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1.
Front Chem ; 9: 666450, 2021.
Article de Anglais | MEDLINE | ID: mdl-34490204

RÉSUMÉ

In recent years, the wide application of fluoride materials has grown rapidly, therefore excessive discharge in the surrounding environment, especially in drinking water and organic effluent, has become a potential hazard to humans, and has even resulted in fluorosis disease. The development of a highly effective and convenient method to recognize fluoride anions in surrounding environments seems necessary and urgent. Among which, the development of a colorimetric and fluorescence fluoride chemosensor with obvious color changing allowing for naked-eye detection with high sensitivity and selectivity is more interesting and challenging. In this minireview, current novel colorimetric and fluorescence chemosensors for fluoride anions by hydrogen-bond interaction are introduced, including obvious color changing by naked-eye detection, high sensitivity and selectivity, non-pollution and fluoride extraction ability, aqueous detection, and other additional functions. Finally, the perspective of the fluoride chemosensor design concept and potential evolution trends are pointed out.

2.
Front Chem ; 9: 664504, 2021.
Article de Anglais | MEDLINE | ID: mdl-33816442

RÉSUMÉ

Current high-efficiency hybrid perovskite solar cells (PSCs) have been fabricated with doped hole transfer material (HTM), which has shown short-term stability. Doping applied in HTMs for PSCs can enhance the hole mobility and PSCs' power conversion efficiency, while the stability of PSCs will be significantly decreased due to inherent hygroscopic properties and chemical incompatibility. Development of dopant-free HTM with high hole mobility is a challenge and of utmost importance. In this review, a series of selected and typical π-conjugated dopant-free hole transport materials, mainly regarding small molecules, are reviewed, which could consequently help to further design high-performance dopant-free HTMs. In addition, an outline of the molecular design concept and also the perspective of ideal dopant-free HTMs were explored.

3.
RSC Adv ; 11(16): 9542-9549, 2021 Mar 01.
Article de Anglais | MEDLINE | ID: mdl-35423470

RÉSUMÉ

The influence of temperature and solvent on the solid-liquid ternary phase diagrams of the 2HNIW·HMX cocrystal has been investigated. Ternary phase diagrams were constructed for the 2HNIW·HMX cocrystal in acetonitrile and ethyl acetate at 15 °C and 25 °C. HMX and HNIW showed inconsistent dissolution behavior and congruent dissolution behavior in acetonitrile and ethyl acetate, respectively. In the HMX-HNIW-acetonitrile system, the 2HNIW·HMX cocrystal has a narrow thermodynamically stable region at both temperatures. The cocrystal exhibits a wider thermodynamically stable region in the HMX-HNIW-ethyl acetate system. The results show that the choice of solvent has a crucial influence on the dissolution behavior of the cocrystal and the size and position of each region in the phase diagram, while the temperature has no apparent effect on the overall appearance of the phase diagram. By properly selecting the ratios, the 2HNIW·HMX cocrystal could be prepared by the isothermal slurry conversion crystallization method.

4.
Molecules ; 25(15)2020 Jul 30.
Article de Anglais | MEDLINE | ID: mdl-32751631

RÉSUMÉ

Nitrated-pyrazole-based energetic compounds have attracted wide publicity in the field of energetic materials (EMs) due to their high heat of formation, high density, tailored thermal stability, and detonation performance. Many nitrated-pyrazole-based energetic compounds have been developed to meet the increasing demands of high power, low sensitivity, and eco-friendly environment, and they have good applications in explosives, propellants, and pyrotechnics. Continuous and growing efforts have been committed to promote the rapid development of nitrated-pyrazole-based EMs in the last decade, especially through large amounts of Chinese research. Some of the ultimate aims of nitrated-pyrazole-based materials are to develop potential candidates of castable explosives, explore novel insensitive high energy materials, search for low cost synthesis strategies, high efficiency, and green environmental protection, and further widen the applications of EMs. This review article aims to present the recent processes in the synthesis and physical and explosive performances of the nitrated-pyrazole-based Ems, including monopyrazoles with nitro, bispyrazoles with nitro, nitropyrazolo[4,3-c]pyrazoles, and their derivatives, and to comb the development trend of these compounds. This review intends to prompt fresh concepts for designing prominent high-performance nitropyrazole-based EMs.


Sujet(s)
Nitrates/composition chimique , Composés nitrés/composition chimique , Pyrazoles/composition chimique , Explosifs/synthèse chimique , Explosifs/composition chimique , Nitrates/synthèse chimique , Composés nitrés/synthèse chimique , Pyrazoles/synthèse chimique , Thermodynamique
5.
J Colloid Interface Sci ; 579: 733-740, 2020 Nov 01.
Article de Anglais | MEDLINE | ID: mdl-32673850

RÉSUMÉ

Transition metals and carbon materials are known as electromagnetic wave (EMW) nemesis, which can effectively attenuate EMW in the 2-18 GHz frequency band. Herein, three typical transition metal (Fe, Co, Ni) are freely combined into three layered double hydroxides (LDHs) through hydrothermal method and successfully grown in situ on the surface of short carbon fibers (SCFs). The SEM images show that although the three LDHs (CoNi-LDHs, FeNi-LDHs and FeCo-LDHs) are all sheet-like structures, their respective morphologies are completely different and each has its own merits. After calcination treatment at 500 °C, their distinct morphologies are basically retained, while the EMW absorption properties are greatly improved dramatically. Their effective absorption bandwidth (fe) (RL ≤ -10 dB) reached 3.68 GHz, 1.68 GHz and 4.48 GHz at thicknesses of 2.2 mm, 2.2 mm and 2.0 mm, respectively. As an important transition metal-based material, the exploration of LDHs in EMW absorption has just begun.

6.
J Colloid Interface Sci ; 574: 1-10, 2020 Aug 15.
Article de Anglais | MEDLINE | ID: mdl-32298976

RÉSUMÉ

At present, efficient and stable low-cost electromagnetic (EM) wave absorbing materials have been widely explored, but further improvement is still necessary. In this research, three types of hierarchical Co3O4/N-doped carbon/short carbon fiber (SCF) composites with different assembly structures were produced by annealing the ZIF-67/SCF and Co-LDHs/SCF precursors at 700 °C. The obtained Co3O4/N-doped carbon particles were uniformly attached on SCF in the form of nanocages or thin layer to compose a unique hierarchical structure. Notably, all three composites displayed high-performance EM wave absorption with a low filling ratio of only 20 wt% in paraffin matrix. Among them, cage-like Co-LDHs/SCF derived hierarchical carbon composite demonstrates the best performance, with a broad absorption bandwidth (RL ≤ -10 dB) of 6.08 GHz at 2.0 mm. Such excellent properties are attributed to the formed 3D conductive network, abundant Debye dipolar relaxation centers and strong interfacial polarization. These novel lightweight 2-methylimidazole-mediated Co3O4/N-doped carbon/SCF composites are expected to show great potential in EM wave absorption fields.

7.
ACS Omega ; 5(15): 8687-8696, 2020 Apr 21.
Article de Anglais | MEDLINE | ID: mdl-32337431

RÉSUMÉ

Dye-sensitized solar cells (DSSCs) are solar energy conversion devices with high efficiency and simple fabrication procedures. Developing transparent counter electrode (CE) materials for bifacial DSSCs can address the needs of window-type building-integrated photovoltaics (BIPVs). Herein, transparent organic-inorganic hybrid composite films of molybdenum disulfide and poly(3,4-ethylenedioxythiophene) (MoS2/PEDOT) are prepared to take full advantage of the conductivity and electrocatalytic ability of the two components. MoS2 is synthesized by hydrothermal method and spin-coated to form the MoS2 layer, and then PEDOT films are electrochemically polymerized on top of the MoS2 film to form the composite CEs. The DSSC with the optimized MoS2/PEDOT composite CE shows power conversion efficiency (PCE) of 7% under front illumination and 4.82% under back illumination. Compared with the DSSC made by the PEDOT CE and the Pt CE, the DSSC fabricated by the MoS2/PEDOT composite CE improves the PCE by 10.6% and 6.4% for front illumination, respectively. It proves that the transparent MoS2/PEDOT CE owes superior conductivity and catalytic properties, and it is an excellent candidate for bifacial DSSC in the application of BIPVs.

8.
J Nanosci Nanotechnol ; 20(5): 3140-3147, 2020 05 01.
Article de Anglais | MEDLINE | ID: mdl-31635658

RÉSUMÉ

Platinum (Pt) has been intensively studied as an effective cocatalyst for photocatalysis, but most reports have focused on metallic Pt rather than PtO. Here, Pt/PtO nanodots were deposited on porous yolk-shell La2O3 microspheres. XRD patterns and XPS analysis demonstrated the coexistence of Pt and PtO, which was beneficial for photocatalytic performance. SEM images showed the yolk-shell structure of La2O3, and TEM images demonstrated that the Pt/PtO nanodots were uniformly distributed on the La2O3 microspheres. The rate constant of the hybrid was calculated to be 0.00656 min-1 for methyl orange (MO) degradation, while that of bare La2O3 was only 0.00303 min-1. This work suggests that the use of the deposited cocatalyst Pt/PtO on La2O3 microspheres is a promising strategy for the degradation of organic pollutants.

9.
Nanomaterials (Basel) ; 10(1)2019 Dec 23.
Article de Anglais | MEDLINE | ID: mdl-31877983

RÉSUMÉ

The various volume concentrations of ionic liquid-modified graphene nanosheets filled polytetrafluoroethylene nanocomposites (IL-GNs/PTFE) for flexible conductors were fabricated via a pre-stretch processing method after cold-press sintering. The results indicated that pre-stretching has no significant weakening in the electrical conductivity of the nanocomposites, while the Young's modulus greatly reduced by 62.5%, which is more suitable for flexible conductors. This may be because the reduced conductivity by the destructive conductive pathway cancels out the enhanced conductivity by the increased interlamellar spacing of IL-GNs via a pre-stretch processing, and the nanocomposite exhibits a phase transition from two to three-phase (with the introduction of an air phase) during pre-stretching. It was also found that the tensile strength of the nanocomposites was enhanced by 42.9% and the elongation at break and thermal conductivity decreased slightly with the same filler content after pre-stretching. The electrical conductivity of the pre-stretched nanocomposites tended to stabilize at 5.5 × 10-2 s·m-1, when the volume content of the packings achieved a percolation threshold (1.49 vol%). Meanwhile, the electrical resistivity of the pre-stretched 3.0 vol% IL-GNs/PTFE nanocomposite was slightly reduced by 0.30%, 0.38%, and 0.87% respectively after 180° twisting, 180° bending, and 10% stretching strain for 1000 cycles.

10.
J Phys Chem B ; 113(35): 11898-905, 2009 Sep 03.
Article de Anglais | MEDLINE | ID: mdl-19678650

RÉSUMÉ

The effect of the polarity of modifier and polymer matrixes on the morphology and interfacial action of nanocomposites was studied by molecular dynamics (MD) and inverse gas chromatography (IGC) based on ethylene-vinyl acetate (EVA) /organic montmorillonite (OMMT), where vinyl acetate (VA) concentrations are 9.3 and 18 wt %, respectively. It is found that EVA with higher VA concentration displays a higher surface energy than that with lower VA concentration. Modifier with two long alkyl tails will lower the surface energy of montmorillonite (MMT) more effectively. Combined with transmission electron microscopy (TEM) photography of EVA/OMMT nanocomposites, it is found that the surface energies of organic montmorillonite and EVAs make great contributions to the dispersion of the OMMT in polymer matrixes. OMMT modified by two long alkyl tails displays weaker acid and base properties which will have a better interaction with EVAs through acid-base interaction. Molecular simulation (MD) proved that nonpolar interaction determines the binding between EVAs and organoclays, otherwise electrostatic interaction in polar polymer/organoclay systems. Binding energies were calculated by MD, and the results show stronger interaction between 20A (organoclay made from two long alkyl tails surfactant) and EVA. Interfacial action between filler and polymer matrix should be accountable for the mechanical properties of the nanocomposite.

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