composite increased with an increase of the CB, meanwhile, the addition of 5 wt% CB and AF increased the tensile modulus to 5682.0 MPa. The superior mechanical properties of the composites were attributed to the good dispersion and effective stress transfer between the polymer and CB, as evidenced by the results from X-ray diffraction ( XRD) and morphological studies. Besides, the thermal-nonoxidative stability of PI was significantly improved by the incorporation of CB and AF. Furthermore, the CB/ AF/ PI composite was employed as the supercapacitor electrode in the 6 mol/L KOH aqueous electrolyte solution, which exhibited a specific capacitance of 510 F•g−1 at 10 mV•s−1. It also exhibited excellent long-term stability, and the energy density was stable with the increase in the power density. The super performance of the composite electrode is attributed to the synergistic effects of CB particles and organic polymer. [ABSTRACT FROM AUTHOR]

New energetic materials, [Ca(MCZ)3(H2O)2](ClO4)2and {[Ba2(MCZ)4(H2O)2(μ1-ClO4)2(μ2-ClO4)2]0.5}n, are synthesized and tried as alternatives to common primary explosives. Both the crystal structures were determined by single-crystal X-ray diffraction. The crystal of [Ca(MCZ)3(H2O)2](ClO4)2belongs to the monoclinic, P21/c space group,a = 14.168(3) Å,b = 8.5938(18) Å,c = 18.889(4) Å,β = 111.234(2)°,V = 2143.8(8) Å3,ρ = 1.6893 g cm−3, and {[Ba2(MCZ)4(H2O)2(μ1-ClO4)2(μ2-ClO4)2]0.5}nbelongs to the triclinic, P-1 space group,a = 7.166(2) Å,b = 10.461(2) Å,c = 11.738(4) Å,α = 110.563(5)°,β = 93.799(2)°,γ = 96.864(3)°,V = 812.4(4) Å3,ρ = 2.185 g cm−3. Their thermal stabilities were investigated by differential scanning calorimetry (DSC), and exothermic peak temperatures with a heating rate of 10 °C min−1are 249.7 and 181.7 °C, respectively. Non-isothermal reaction kinetics parameters were calculated via both Kissinger’s method and Ozawa-Doyle’s method to work outEK = 124.6 kJ mol−1, lgAK = 10.38,EO = 126.7 kJ mol−1for the calcium complex andEK = 100.3 kJ mol−1, lgAK = 9.50,EO = 102.6 kJ mol−1for the barium complex. Additionally, the critical temperatures of thermal explosion, ΔS≠, ΔH≠, and ΔG≠were calculated as −231.2 J K−1 mol−1, 120.417 kJ mol−1, 236.728 kJ mol−1for the calcium complex and −230.6 J K−1 mol−1, 96.723 kJ mol−1, 195.938 kJ mol−1for the barium complex. As for their explosive nature, sensitivities toward impact and friction were tested. Both [Ca(MCZ)3(H2O)2](ClO4)2and {[Ba2(MCZ)4(H2O)2(μ1-ClO4)2(μ2-ClO4)2]0.5}nare insensitive to friction (>360 N); their impact sensitivities are acceptable (20 and 13 J). Both compounds are energetic complexes. [ABSTRACT FROM PUBLISHER]

Five kinds of graphene nanoplatelet-modified explosive lead styphnate composites (GLS) have been synthesized with different GNPs content from 0.1 to 2.0 mass% and characterized by SEM, XRD and Raman spectra. The initial thermal decomposition behaviours were studied by DPTA, and the complete thermal decompositions were studied by DSC and TG for the everlasting thermal stability of explosives in storage and application. The effects of GNP contents on thermal decomposition were investigated. The evolved gas amount from DPTA test indicates that GLS 1.0 % has the best thermal stability at ambient storage conditions. According to TG and DSC tests, the characteristic temperatures of thermal decomposition ( T and T), the thermodynamic parameters (Δ S, Δ H and Δ G), the kinetic parameters ( E and A) also confirmed this view. The results indicate that the GNP plays two opposite roles in their thermal decomposition processes, the catalysis reaction and hindering thermal conduction. [ABSTRACT FROM AUTHOR]

Two new ionic complexes, (DATr)2[Li2(TNR)2·2H2O]·2H2O (1) and (DATr)[Zn(DATr)Cl3] (2), were synthesized by using 3,4-diamino-1,2,4-triazole (DATr) as outer cation. X-ray single-crystal diffraction analysis revealed that the two complexes crystallize in triclinic and orthorhombic crystal systems, respectively. Differential scanning calorimetry was applied to assess the thermal decomposition behavior and kinetic parameters of decomposition were studied by using Kissinger’s and Ozawa–Doyle’s methods. Furthermore, the critical temperature of thermal explosion and parameters of thermodynamics were obtained. [ABSTRACT FROM PUBLISHER]

Both [Cu(DAT)2(PA)2] (1) and [Cu(DAT)2(HTNR)2] (2) were prepared from 1,5-diaminotetrazole (DAT) and copper trinitrophenol,1for picrate (PA) and2for styphnate acid (2,4,6-trinitro resorcinol, TNR), and were characterized by elemental analysis, FT-IR spectroscopy, and single crystal X-ray diffraction. The space group of these compounds isP21/c(monoclinic). The lattice parameters are similar [a = 11.405(3) Å,b = 14.867(3) Å,c = 8.099(2) Å for1anda = 12.262(3) Å,b = 14.900(3) Å,c = 7.243(2) Å for2], except theβ = 106.257(3)° in1andβ = 92.989(4)° in2. Both have extended structures due to hydrogen bonds, but there are some differences because of the ligands induced effect. Differential scanning calorimetry analysis shows that two exothermic processes take place in both complexes, the first peak temperatures are 488.2 K for1and 519.2 K for2. The kinetic parameters of the first exothermic process were studied by using Kissinger’s method and Ozawa’s method, in which the enthalpy of formation (−7346 and −5706 kJ M−1), critical temperature of thermal explosion (475.0 and 515.8 K), entropy of activation (ΔS≠), enthalpy of activation (ΔH≠), and free energy of activation (ΔG≠) were calculated and obtained as −117.25 J K−1 M−1, 140.64 kJ M−1, 196.44 kJ M−1and −219.1 J K−1 M−1, 383.56 kJ M−1, 495.34 kJ M−1for1and2, respectively. The sensitivity test results showed that both compounds were sensitive to impact (<5 J) and flame (>20 cm) rather than friction. Two similar complexes combined with 1,5-diaminotetrazole (DAT) and copper trinitrophenol were characterized by elemental analysis, FT-IR spectroscopy and single crystal X-ray diffraction and the sensitivity were studied. [ABSTRACT FROM AUTHOR]

The single crystal structure of 1,1′-bis (3,5-dimethyl-pyrazole) methenehydrazine (BDM) was determined by X-ray single crystal diffraction for the first time. The obtained experimental results indicated that BDM was the of 3,6-bis(3,5-dimethylpyrazol-1-yl)-1,4-dihydro-1,2,4,5-tetrazine (BDT), which was the key precursor of s-tetrazine. By this evidence, the preparation mechanism of BDT was proved: At 318.15 K, triaminoguanidine and pentanedione reacted to achieve the (BDM) by molecular and ; when heated to 363.15 K, BDT was then generated by two molecules of BDM with reaction. Furthermore, the properties and also the non-isothermal kinetic parameters have been investigated in the present work. [ABSTRACT FROM AUTHOR]

A new 1D polymeric strontium compound [Sr(tza)2(H2O)2]n was synthesized by reaction of tetrazole-1-acetic acid (Htza) with strontium carbonate, and characterized by X-ray single crystal diffraction, elemental analysis and IR spectroscopy. The central Sr(II) atom is coordinated by eight O atoms from 4 tza- ions and two water molecules. A zigzag chain along the c-axis is constructed by the tridentate tza- anion bridging two Sr(II) atoms. Differential scanning calorimetry (DSC) and thermogravimetric-differential thermogravimetric (TG-DTG) analyses were applied to assess the thermal decomposition behavior. The kinetic parameters were obtained by non-isothermal reaction kinetics, and the Arrhenius equation can be expressed as lnk = 22.17-258.2 × 103/RT. The critical temperature of thermal explosion values, ΔS≠, ΔH≠ and ΔG≠ were obtained at 562 K as, -65.71 J mol-1 K-1, 255.51 kJ mol-1 and 291.78 kJ mol-1, respectively. [ABSTRACT FROM AUTHOR]

The title compound 1, [Mn(H2O)6](AMTZ)2(PA)2, contains 4-animo-3,5-dimethyl-1,2,4-triazole (AMTZ) and picrate (PA) and was characterized by elemental analysis, FT-IR spectroscopy and Single-Crystal X-ray diffraction. The space group of compound 1 is triclinic P-1(2), with a = 6.797(2) Å, b = 9.800(3) Å, c = 13.197(4) Å, α=,β=,γ=. The central Mn2+ is octahedral and surrounded by two kinds of centrosymmetric molecules, AMTZ and PA. The compound has an extended 3-D supramolecular structure due to water molecules coordinated though hydrogen bonds to the nitrogen and oxygen atoms and the offset face-to-face π ··· π packing. The differential scanning calorimetry (DSC) analysis shows that two exothermic processes take place at 341.4°C and 473.9°C. The kinetic parameter of the first exothermic process was studied using Kissinger's method and Ozawa's method. This provided the enthalpy of formation (-3337.7 kJ·mol-1), critical temperature of thermal explosion (588.79 K). The entropy of activation (ΔS≠), enthalpy of activation (ΔH≠), and free energy of activation (ΔG≠) were, respectively, -209.78 J·K-1·mol-1, 155.50 kJ·mol-1 and 267.75 kJ·mol-1. A flame sensitivity test showed that the 50% firing height (h50) was 20 cm. [ABSTRACT FROM AUTHOR]

Cadmium(II) imidazole (IMI) azide [Cd(IMI)2(N3)2]n(1) was synthesized using imidazole and azide, and was characterized by the elemental analysis and FTIR spectrum. The crystal structure was determined by X-ray single crystal diffraction, and the crystallographic data show that the crystal belongs toorthorhombic,Pba2space group,α = 10.780(4) Å,b = 13.529(5) Å, andc = 3.6415(12) Å. Its crystal density is 2.080 g·cm–3. Cd(II) is a six-coordinate with six nitrogens from four imidazoles and two azides withμ–1,1 coordination. The thermal decomposition mechanism was determined based on differential scanning calorimetry (DSC) and thermogravimetry-derivative thermogravimetry (TG-DTG) analysis, and the kinetic parameters of the first exothermic process were studied using Kissinger’s method and Ozawa’s method, respectively. The energy of combustion, enthalpy of formation, critical temperature of thermal explosion, entropy of activation (ΔS≠), enthalpy of activation (ΔH≠), and free energy of activation (ΔG≠) were measured and calculated. In the end, impact sensitivity was also determined by standard method. [ABSTRACT FROM AUTHOR]

Two new multi-ligand coordination compounds of copper(ii) ethylenediamine (en) azide and cobalt(iii) ethylenediamine azide, [Cu2(en)2(N3)4]n (1) and Co(en)2(N3)2(NO3) (2), were synthesized and characterized by elemental analysis and FT-IR spectroscopy. The crystal structures were determined by X-ray single crystal diffraction. The obtained results show that the crystals of 1 and 2 belong to the monoclinic, C2/c space group. The metal cations are six-coordinated with the azido ligands and ethylenediamine molecules through nitrogen atoms. The coordination modes of the azido-groups were μ-1, μ-1,1 and μ-1,1,3 modes for 1, and μ-1 mode for 2. Under a nitrogen atmosphere, with a heating rate of 5 K min−1, the thermal decompositions contain two main exothermic stages in the DSC curves corresponding to the TG-DTG curves. The non-isothermal kinetics parameters were calculated by the Kissinger's method and Ozawa's method, respectively. The energies of combustion, enthalpies of formation, critical temperature of thermal explosion, entropies of activation (ΔS≠), enthalpies of activation (ΔH≠), and free energies of activation (ΔG≠) were measured and calculated. The sensitivity properties were also determined with standard methods and the results showed that 1 had a much higher flame sensitivity and lower impact sensitivity. [ABSTRACT FROM AUTHOR]

Abstract: A multifunctional heterojunctioned K-OMS-2/TiO2/Fe3O4 (KTF) nanocomposite was successfully synthesized using a combination of hydrothermal and co-precipitation techniques. The resultant sample was characterized by XRD, FESEM, TEM, N2 adsorption, XPS and VSM. Its photocatalytic activity was demonstrated in the photocatalytic degradation of humic acid (HA). Morphology characterization showed the hierarchical structure of the synthesized material, and XRD results revealed that both the rutile and anatase TiO2 structures are present in the sample. The average pore diameters and BET surface area of the synthesized KTF heterojunctions were 40nm and 134.42m2/g, respectively. XPS spectra confirmed the presence of Fe3O4 and TiO2 in the synthesized material, and the valences of Mn were kept at +3 and +4 after the grafting of Fe3O4 and TiO2. The synthesized material showed good magnetic response and photocatalytic activity under simulated solar light irradiation, and 85.7% of HA was decomposed after 120min in the presence of KTF nanocomposites. The reusability study suggested that the magnetic recovered material was stable enough for multiple recycling usages, verifying its potential application in water purification. [Copyright &y& Elsevier]

First-principles methods using the TPSS density functional level of theory with the basis set 6-31G** were applied to study (5-cyanotetrazolato-N) pentaammine cobalt (III) perchlorate (CP) and Ni, Fe and Zn analogues in the gas phase. The optimized lowest-energy geometry of CP was calculated from reported experimental structural data using the TPSS method. The calculated values are in good agreement with those measured by X-ray diffraction. Ni, Fe and Zn analogues were constructed and calculated on the same basis. NBO results showed that the metal-ligand interactions have covalent character. Donor-acceptor analyses predicted that the delocalization energy E decreases from Co to Zn, so the covalent nature of the complexes increases in the order Co>Fe>Ni>Zn. In addition, HOMO-LUMO composition was investigated to determine the stability of the title compounds. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Abstract: A novel hybrid process combining β-MnO2 nanowires oxidation and microfiltration was adopted to remove bisphenol A (BPA), an endocrine disrupting chemical (EDC) in the aquatic environment. The β-MnO2 nanowires synthesized via a facile hydrothermal method were characterized by X-ray diffraction, transmission electron microscopy, field-emission scanning electron microscope, and nitrogen sorption. It was demonstrated that β-MnO2 nanowires can degrade BPA effectively. Investigation on operation parameters indicated that oxidation of BPA using β-MnO2 nanowires was evidently dependent on pH, while humic acid and coexisting metal ions such as Ca2+, Mg2+, and Mn2+ induced suppressive effects. After oxidation, a crossflow microfiltration process was conducted to efficiently separate and recover the β-MnO2 nanowires from treated water. Membrane fouling study showed that the as-synthesized β-MnO2 nanowires possess excellent mechanical stability and was able to retain the 1D structure with high aspect ratios after reaction, thus significantly reducing membrane pore blocking in the microfiltration process. [Copyright &y& Elsevier]

Abstract: N-type Fe2O3 nanobelts and P-type LaFeO3 nanobelts were prepared by electrospinning. The structure and micro-morphology of the materials were characterized by X-ray diffraction (XRD) and scanning of electron microscopy (SEM). The gas sensing properties of the materials were investigated. The results show that the optimum operating temperature of the gas sensors fabricated from Fe2O3 nanobelts is 285°C, whereas that from LaFeO3 nanobelts is 170°C. Under optimum operating temperatures at 500ppm ethanol, the response of the gas sensors based on these two materials is 4.9 and 8.9, respectively. The response of LaFeO3-based gas sensors behaves linearly with the ethanol concentration at 10–200ppm. Sensitivities to different gases were examined, and the results show that LaFeO3 nanobelts exhibit good selectivity to ethanol, making them promising candidates as practical detectors of ethanol. [Copyright &y& Elsevier]

ZnO microcrystals are synthesized through a facile solution method and characterized by field-emission scanning electron microscopy, transmission electron microscopy, selected area electron diffraction and X-ray diffraction. The ethanol sensing properties of these microcrystals are investigated by spin-coating them on a silicon substrate with Pt electrodes to fabricate a micro-structure sensor. The sensitivity is up to 8 when the sensor is exposed to 50 ppm ethanol, and the response time and recovery time are 10 s and 20 s, respectively. A contact-controlled model is established to explain the sensing properties of the microcrystals, which provides another approach to realize high-performance gas sensors. [ABSTRACT FROM AUTHOR]

Abstract: Large-scale uniform nutlike ZnO microcrystals are successfully synthesized via a facile hydrothermal process at low temperature (95 °C). The structure and morphology of the ZnO products are characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The results reveal that the as-prepared ZnO products have average length of 2.2 µm and diameter of 1.8 µm, possessing a single crystal wurtzite structure. The possible formation mechanism of nutlike microcrystals is proposed. The samples exhibit excellent ethanol sensing properties at the operating temperature of 250 °C detecting ethanol as low as 1 ppm. [Copyright &y& Elsevier]

Abstract: KCl-doped ZnO nanofibers are synthesized via an electrospinning method and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The humidity sensing properties of these nanofibers are investigated by screen-printing them on a ceramic substrate with a pair of Ag–Pd interdigitated electrodes. The experimental results show that the 5.7wt% KCl-doped ZnO nanofibers hold super-rapid response and recovery, high response value, good reproducibility, linearity, selectivity, and stability at 100Hz. Especially, the response time and recovery time is only about 2 and 1s, respectively. These results demonstrate the potential application of KCl-doped ZnO nanofibers for fabricating high performance humidity sensors. [Copyright &y& Elsevier]

Abstract: Cu–Zn/ZnO nanocomposites with a novel core-shell structure have been prepared by a surface precipitation process in aqueous solution. X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy are employed to analyze the structure and morphology of the present products. The influence of the annealing temperature on the core-shell structure of the nanocomposites is investigated, and a possible growth model is proposed. Furthermore, the gas sensors based on the Cu–Zn/ZnO nanocomposites are fabricated and tested, which exhibits high sensitivity and fast response to CO. The best results are obtained for the sensor based on the film annealed at 350°C, which shows that the sensitivity is about 6.3 when the sensor is exposed to 100ppm CO at the operating temperature of 240°C. The possible sensing mechanism of the Cu–Zn/ZnO sensing film has also been discussed. [Copyright &y& Elsevier]

Abstract: Dumbbell-like ZnO microcrystals have been obtained through a facile solution method. The structure, morphology and optical properties of the as-prepared ZnO microcrystals have been characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy and photoluminescence. The as-prepared ZnO microcrystals exhibit excellent sensing properties against acetone at an operating temperature of 300°C. The response and recovery times are found to be 1.5 and 3s, respectively. Moreover, the sensor holds the successful discrimination between acetone and ethanol, which makes our product a good candidate in fabricating highly selective sensors in practice. [Copyright &y& Elsevier]

Abstract: Pure and Sm2O3-doped SnO2 are prepared through a sol–gel method and characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The sensor based on 6wt% Sm2O3-doped SnO2 displays superior response at an operating temperature of 180°C, and the response magnitude to 1000ppm C2H2 can reach 63.8, which is 16.8 times larger than that of pure SnO2. This sensor also shows high sensitivity under various humidity conditions. These results make our product be a good candidate in fabricating C2H2 sensors. [Copyright &y& Elsevier]

The environmental friendly energetic coordination compound Zn(DAT)2(Ac)2 ( 1) (Ac = acetic) was synthesized from 1,5-diaminotetrazole (DAT), and characterized by elemental analysis and FT-IR spectroscopy. The crystal structure was determined by X-ray single crystal diffraction. The crystallographic data showed that compound 1 belongs to the monoclinic system, space group Cc, with cell parameters: a = 17.595(5) Å, b = 7.3060(18) Å, c = 14.076(4) Å, β = 123.449(4)°, V = 1509.7(7) Å3, Z = 4, Dc = 1.688 g ·cm-3. In 1, the zinc cation is four-coordinated with two oxygen atoms from the two acetic carboxyl groups and two 4-nitrogen atoms of DAT molecules, and exhibits a distorted-tetrahedron configuration. Thermal decomposition mechanism was determined based on differential scanning calorimeter (DSC) and thermogravimetry-derivative thermogravimetry (TG-DTG) analysis. Kinetic parameters of the first exothermic process were studied by using Kissinger's method and Ozawa's method, respectively. The critical temperature of thermal explosion, entropy of activation (Δ S≠), enthalpy of activation (Δ H≠), and free energy of activation (Δ G≠) were calculated and obtained as 519.71 K, -144.04 J ·(K ·mol)-1, 152.20 kJ ·mol-1 and 224.99 kJ ·mol-1, respectively. The constant-volume energy of combustion (9.78 MJ ·kg-1) was measured by oxygen bomb calorimetry, which was equal to that of RDX. In the end, the sensitivities properties were also determined with standard method. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • In this work, the obtained Zn 2 SnO 4 -RGO hybrids exhibited outstanding sensing performance for detecting oxidizing gases (NO 2 and O 3) with very low cross sensitivities to reducing gases, such as C 2 H 5 OH, CH 3 COCH 3 and CO. • The Zn 2 SnO 4 -RGO based sensors exhibited high response values of up to 3.50 for 500 ppb NO 2 , which is higher than that for detection of 500 ppb O 3 (1.78) at 30 °C under 50% relative humidity (RH). • The surface reaction between Zn 2 SnO 4 -RGO hybrids and NO 2 can be concluded from Operando diffuse reflectance infrared Fourier transformed spectroscopy (Operando DRIFT). Abstract Highly selective oxidizing gas sensors are of great importance for environmental pollution monitoring. In this work, a hybrid material containing Zn 2 SnO 4 nanoparticles (NPs) and immobilized reduced graphene oxide (Zn 2 SnO 4 -RGO) was developed as a high performance gas sensing material for the detection of ppb-levels of oxidizing gases (NO 2 and O 3). The structural, morphological and compositional properties of the Zn 2 SnO 4 -RGO hybrids were systematically characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS), which demonstrated the successful anchoring of Zn 2 SnO 4 NPs on RGO nanosheets. The obtained Zn 2 SnO 4 -RGO hybrids exhibited outstanding sensing performance for detecting oxidizing gases (NO 2 and O 3) with very low cross sensitivities to reducing gases, such as C 2 H 5 OH, CH 3 COCH 3 and CO. The Zn 2 SnO 4 -RGO based sensors exhibited high response values of up to 3.50 for 500 ppb NO 2 , which is higher than that for detection of 500 ppb O 3 (1.78) at 30 °C under 50% relative humidity (RH). Moreover, the NO 2 sensing performances of Zn 2 SnO 4 -RGO-based sensors were investigated under various RH. In all cases, the sensors based on RGO and Zn 2 SnO 4 -RGO hybrids presented p-type behavior. The sensors based on Zn 2 SnO 4 -RGO hybrids also exhibited high response values of up to 3.62 for 1 ppm NO 2 at 50 °C in 80% RH, which is much higher than that of pure RGO (1.31). The excellent sensing performances are mainly ascribed to the synergetic effect of Zn 2 SnO 4 NPs and RGO. Furthermore, the surface reaction between Zn 2 SnO 4 -RGO hybrids and NO 2 can be concluded from Operando diffuse reflectance infrared Fourier transformed spectroscopy (Operando DRIFT). [ABSTRACT FROM AUTHOR]

Doping and high specific area are essential to the performance of supercapacitor electrode materials. However, the conventional single doping in two dimensional electrode materials is still unable to get high supercapacitive performance. Here we report a facile hydrothermal process using ammonia as a source of nitrogen (N) and thiourea as a sulfur (S) source to prepare N/S co-doped three dimensional (3D) graphene hydrogel (N/S-3DGH) for supercapacitor electrode application. The as-prepared N/S-3DGH is uniform and stable. The N/S co-doped 3DGH electrode material exhibits a high specific capacity of 1063 Cg -1 at a current density of 1 Ag -1 . Even at a density of 20 Ag -1 , it can still hold an excellent charge and discharge cycling stability, and with 76% of initial capacity retained after 6000 charge and discharge cycles at a density of 10 Ag -1 . Moreover, the all-symmetric solid-state supercapacitor fabricated by N/S-3DGH without any binders owned an energy density of 6.25 Wh kg −1 at a power density of 500 W kg −1 showing very promising applications for portable power and flexible energy storage devices. [ABSTRACT FROM AUTHOR]

In this work, core-shell WO 3 -SnO 2 (CS-WS) nanofibers (NFs) have been successfully synthesized via a coaxial electrospinning approach. The structure and morphology characteristics of the resultant products were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectra (XPS). To investigate the sensing mechanism of the CS-WS NFs, sensors based on SnO 2 NFs, WO 3 NFs, and SnO 2 -WO 3 composite NFs were fabricated respectively, and their gas sensing properties were investigated by using CO, ethanol, toluene, acetone, and ammonia as the test gas. The results indicated that the CS-WS NFs exhibited a good response to ethanol (5.09 at 10 ppm) and short response/recovery time (18.5 s and 282 s) compared with the other test gases. The enhanced ethanol sensing properties of CS-WS NFs compared with those of SnO 2 NFs were closely associated with the CS structure and its derivative effect due to the different work function of SnO 2 and WO 3 . The approach proposed in this study may contribute to the realization of more sensitive metal oxide semiconductor (MOS) core-shell heterostructure sensors. [ABSTRACT FROM AUTHOR]

Transition metal oxides have attracted considerable attention as anode materials of lithium-ion batteries (LIBs). However, poor electrical conductivity and huge volume change hinder their practical application. Porous nanostructure is vital to attain high-performance lithium-ion batteries. Herein, we have designed and fabricated regularly porous ZnFe 2 O 4 nanospheres consisted of small primary nanoparticles via a facile hydrothermal method followed by calcination. The structural properties and morphology of the sample are characterized by powder X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy. The composite is then evaluated as anode for Li-ion battery and shows excellent electrochemical properties. The reversible capacity of 868.9 mAh g −1 can be obtained at 200 mA g −1 over 80 cycles. Furthermore, the discharge capacity can still retain 456 mAh g −1 after 600 cycles at a high charge rate of 2 A g −1 . Our findings reveal that ZnFe 2 O 4 sample is a promising anode material for LIBs due to its superior rate capability and long cycle life. [ABSTRACT FROM AUTHOR]

Magnesium azotetrazole-1,1'-dioxide (1) was first prepared and intensively characterized by single-crystal X-ray diffraction, IR spectroscopy, mass spectrometry, elemental analysis, and DSC measurements. The heat of formation was calculated using the atomization energy method based on quantum chemistry and the heat of detonation was also predicted. The NBO analysis was performed for inspecting charge distributions. The sensitivities towards impact and friction were tested using the BAM standard. The high detonation performance (5289 kJ·kg-1), good thermal stabilities (245.5 °C) and excellent insensitivity (39.2 J and >360 N) as well as clean decomposition products supports it of great interest as a promising candidate of green insensitive energetic materials. [ABSTRACT FROM AUTHOR]

A reticular 3D energetic metal-organic framework, sodium 1,1′-dinitramino-5,5′-bistetrazolate was first synthesized and fully characterized by crystal X-ray diffraction, elemental analysis, mass spectrometry, IR spectroscopy, differential scanning calorimetry (DSC) and sensitivity test. It shows a density of 1.892 g·cm −3 , a positive oxygen balance and a high decomposition temperature of 250 °C. The promising energetic properties were also investigated by using theoretical calculation methods. Its calculated heat of formation (529.5 kJ·mol −1 ) combined with impressive heat of detonation (5080 kJ·kg −1 ), good thermal stabilities and clean detonation products make it a competitive replacement as a green energetic material. [ABSTRACT FROM AUTHOR]

Pt-loaded mesoporous WO 3 was fabricated by nanocasting method. Mesoporous structure provided ordered tunnel which was convenient for gas diffusion and the large specific surface area which could offer more active sites. The noble metal (Pt) improved the catalytic efficiency which played crucial role in enhancing the performance of the gas sensor. The obtained materials were characterized by X-ray diffraction (XRD), Brunauer-Emmet-Teller (BET), Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Characterization indicated that the synthesized materials had ordered mesoporous structure with excellent crystallinity and the pore size was about 10.6 nm. Static test system was employed to measure ammonia sensing properties for the as-prepared samples. The sensor based on Pt-loaded WO 3 presented higher sensitivity, quicker response-recovery rates, excellent repeatability and selectivity. It indicated that the Pt-loaded mesoporous WO 3 was a potential ammonia gas sensor material. [ABSTRACT FROM AUTHOR]

The development of graphene-based room temperature gas sensors has drawn massive attention due to their unique advantage of gas sensing at room temperature. In this paper, in pursuit of developing high-performance graphene-based gas sensors, a NO 2 gas sensor has been successfully fabricated using sulfonated reduced graphene oxide (S-rGO) anchoring with SnO 2 nanoparticles as sensing materials. The SnO 2 nanoparticles modified S-rGO (SnO 2 /S-rGO) hybrids were prepared by deposition of SnO 2 nanoparticles on the surface of S-rGO through hydrothermal synthesis method. The combined characterizations of X-ray diffraction, UV–vis spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, energy-dispersive spectroscopy, as well as N 2 sorption isotherm indicate the successful preparation of SnO 2 /S-rGO hybrids with porous structure. Most importantly, SnO 2 /S-rGO hybrids exhibit good sensing performances for detection of NO 2 at room temperature, such as high response, fast response and recovery rate, and good selectivity. The sensor based on SnO 2 /S-rGO hybrids exhibits better sensing performances than the previously reported rGO-based gas sensors. Furthermore, the excellent sensing performances of sensor based on SnO 2 /S-rGO also render it suitable for development of high performance gas sensors operated at room temperature. [ABSTRACT FROM AUTHOR]

Through a one-pot reaction of NiCO3 ·2Ni(OH)2 ·H2O, aminourea hydrochloride (SCZ ·HCl) and 2,4,6-trinitroresorcinol (TNR), a halogen-free and lead-free chelating energetic material (CEM) [Ni(SCZ)3]TNR was synthesized. We confirmed the structure of [Ni(SCZ)3]TNR by infrared spectroscopy, X-ray diffraction, and elemental analysis. The complex is triclinic with P $\bar{1}$(2)/ n space group. Cell parameters are: a = 1.04008(17) nm, b = 1.3719(2) nm, c = 1.4897(2) nm, V = 2.0337(6) nm3, Z = 4. The central nickel atom is six-coordinate with three oxygen atoms of carbonyl groups and three terminal nitrogen atoms of the hydrazine groups from three SCZs to form a distorted octahedron. Differential scanning calorimetry and analysis applied to assess the thermal decomposition behavior. The DSC curve with a linear heating rate of 10 °C ·min-1 shows that [Ni(SCZ)3]TNR is thermally stable with one exothermic peak temperatures of 78.8 °C and two exothermic peak temperatures of 216.8 °C and 308.1 °C. The kinetic parameters were obtained by non-isothermal reaction kinetics. The equation can be expressed as ln k = 24.49-243.3 × 103/ RT. Moreover, the values of the critical temperature of thermal explosion, Δ S≠, Δ H≠, Δ G≠, and the enthalpies of formation were obtained as 206.5 °C, -145.543 J ·mol-1 ·K-1, 237.18 kJ ·mol-1, 305.84 kJ ·mol-1, and -2.65 MJ ·kg-1, respectively. [ABSTRACT FROM AUTHOR]

The heptacoordinate transition metal coordination compound [Cd(SCZ)3(H2O)](PA)2 ·3H2O ( 1) with the ligand semicarbazide (SCZ) and the counteranion picrate (PA) was synthesized and characterized by elemental analysis and FTIR spectroscopy. Single-crystal X-ray diffraction analysis revealed that 1 crystallizes in the monoclinic space group P21/ c. The Cd2+ ion is heptacoordinated by three SCZ groups and a water molecule. SCZ presents typical bidentate coordination modes. The thermal decomposition mechanism of 1 was studied by differential scanning calorimetry (DSC), which revealed that complex 1 exhibits three small endothermic and two large exothermic processes. The non-isothermal kinetics parameters were calculated by the Kissinger's method and Ozawa-Doyle's method, respectively. The heat of combustion was measured by oxygen bomb calorimetry. The enthalpy of formation, the critical temperature of thermal explosion, the entropy of activation (Δ S≠), the enthalpy of activation (Δ H≠), and the free energy of activation (Δ G≠) were also calculated. Sensitivity tests revealed that 1 is insensitive to mechanical stimuli. [ABSTRACT FROM AUTHOR]

Lithium chloride (LiCl)-loaded 3D cubic mesoporous silica KIT-6 (LiCl-KIT-6) composites were prepared as resistance-type humidity-sensitive materials. The structures of the resultant composites were characterized by X-ray diffraction, N 2 adsorption–desorption, and transmission electron microscopy. The humidity sensors based on LiCl-KIT-6 composites were fabricated and the sensing properties were investigated. Results indicate the uniform pore distribution of KIT-6 contributes to the rapid hydrone transport in mesoporous channels. The impedance of optimized 3 wt% LiCl-KIT-6 sensor changed by more than three orders of magnitude over the relative humidity range of 11–95%. The response and recovery times of the sensor were 15 s and 28 s, respectively. Finally, the complex impedance method was used to analyze the humidity sensing mechanism of the sensor based on LiCl-KIT-6. [ABSTRACT FROM AUTHOR]

A facile and effective strategy has been successfully developed to synthesize reduced graphene oxide-multiwalled carbon nanotubes-tin oxide nanoparticles (rGO-CNT-SnO 2 ) hybrids by hydrothermal method. The combined characterizations of X-ray diffraction, Raman spectrum and Transmission electron microscopy were used to characterize the samples thus obtained, indicating the successful preparation of rGO-CNT-SnO 2 hybrids. A room temperature NO 2 sensor was fabricated by dropping the dispersion of rGO-CNT-SnO 2 hybrids on the surface of ceramic substrate previously printed Au electrodes. Most importantly, the sensor based on rGO-CNT-SnO 2 hybrids shows high response, fast response and recovery rate, high selectivity and good stability, which are much better than NO 2 sensors based on pure rGO and rGO-SnO 2 hybrids. [ABSTRACT FROM AUTHOR]

Two heterocyclic-based energetic ionic salts were synthesized from 4-amino-3-hydrazino-5-mercapto-1, 2,4-triazole ( 1), which was used as proton bases reacting with nitric or perchloric acid. They were characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. In addition, their combustion heats were measured by oxygen bomb calorimetry and their heats of formation were predicted based on the combustion heats data. The non-isothermal kinetics parameters were calculated by Kissinger's method and Ozawa-Doyle's method, respectively. The critical temperature of thermal explosion and the thermodynamic parameters were also obtained by DSC results. The energetic properties and thermal analyses confirmed that the two salts maybe have potential application in the field of energetic materials. [ABSTRACT FROM AUTHOR]

Highly sensitive and selective toluene sensors based on ordered mesoporous Co3O4 have been successfully developed. The combined characterizations of X-ray diffraction (XRD) patterns, nitrogen adsorption–desorption isothermal, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) indicate that mesoporous Co3O4 with ordered mesoporous structure and high surface area has been successfully prepared by the nanocasting method using mesoporous silica (SBA-15) as hard template and Co(NO3)2·6H2O as cobalt source. It is also found that mesoporous Co3O4 thus obtained shows good response toward toluene with the concentrations ranging from 1ppm to 1000ppm. Furthermore, mesoporous Co3O4 also exhibits high selectivity for detection of toluene, compared to other interferences, such as ethanol, formaldehyde, ethanol, acetone, methanol and ammonia. Most importantly, mesoporous Co3O4 exhibits better sensing performance than that of non-porous Co3O4 obtained by direct calcination of Co(NO3)2·6H2O in the absence of any templates, which can be attributed to unique properties of mesopotous Co3O4, such as high surface area, open mesoporous structure as well as relatively small crystal size. [ABSTRACT FROM AUTHOR]

The green nitrogen-rich coordination compound Zn3(ATZ)6(N3)6 ( 1) (ATZ = 4-amino-1,2,4-triazole) was prepared and characterized by elemental analysis, IR spectroscopy, DSC and TG/DTG analyses. Its crystal structure was determined through X-ray single crystal diffraction at 153(2) K. The crystal belongs to the monoclinic P21/ n space group with crystal parameters of the unit cell dimensions: a = 0.9187(3) nm, b = 1.4109(4) nm, c = 1.3395(4) nm, β = 92.593(4)°, V = 1.7345(8) nm3, Z = 4, Dc = 1.824 g ·cm-3. The kinetic parameters of the first exothermic process of 1 were studied by the Kissinger's method and Ozawa-Doyle's method. Sensitivity tests revealed that 1 is insensitive to mechanical stimuli. [ABSTRACT FROM AUTHOR]

Two energetic ionic salts DATr ·NTO ( 2) and DATr ·TNR ( 3) of 3,4-diamino-1,2,4-triazole (DATr) ( 1) were synthesized by reaction of 3,4-diamino-1,2,4-triazole with either 3-nitro-1,2,4-triazole-5-one (NTO) or 2,4,6-trinitro-resorcinol (TNR) in aqueous solution. Their structures were characterized by FT IR spectroscopy (FT-IR) and X-ray single-crystal diffraction analysis. Their molecular structure and crystal structure were determined. They belong to the monoclinic crystal system, space group P21/ c. The crystal density is 1.693 g ·cm-3 and 1.738 g ·cm-3, respectively. The thermal decomposition characteristics of the title compounds were investigated using differential scanning calorimetry (DSC) and thermogravimetry/differential thermogravimetry (TG/DTG) technologies. Furthermore, the sensitivity properties were determined by standard methods. [ABSTRACT FROM AUTHOR]

Abstract: Mesoporous LaFeO3 with high surface area and pore volume was prepared through a nanocasting route by using mesoporous silica SBA-15 as a hard template. The structure and chemical composition of the sample were characterized by X-ray diffraction (XRD), nitrogen adsorption–desorption, transmission electron microscopy (TEM) and inductively coupled plasma mass spectrometry (ICP-MS). The humidity sensing properties of the mesoporous LaFeO3 were investigated. Impedance greatly changes by more than five orders magnitude (1.7×106 to 4.5kΩ) when the relative humidity varies from 11% to 98% at 10Hz, and it also exhibits the satisfactory response time, hysteresis and stability. The sensor utilizing mesoporous LaFeO3 via nanocasting method displays superior humidity performance compared to that using bulk LaFeO3 via sol–gel technique. Such sensing behavior of the mesoporous LaFeO3 can be attributed to the high surface area (83.2m2/g) and porosity, which lead to highly effective interaction between the water molecules and the surface active sites. A possible mechanism is discussed to explain the excellent performance of the humidity sensing device using the mesoporous LaFeO3. [Copyright &y& Elsevier]

The intriguing multi-ligand compound [Cu(IMI)4Cl]Cl ( 1) with the ligand imidazole (IMI) was synthesized and characterized by elemental analysis and FT-IR spectroscopy. The crystal structure was determined by X-ray single crystal diffraction and the crystallographic data showed that the compound belongs to the monoclinic P21/ n space group [ α = 8.847(2) Å, b = 13.210(3) Å, c = 13.870(3) Å, and β = 90.164(3)°]. Furthermore, the CuII ion is five-coordinated by four nitrogen atoms from four imidazole ligands and a chlorine atom. The thermal decomposition mechanism was determined based on differential scanning calorimetry (DSC) and thermogravimetric (TG-DTG) analysis. The non-isothermal kinetics parameters were calculated by the Kissinger's method and Ozawa's method, respectively. The energy of combustion, enthalpy of formation, critical temperature of thermal explosion, entropy of activation (Δ S≠), enthalpy of activation (Δ H≠), and free energy of activation (Δ G≠) were measured and calculated. [ABSTRACT FROM AUTHOR]

Abstract: La x Sr1− x FeO3 nanofibers were synthesized via electrospinning and characterized by field-emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). The diameters of the La x Sr1− x FeO3 nanofibers produced were in the range of 30–80nm. When the La/Sr ratio was 0.7:0.3, La0.7Sr0.3FeO3 nanofibers showed high and rapid response and good repeatability to 500ppm ethanol. At 185°C, the response and recovery time of La0.7Sr0.3FeO3 nanofiber were 11s and 21s, respectively. The La0.7Sr0.3FeO3 nanofibers are promising sensitive materials for ethanol detecting. [Copyright &y& Elsevier]

Abstract: Uniaxially aligned Ba0.8Sr0.2TiO3 (BST) nanofiber arrays were fabricated via electrospinning combined with annealing. A specially designed collector composed of two paralleled aluminum electrodes and an insulative substrate were used in the electrospinning process. The morphology and structure of the resultant arrays were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The SEM shows well uniaxial arrangement and the diameters before (300–500nm) and after (100nm) calcination. XRD shows well-defined perovskite crystal structure of the as-synthesized arrays. The humidity sensor based on the as-synthesized arrays exhibited a rapid response-recovery property at room temperature. The possible sensing mechanism was proposed. [Copyright &y& Elsevier]

Abstract: SnO2 nanosheets were synthesized by a hydrothermal method at 200°C using stannic chloride hydrate and sodium hydroxide as starting materials. The as-synthesized nanoparticles and nanosheets are characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The gas response, selectivity, and response speed were optimized by varying the morphology of the sensing materials and operation temperature. Most importantly, the SnO2 nanosheets sensor exhibits high response, low detection limit and fast response to ethanol. The gas response of the SnO2 nanosheets to 100ppm ethanol was 39.6 at 300°C, which was 3.6 and 6.1 times higher than that of the nanospheres-like and the nanoparticles, respectively. Response and recovery times were 1 and 9s when the sensor was exposed to 20ppm ethanol at an operating temperature of 300°C. [Copyright &y& Elsevier]

Abstract: WO3 nanofibers were synthesized using an electrospinning method and characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The obtained WO3 nanofibers were used as sensitive materials for the detection of NH3. Indirect-heating sensors based on WO3 nanofibers were prepared. When the WO3 nanofiber-based sensors were exposed to 100ppm NH3 at 500°C, the response is 5.5, and the response and recovery times are 1 and 5s, respectively. These results indicate that the gas sensors based on WO3 nanofibers express high and fast response and recovery characteristics to NH3, and the WO3 nanofibers are promising sensitive materials for NH3 detecting. [Copyright &y& Elsevier]

Abstract: Hollow ZnSnO3 microspheres were successfully prepared by hydrothermal method at 160°C for 12h. The prepared material was characterized by field emission scanning electron microscope (FESEM), transmission electron microscope (TEM) and X-ray diffraction measurements (XRD). The average diameter of the hollow ZnSnO3 microspheres was in the range of 400–600nm. Compared with solid ZnSnO3 microspheres structure, the hollow ZnSnO3 microspheres showed better response (S) to butane. To 500ppm butane, the sensor response (S) of the hollow ZnSnO3 microspheres was 5.79 at the optimum operating temperature of 380°C, and the response and recovery time were 0.3s and 0.65s, respectively. The sensitivities of sensors based on this material were linear with the concentration of butane in the range of 100–1000ppm. [Copyright &y& Elsevier]

Abstract: K2CO3-SBA-15 with different K2CO3 content was prepared by thermal dispersion. The structures of resultant powders were characterized by XRD, N2 adsorption and IR. The humidity sensing properties of the powders were also investigated. Compared with pure SBA-15, K2CO3-SBA-15 shows improved humidity sensing properties and the introducing level of K2CO3 has a great influence on the humid sensitivity of K2CO3-SBA-15 composites. The optimal mixing ratio was K2CO3-SBA-15 (0.8g/g), which exhibited excellent linearity in the whole range of 11–95%RH, a resistance variation of about five orders of magnitude, and a rapid response time and recovery time about 15 and 50s, respectively. The mechanism of the humidity sensitive properties was also discussed. [Copyright &y& Elsevier]