Effect of mesoporous ZSM-5 morphology on the catalytic performance of cobalt catalyst for Fischer-Tropsch synthesis

Mesoporous ZSM-5 with various morphologies loading cobalt were prepared and applied in Fischer-Tropsch synthesis. Smaller ZSM-5 particles showed higher intensity of strong acid sites resulting in higher cobalt-support interaction. The activity and CH₄ selectivity were remarkably related with cobalt-support interaction over such acidic supports. Cobalt loaded on spindle mesoporous ZSM-5 exhibited the lowest activity and the highest CH₄ selectivity due to the strongest cobalt-support interaction, but the highest activity was obtained over cubic mesoporous ZSM-5 with the lowest cobalt-support interaction originating from weaker acid sites. In addition, adjusting acid intensity and mesopore volumes could successfully tuned hydrocarbon distribution. Spherical ZSM-5 with hierarchical structure containing larger mesopore volumes and moderate acid intensity effectively promoted the production of C₁₂-₁₈ hydrocarbons. The highest C₅-₁₁ selectivity was observed over cobalt supported on hexagonal meso-ZSM-5 due to the enhancement in diffusion limitation over lower mesopore volumes and hydrocracking of primary hydrocarbons over higher Brønsted acid sites.     

Influence of ball milling duration on the morphology,features of the structural-phase state and microhardness of 3Ni-Al powder mixture

The features of changes in the morphology, structural-phase state and microhardness of 3Ni-Al powder mixture after different duration of high-energy ball-milling have been studied. Three main stages of the evolution of the structural-phase state were revealed, which, corresponding to different duration of treatment, differ in the morphology of the powder mixture, distribution of components, phase compositions and the nature of changes in microhardness. It was found that under high-energy ball-milling conditions, the synthesis of intermetallic Ni₃Al and NiAl phases begins at much lower temperatures compared to the phase diagram. It is shown that an increase in the duration of high-energy ball-milling is accompanied by a transformation of the phase composition, the features of which determine the level of strengthening of the powder mixture studied.     

Role of morphology in electrochemical hydrogen storage using binary DyFeO3-ZnO nanocomposites as electrode materials

Hydrogen storage technology is one of the most challenging issues due to the increasing demand for fossil fuel replacement and the reduction of greenhouse gas emissions. In the current paper, the main aim is one-step and eco-friendly preparation of DyFeO₃-ZnO nanocomposites using Barberry fruit extract as natural precursor (with the role of both fuel and capping agent) to compare with various conventional carboxylic acids. To further examine, the effect of different parameters like calcination temperature and the type of the chelating agent was scrutinized to acquire optimum shape, structure, morphology and size of the obtained products. This is the first effort on the investigation of the hydrogen storage capacity of DyFeO₃-ZnO nanocomposites in terms of role of morphology. The electrochemical hydrogen storage capacity of obtained DyFeO₃-ZnO nanocomposites was studied mediated by chronopotentiometry charge-discharge methods in KOH medium. The synthesis of nanocomposites in the presence of chemical or natural capping agent (carboxylic acids or Barberry fruit extract) led to different morphologies which affects to the electrochemical performance. As a result, the electrode which is provided by plate-like DyFeO₃-ZnO nanocomposites performed 600.11 mAh/g discharge capacity compared with other samples. Based on the obtained results, DyFeO₃-ZnO nanocomposites can be promising compounds to improve the electrochemical performance of hydrogen storage.     

Synthesis and characterization of cross-linked polymer with sulfonylimide group via UV-radical polymerization for PEMFC

The purpose of this research is to synthesized a new monomer and polymer containing fluorosulfonyl imide acid. A series of polymer electrolyte membranes are prepared via UV-curing technique with polyethylene glycol dimethacrylate (PEGDMA) and the methacryloyl fluorosulfonylimide (MAFSI), which is synthesized by methacrylamide (MAA) and fluorosulfonyl isocyanate (FSO₂NCO). The MAFSI monomer and the polymer electrolyte (PMFP) are successfully synthesized and confirmed the structure by ¹H NMR and FT-IR. The membranes exhibit high proton conductivity from 79.14 to 110.87 mS/cm, low water uptake from 8.74 to 28.57%, and low dimensional expansion from 6.5 to 30.8% in spite of high IEC values from 3.97 to 5.71 meq./g. In addition, the membranes exhibit good thermal stability up to 150 °C temperatures and the surface morphology of the membrane observed good phase separation between MAFSI and ethylene glycol segments.     

Spatiotemporal mapping of microscopic strains and defects to reveal Li-dendrite-induced failure in all-solid-state batteries

Solid-state electrolytes (SSEs) are key to the success and reliability of all-solid-state lithium batteries, potentially enabling improvements in terms of safety and energy density over state-of-the-art lithium-ion batteries. However, there are several critical challenges to their implementation, including the interfacial instability stemming from the dynamic interaction of as-formed dendritic lithium during cycling. For this work, we emphasize the importance of studying the spatial distribution and temporal evolution of strains and defects in crystalline solid-state electrolytes at the micro-scale, and how this affects dendrite growth. A proof-of-principle study is demonstrated using the synchrotron radiation based micro Laue X-ray diffraction method, and a custom-developed in-situ cycling device. Defects and residual strains are mapped, and the evolution of intragranular misorientation is observed. The feasibility of using this technique is discussed, and recommendations for micro-strain engineering to address the Li/SSEs interfacial issues are given. Also, work directions are pointed out with the consideration of combining multi-techniques for “poly-therapy”.     

Electrosynthesis of dendritic palladium supported on Ti/TiO2NTs/Ni/CeO2 as high-performing and stable anode electrocatalyst for methanol electrooxidation

Liquid-fueled direct methanol fuel cell (DMFC) is highly promising for low-carbon transportation, but is hindered by high cost and short lifespan of conventional Pt-based electrocatalysts. Herein, we propose a new Pt-free catalyst strategy to exploit high-performing and stable electrocatalyst of DMFC, achieving enhanced electrocatalytic activity and high stability for methanol oxidation reaction (MOR) in alkaline media. A new Pt-free anode catalysts consisting of titanium/reduced-titanium dioxide nanotubes/nickel/cerium dioxide (Ti/r-TiO₂NTs/Ni/CeO₂) nanosupport and uniformly-dispersed Pd dendrites is successfully prepared by a facile three-step electrodeposition route without applying any template or surfactant. Noticeably, the as-prepared Ti/r-TiO₂NTs/Ni/CeO₂–Pd as an anode electrode exhibits superior activity than commercial Pd/C and other electrodes. The obtained large mass activity for Ti/r-TiO₂NTs/Ni/CeO₂–Pd electrode is 1752 mA mg_Pd^?1 for MOR. After successive CV tests of 1000 cycles, Ti/r-TiO₂NTs/Ni/CeO₂–Pd electrode still retained 88.9% of its initial current. The superior performance of Ti/r-TiO₂NTs/Ni/CeO₂–Pd attributes to the large surface area and excellent conductivity, as well as the synergistic effects among nanosupport and Pd dendrites. Therefore, this study will open a new door for high-performance fuel cell applications.     

Biomass-derived carbon nanosheets coupled with MoO2/Mo2C electrocatalyst for hydrogen evolution reaction

Transition metal carbide such as molybdenum carbide has been widely used in electrolytic water for hydrogen production due to its potential catalytic property. The synthesis of molybdenum carbide-based high-efficient catalysts by simple process remains great challenges. Herein, Mo oxide/carbide material with hybrid morphology was synthesized by carbonizing mixture of lotus roots and Mo salt. The as-obtained material consists of MoO₂/Mo₂C (MOMC) anchored on biomass-derived nitrogen-doped carbon (NC) matrix. The results show that as-prepared material displays leaf-like and belt-like nanosheets, and the MOMC/NC catalyst with optimal Mo contents exhibits an excellent activity with a low overpotential of 138 mV to drive 10 mA cm^?2 and Tafel slope is 56.7 mV dec^?1 in alkaline medium, indicating that as-prepared catalyst will have promising application in the field of catalysis.     

贵州某电厂灰场的岩溶渗漏研究和治理

灰场的岩溶渗漏问题是岩溶地区电厂岩土工程勘测中的主要问题．本文通过某电厂的勘测为例来研究该问题。并提出一些相应的治理方法。     

空间句法：从图论的角度看中微观城市形态

如何从整体的角度研究城市形态的复杂性？空间句法在城市形态领域中关注城市形态空间之间的整体联系，运用图论的数学理论和方法建立了城市形态的模型，发现了不同城市具有相似的城市空间拓扑关系，以及特定城市空间之间复杂的整体关联在很大程度上决定了中微观层面的人车流和用地的分布，给城市形态复杂性研究提供了坚实可行的理论基础和方法程序、也给整合交通规划和用地规划的城市规划和设计提供了一种具体的实践角度。本文简要回顾了城市形态研究中关于要素和关联的研究发展、详细解释了空间句法从图论的角度研究城市形态的整体关联，最后分析了空间句法在伯明翰Brindleypalce案例中的应用。