Properties and application of lead–calcium–tin–aluminium–bismuth alloys for positive grids

The effects of bismuth addition less than 0.05 wt% on the electrochemical properties of lead–calcium–tin–aluminum alloys were investigated in detail. Passivation and corrosion phenomena were investigated by cyclic voltammetry, electrochemical impedance spectra, linear sweep voltammetry. The effect of bismuth on oxygen evolution and hydrogen evolution were also discussed. The experimental results show that the addition of bismuth leads to the decreases of the hydrogen overpotential and increase of the hydrogen evolution rate. Oxygen evolution rate increases with the increase of content of bismuth. The measurements of cyclic voltammetry suggested that bismuth may promote the formation of lead dioxide. A key result was that the presence of bismuth might have beneficial effect on the formation of Pb(II).     

Fracture toughness improvement of epoxy resins with short carbon fibers

This study examined the thermal stability and fracture toughness of diglycidylether of bisphenol-A (DGEBA)/short carbon fiber (SCF) composites using several techniques. The thermal stability of the DGEBA/SCF composites was similar to that of neat epoxy resin. The fracture toughness of the composites was significantly improved relative to the neat resin. The SEM micrographs indicated that a relatively rough surface with shear deformation and tortuous cracks was formed, thereby preventing deformation and crack propagation and inducing higher fracture toughness in the DGEBA/SCF composites.     

Steam reforming of n-dodecane over mesoporous alumina supported nickel catalysts: Effects of metal-support interaction on nickel catalysts

Developing a highly active and stable Ni-based catalyst is still a challenge for the generation of on-site hydrogen through steam reforming of long-chained hydrocarbons, such as kerosene fuels. Ni nanoparticles (ca. 5 nm) on mesoporous alumina prepared by atomic layer deposition (ALD) were employed in steam reforming of n-dodecane, and exhibited a turnover frequency (TOF) of 477.6 h⁻¹, whereas Ni nanoparticles on commercial alumina support prepared by impregnation method exhibited a TOF of 100 h⁻¹. The high activity of ALD Ni catalysts was ascribed to high reduction degree, as confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM), and H₂-chemisorption. A deactivation was also observed on the ALD prepared catalysts, which was ascribed to the weak metal-support interaction, as confirmed by H₂ temperature-programmed reduction (TPR). The ALD Ni/Al₂O₃ catalysts were further modified with CeO₂ and they showed enhanced stability with 8% deactivation degree in steam reforming of n-dodecane. Further characterizations of spent catalysts showed that the presence of CeO₂ was favorable for stabilizing Ni nanoparticles by enhancing moderate metal-support interaction, and reducing the formation of coke on the interfaces of NiCeO₂.     

Trace sulfur promoted Fe,N-codoped carbon black as electrocatalyst for oxygen reduction reaction

Doping carbon materials with Fe and N attracts great attention due to its promising application in preparing ORR electrode with high performance and low cost. Previously, Fe, N-codoped catalyst (Fe/N/C) had been synthesized via a simple one-pot method using carbon materials, dopamine and FeCl₃ by our group. However, the unstable activity and low selectivity (electron transfer number of ∼3.5) are key problems that should be solved. Herein, trace sulfur has been introduced into Fe, N-codoped carbon black by using 2-mercaptoethanol as an adhesive sulfur precursor. By the doping of trace S atoms (∼0.25 at%) into Fe, N-codoped carbon frameworks, the ORR performance has been obviously improved simply without any re-treatment process, such as acid-etching or nitrogen supplement. The mechanism of this process has been systematically investigated by changing the amount of initial sulfur precursor. A moderate amount of trace sulfur can effectively enhance the ORR performance of Fe, N-codoped carbon black due to suitable interactions among Fe, N, S and C elements. Both the content and the state of Fe and N species on the surface of carbon black can be changed and controlled by trace sulfur. The as-synthesized 1.0 SFe/N/C catalyst exhibits a good ORR activity (E_1/2 = 0.749 V, J_k = 54.56 mA cm⁻²) and a total 4-electron selectivity. 1.0 SFe/N/C also shows better catalytic stability and methanol tolerance than 20 wt% Pt/C.     

Morphology effect of MnO2 promoter to the catalytic performance of Pt toward methanol electrooxidation reaction

Three MnO₂ samples with different well-defined morphologies including nanoplates, nanorods and corallines are prepared through a simple chemical precipitation method and used as the promoter/support for Pt electrocatalysts (denoted as Pt/MnO₂P, Pt/MnO₂-R and Pt/MnO₂C, respectively). The morphology effects of MnO₂ to the catalytic properties of Pt for methanol oxidation reaction (MOR) are intensively investigated. Results show that the catalytic properties of Pt are strongly dependent on the morphology of the promoter. Pt/MnO₂-R with MnO₂ nanorods as the promoter shows the highest catalytic properties among the MnO₂-promoted catalysts. The mass-specific activity and intrinsic activity of Pt in Pt/MnO₂-R catalyst is 0.51 A mg⁻¹_Pt and 11.54 A m⁻²_Pt, which is ca. 1.89 and 2.18 times that of commercial Pt/C catalysts (0.27 A mg⁻¹_Pt and 5.29 A m⁻²_Pt), respectively. Change in the electronic structure of Pt is responsible for the enhancement in the catalytic properties of Pt/MnO₂-R.     

Surface destruction and performance reduction of the ZnO nanowire arrays electrode in dye sensitization process

ZnO based dye-sensitized solar cells have been widely investigated. The limitation of the conversion efficiency is studied in this work. Obvious morphology changes of the ZnO nanowire electrode occur after a period of time sensitized in the ruthenium N719 dye ethanol solution. The surface dissolution of the ZnO nanowires and the formation of Zn²⁺/dye aggregates have been discovered and characterized. The influence of the sensitization duration on the cell performance is investigated and discussed. The short circuit current density and overall conversion efficiencies of the cells decrease extremely when the sensitization time is prolonged. The results exhibit that ruthenium N719 dye is not suitable enough to the ZnO nanowire arrays electrode.     

Development of PVA based micro-porous polymer electrolyte by a novel preferential polymer dissolution process

A micro-porous polymer electrolyte based on PVA was obtained from PVA–PVC based polymer blend film by a novel preferential polymer dissolution technique. The ionic conductivity of micro-porous polymer electrolyte increases with increase in the removal of PVC content. Finally, the effect of variation of lithium salt concentration is studied for micro-porous polymer electrolyte of high ionic conductivity composition. The ionic conductivity of the micro-porous polymer electrolyte is measured in the temperature range of 301–351 K. It is observed that a 2 M LiClO₄ solution of micro-porous polymer electrolyte has high ionic conductivity of 1.5055 × 10⁻³ S cm⁻¹ at ambient temperature. Complexation and surface morphology of the micro-porous polymer electrolytes are studied by X-ray diffraction and SEM analysis. TG/DTA analysis informs that the micro-porous polymer electrolyte is thermally stable upto 277.9 °C. Chronoamperommetry and linear sweep voltammetry studies were made to find out lithium transference number and stability of micro-porous polymer electrolyte membrane, respectively. Cyclic voltammetry study was performed for carbon/micro-porous polymer electrolyte/LiMn₂O₄ cell to reveal the compatibility and electrochemical stability between electrode materials.     

Hydrogen production via CO2 dry reforming of glycerol over ReNi/CaO catalysts

The present work investigates the performance of Re-promoted Nickel-based catalyst supported on calcium oxide for glycerol dry reforming reaction. The catalysts were prepared using wet impregnation method and their catalytic performance was tested in a packed bed reactor with CO₂ to glycerol ratio (CGR) of 1–5, reaction temperature of 600–900 °C and gas hourly specific velocity (GHSV) of 1.44 × 10⁴–7.20 × 10⁴ ml g_cat⁻¹ s⁻¹. The optimum operating temperature for both Ni/CaO and ReNi/CaO is 800 °C, with the GHSV of 3.6 × 10⁴ mL g_cat⁻¹s⁻¹. The optimum CGR for Ni/CaO and ReNi/CaO is 1.0 and 3.0, respectively. At this condition, hydrogen gas is directly produced from glycerol decomposition and indirectly from water-gas-shift reaction. After 2 h at the optimum conditions, 5% ReNi/CaO gives optimal glycerol conversion and hydrogen yield of approximately 61% and 56%, respectively, while in comparison to 15% Ni/CaO, the conversion and yield are 35 and 30%, respectively. Characterization of the spent catalysts showed the existence of whisker carbon from the CO₂ hydrogenation and methanation processes. By comparing to 15% Ni/CaO, the addition of Re increases the acidic sites of the catalyst and enhanced the surface adsorption of OH group of the glycerol. The adsorbed glycerol on the catalyst surface would further react with the adsorbed CO₂ to yield gases products. Thus, the catalytic activity improved significantly.     

An address mapping approach for test data generation of dynamic linked structures

Software testing is an important technique to assure the correctness of the software. One of the essential prerequisite tasks of software testing is test data generation. This paper proposes an approach to generate test data specifically for dynamic pointer structures. In our context, a pointer is considered and handled as a location in memory, represented by a dynamic linear array that expands and shrinks during execution. As such, pointer test data can be directly generated from this linear array. The proposed technique can also support any dynamic structures, as well as homogeneous and heterogeneous recursive structures.     

Mechanochemical synthesis of hybrid electrolytes from the Li2S–P2S5 glasses and polyethers

Novel hybrid solid electrolytes were prepared by mechanochemistry using the Li⁺ conductive Li₂S–P₂S₅ glasses and –OH terminated oligomers. The P–O–C bonds were observed in FT-IR spectra for the obtained electrolytes, suggesting that the molecular level hybrid materials were synthesized. The addition of small amounts of oligomers into the glass successfully enhanced the conductivity of hybrid electrolytes by lowering glass transition temperature. The hybrid electrolyte with 2 mol% of 1,4-butanediol exhibited the ambient temperature conductivity of 9.7 × 10⁻⁵ S cm⁻¹, which is 1.5 times as large as the conductivity of the pristine glass. The hybrid with a polyether showed lower conductivity than the hybrid with 1,4-butanediol. Incorporating oligomer blocks into glass network is a new approach to enhance the conductivity of glass-based solid electrolytes.