Electrochemical water splitting enhancement by introducing mesoporous NiCoFe-trimetallic phosphide nanosheets as catalysts for the oxygen evolution reaction.

Transition metal-based catalysts are widely used in electrocatalysis, especially in the field of water splitting, due to their excellent electrochemical performance, which focuses on improving the efficiency of the complex oxygen evolution reaction (OER) that occurs at the anode. Transition metal-based catalysts will undergo electrochemical surface reconstruction and form (oxy)hydroxide-based hybrids, which consider the actual active sites for OER. So many efforts have been made to know the origin of the effect of electrochemical surface reconstruction on the performance of the OER. Herein, NiCoFe-phosphide catalyst nanosheets were constructed by a simple one-step hydrothermal reaction by adding oleylamine and ethanol to water solvent during the preparation of the catalyst precursor and high-temperature gas-phase phosphating and significantly showed high effectiveness catalytic activity and conductivity in comparison to normal and traditional preparation methods. Electrochemical analysis, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HRTEM) demonstrate that the surface was constructed during the electrochemical reaction and formed an amorphous layer of MOx(OH)y active sites, which increased the electrochemical surface area and promoted charge transfer. As well, the synthesized NiCoFePx-PNSs catalyst nanosheets exhibit excellent catalytic activity with a low overpotential equal to 259 mV to achieve the OER at a current density of 10 mA cm-2 and a low Tafel slope of 50.47 mV dec-1 which is better than for most reported transition metal-based electrocatalysts. This work provides a new design for a transition metal-based catalyst for OER as well as further insights into the effect of electrochemical surface reconstruction on intrinsic activity and OER performance.

Boosting oxygen evolution reaction rates with mesoporous Fe-doped MoCo-phosphide nanosheets.

Transition metal-based catalysts are commonly used for water electrolysis and cost-effective hydrogen fuel production due to their exceptional electrochemical performance, particularly in enhancing the efficiency of the oxygen evolution reaction (OER) at the anode. In this study, a novel approach was developed for the preparation of catalysts with abundant active sites and defects. The MoCoFe-phosphide catalyst nanosheets were synthesized using a simple one-step hydrothermal reaction and chemical vapor deposition-based phosphorization. The resulting MoCoFe-phosphide catalyst nanosheets displayed excellent electrical conductivity and a high number of electrochemically active sites, leading to high electrocatalytic activities and efficient kinetics for the OER. The MoCoFe-phosphide catalyst nanosheets demonstrated remarkable catalytic activity, achieving a low overpotential of only 250 mV to achieve the OER at a current density of 10 mA cm-2. The catalyst also exhibited a low Tafel slope of 43.38 mV dec-1 and maintained high stability for OER in alkaline media, surpassing the performance of most other transition metal-based electrocatalysts. The outstanding OER performance can be attributed to the effects of Mo and Fe, which modulate the electronic properties and structures of CoP. The results showed a surface with abundant defects and active sites with a higher proportion of Co2+ active sites, a larger specific surface area, and improved interfacial charge transfer. X-ray photoelectron spectroscopy (XPS) analysis revealed that the catalyst's high activity originates from the presence of Mo6+/Mo4+ and Co2+/Co3+ redox couples, as well as the formation of active metal (oxy)hydroxide species on its surface.

A novel energetic cocrystal composed of CL-20 and 1-methyl-2,4,5-trinitroimidazole with high energy and low sensitivity.

A cocrystal explosive comprising 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) and 1-methyl-2,4,5-trinitroimidazole (MTNI) (molar ratio, 1:1) was synthesized. The structure of the cocrystal was characterized by single-crystal X-ray diffraction. Its structure was further determined by powder X-ray diffraction, infrared spectroscopy and differential scanning calorimetry which showed that its morphology was different from the morphology of the mechanical mixture of two raw materials. The decomposition temperature of the cocrystal is lower than that of CL-20 and MTNI. The calculated detonation performance is slightly lower than that of HMX, but the cocrystal has excellent sensitivity performance relative to that of CL-20, even lower than that of RDX. These features make this cocrystal ideal to be used in applications with low-sensitivity requirements.

Preparation and characteristics of a novel PETN/TKX-50 co-crystal by a solvent/non-solvent method.

In order to decrease the sensitivity and broaden the application of pentaerythritol tetranitrate (PETN), a novel energetic co-crystal composed of PETN and dihydroxylammonium 5,5'-bistetrazole-1,1'-diolate (TKX-50) with high energy and low sensitivity was successfully prepared through the solvent/non-solvent method. The morphology and structure of the as-prepared co-crystal were characterized by scanning electron microscopy (SEM), X-ray diffraction spectroscopy (XRD), X-ray photoelectron spectrometry (XPS), fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy and high performance liquid chromatography (HPLC). The thermal decomposition properties were also analyzed by simultaneous thermogravimetry and differential scanning calorimetry (TG-DSC). The safety performance was judged by mechanical sensitivity tests. The SEM results revealed that the prepared new material was homogeneous with a mean granularity of 1 µm and the morphology was distinct from raw PETN and TKX-50. The XRD analysis indicated that a new crystalline formation appeared in the co-crystal which was quite different from the raw materials and their mixture. The XPS analysis showed peak shifts of C, N, O elements in the co-crystal. The FTIR spectra and Raman spectra suggested that hydrogen bond interactions existed between PETN and TKX-50 molecules. The molar ratio of PETN and TKX-50 was 1 : 1 determined by HPLC. There were two thermal decomposition peaks (194.1 °C and 261.3 °C) for the co-crystal at 20 °C min-1, while the raw materials and mixture had only one. Besides, the activation energy of the co-crystal increased compared to the raw materials, indicating better thermal stability of the co-crystal. The impact sensitivity and friction sensitivity of the PETN/TKX-50 co-crystal were reduced compared to raw PETN, and were even better than for 1,3,5-trimethylene trinitramine (RDX). The results showed a prospective application of the prepared PETN/TKX-50 co-crystal in the future.

Acute toxicity assessment of explosive-contaminated soil extracting solution by luminescent bacteria assays.

Explosive-contaminated soil is harmful to people's health and the local ecosystem. The acute toxicity of its extracting solution was tested by bacterial luminescence assay using three kinds of luminescent bacteria to characterize the toxicity of the soil. An orthogonal test L 16 (45) was designed to optimize the soil extracting conditions. The optimum extracting conditions were obtained when the ultrasonic extraction time, ultrasonic extraction temperature, and the extraction repeat times were 6 h, 40 °C, and three, respectively. Fourier transform infrared spectroscopy (FTIR) results showed that the main components of the contaminated soil's extracting solution were 2,4-dinitrotoluene-3-sulfonate (2,4-DNT-3-SO3-); 2,4-dinitrotoluene-5-sulfonate (2,4-DNT-5-SO3-); and 2,6-dinitrotoluene (2,6-DNT). Compared with Photobacterium phosphoreum and Vibrio fischeri, Vibrio qinghaiensis sp. Nov. is more suitable for assessing the soil extracting solution's acute toxicity. Soil washing can remove most of the contaminants toxic to luminescent bacterium Vibrio qinghaiensis sp. Nov., suggesting that it may be a potential effective remediation method for explosive-contaminated soil.

Treatment of soil eluate containing nitro aromatic compounds by adsorption on activated coke (AC).

Soil washing is a kind of physical method to remove organic matters from contaminated soil. However, its eluate after washing may result in secondary pollution to the environment. In this study, activated coke (AC) was used to remove organic pollutants from contaminated soil eluate. The effect of temperature, initial chemical oxygen demand (COD) and AC dosage on COD removal efficiency was investigated. The results showed that the organic matter can be removed in the eluate because the COD dropped a lot. When the AC dosage was 20 g·L(-1), 88.92% of COD decreased after 480 min of adsorption at 50 °C. The process of adsorption can be described by the Redlich-Peterson isotherm. The adsorption was spontaneous and endothermic. The pseudo-second-order model can be used to describe the adsorption process. After adsorption, the acute toxicity of the eluate was reduced by 76%, and the water qualities were in agreement with Chinese discharge standard GB 14470.1-2002, which means the eluate could be discharged to the environment.

[Reversed changes of the 15-lipoxygenase product lipoxin A4 and the 5-lipoxygenase product leukotriene C4 in children with asthma].

OBJECTIVE: To investigate the expressions of 15- and 5-lipoxygenases in leukocytes and the changes of the levels of blood lipoxin A4 (LXA4) and leukotriene C4 (LTC4) in children with asthma. METHODS: The mRNA levels of 15- and 5-lipoxygenases in leukocytes were assessed by RT-PCR, and the levels of blood LXA4 and LTC4 were determined by ELISA, in 106 children with mild, moderate and severe asthma. Forty healthy children served as the controls. RESULTS: In children with mild, moderate and severe asthma, the relative mRNA levels of 15-lipoxygenase in leukocytes were 1.78 ± 0.56, 1.28 ± 0.45 and 0.58 ± 0.22 (F = 16.72, P < 0.01), respectively, and all were higher than that of the controls (0.26 ± 0.12, P < 0.05). The levels of blood LXA4 were (5.52 ± 1.97), (1.86 ± 0.72) and (0.81 ± 0.36) µg/L (F = 22.59, P < 0.01), respectively, decreasing with the severity of asthma, and all were higher than that of the controls [(0.04 ± 0.01) µg/L, P < 0.05]. There was a positive correlation between PEF, FEV(1) and blood LXA4. The relative levels of 5-lipoxygenase mRNA in leukocytes were 0.26 ± 0.12, 0.79 ± 0.34 and 1.21 ± 0.52, respectively in children with asthma of mild, moderate and severe degree (F = 18.64, P < 0.01), which showed an increase with the severity of the disease, and all of which were higher than that of the controls (0.12 ± 0.05, P < 0.05). The levels of blood LTC4 were (22.4 ± 8.2), (54.6 ± 28.4) and (118.7 ± 41.1) ng/L (F = 25.91, P < 0.01), respectively, also showing an increase with the severity of asthma, and were higher than that of the controls [(6.8 ± 2.5) ng/L, P < 0.05]. There was a negative correlation between PEF, FEV1 and blood LTC4. CONCLUSION: The reversed changes of 15-lipoxygenase product LXA4 and 5-lipoxygenase product LTC4 in children with asthma of mild, moderate and severe degree suggests that insufficiency of LXA4, an physiological antagonist to leukotrienes, and an overproduction of LTC4, may be involved in the pathogenesis of worsening of asthma in children.