Hexagonal FeS nanosheets with high-energy (001) facets: Counter electrode materials superior to platinum for dye-sensitized solar cells

The catalytic activity of materials is highly dependent on their composition and surface structure, especially the density of low-coordinated surface atoms. In this work, we have prepared two-dimensional hexagonal FeS with high-energy (001) facets (FeS-HE-001) via a solution-phase chemical method. Nanosheets (NSs) with exposed high-energy planes usually possess better reaction activity, so FeS-HE-001 was used as a counter electrode (CE) material for dye-sensitized solar cells (DSSCs). FeS-HE-001 achieved an average power conversion efficiency (PCE) of 8.88% (with the PCE of champion cells being 9.10%), which was almost 1.15 times higher than that of the Pt-based DSSCs (7.73%) measured in parallel. Cyclic voltammetry and Tafel polarization measurements revealed the excellent electrocatalytic activities of FeS-HE-001 towards the I ₃ ^– /I^– redox reaction. This can be attributed to the promotion of photoelectron transfer, which was measured by electrochemical impedance spectroscopy and scanning Kelvin probe, and the strong I ₃ ^– adsorption and reduction activities, which were investigated using first-principles calculations. The presence of high-energy (001) facets in the NSs was an important factor for improving the catalytic reduction of I ₃ ^– . We believe that our method is a promising way for the design and synthesis of advanced CE materials for energy harvesting.

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Epitaxial layers of CuInSe2

Epitaxial layers of CuInSe₂ and related mixed crystals were grown on different substrates by liquid phase epitaxy and molecular beam epitaxy but mainly by flash evaporation. The geometrical foundations and experimental results are discussed. The type of epitaxy (one-dimensional, multiple orientation or unique) the epitaxial temperature range and particularly the epitaxial relationships are described.     

Soluble polypyrrole as the transparent anode in polymer light-emitting diodes

Polypyrrole (PPy) films processed from solution have been used as semi-transparent anodes in polymer light-emitting diodes. An external quantum efficiency of 0.5% was achieved with poly (2-methoxy,5-(2′-ethyl-hexyloxy)-1,4-phenylene-vinylene) (MEH—PPV) as the luminescent polymer. The hole-injection potential barrier between PPy and MEH—PPV, as determined by Fowler—Nordheim analysis, is≈ 0.23 eV.     

Further studies of the formation of filamentous carbon from the interaction of supported iron particles with acetylene

A combination of controlled atmosphere electron microscopy and Mössbauer spectroscopy has been used to investigate the characteristics of supported α-iron and γ-iron particles during the formation of carbon filaments via decomposition of acetylene. γ-iron was found to exhibit a higher intrinsic activity than α-iron for this reaction when the metal was supported on graphite. In both systems, however, catalytic action decreased significantly at temperatures in excess of 700°C. Major changes were observed in the catalytic behavior of the metal particles when they were supported on silica. The rate of formation of carbon filaments from the α-iron/silica system showed a uniform increase up to 900°C. Mössbauer spectroscopy analysis of similarly treated samples revealed that under these conditions α-iron was the only metallic phase present, even though experiments were conducted through a temperature region where the transformation of α-iron to γ-iron can occur, suggesting that silica stabilizes the α-form of iron. In contrast, the catalytic activity displayed by γ-iron particles supported on silica was considerably reduced over that found for the corresponding graphite supported system. The results of this study are discussed in terms of some of the factors controlling the growth characteristics of filamentous carbon.     

Structures and Metal Leachability of Sintered Sludge-Clay Ceramsite Affected by Raw Material Basicity

To solve the disposal problem of wastewater treatment sludge (WWTS), WWTS was mixed with clay and water glass (sodium silicate) for the production of lightweight ceramsite. The effect of mass ratio of CaO/SiO2 (defined as basicity) on physicochemical characteristics of ceramsite and stabilization of heavy metals was investigated. It was found that the optimal basicity for making ceramsite ranges was 0.024–0.069. The main thermal changes ( ≤ 1,000??°C) are phase transformations, which are caused by the evaporation and volatilization of water and carbonous matters and, finally, by the oxidation and decomposition of inorganic matters and minerals. Anorthite [Ca(Al2Si2O8)] and amorphous silica (SiO2) increase as the basicity increases. The formation of more multiple crystalline phases is the main reason for the decrease in the compressive strength of the ceramsite with higher basicity. Leaching contents of Cd, Cu, Cr, and Pb decrease as the basicity increases. The stable compounds of heavy metals in ceramsite are PbCrO4, Cr2O3, CdSiO3, and CuO, which prove that strong chemical bonds are formed and the leachability of these heavy metals is greatly reduced by the crystallization and chemical incorporation process. Results indicate that basicity can be used as an important parameter for controlling the properties of ceramsite.     

Tensile strength and fiber/matrix interfacial properties of 2D- and 3D-carbon/carbon composites

The tensile and fiber/matrix interfacial properties of 2D and 3D carbon/carbon composites (C/C) were compared. To elucidate the effect of three-dimensional reinforcement, both C/Cs were composed of the same constituents and prepared via. the same process route. The tensile fracture strain of both C/Cs degraded with increasing bulk density, and the fracture strain of the 3D-C/Cs were larger than that of the 2D-C/Cs at the same bulk density. The interfacial bonding strength of the 3D-C/Cs were found to be much lower than that of the 2D-C/Cs. From the comparison of the interfacial and tensile fracture behavior, high tensile fracture strains of 3D-C/Cs were concluded to be attributed to the weak interfacial bonding. This low interfacial strength of the 3D-C/Cs was suggested to be caused by the residual stresses induced during processing in the 3D-C/Cs due to three-dimensional restriction of the fibers.     

应用型本科院校实习实训的开展模式及实施措施

随着科学技术的进步,我国综合国力得到了进一步发展,但由于教育体制、人才培养模式等诸多方面原因的限制,目前高等教育所培养出的人才仍然存在较多不足,面对国家经济发展转型升级及提升国际间竞争力的紧迫要求,急需培养一大批动手能力强、综合素质高的卓越人才.高校的实习实训课程是学生获取生产实践技术,巩固理论知识的有效措施,也是培养学生工程实践能力、独立工作能力、运用所学知识分析和解决生产实际问题的重要环节,对于应用型本科院校尤为重要.以应用型本科院校黑龙江工程学院为例,从其实习实训的现状出发,分析国内外实习、实训的主要模式,提出以“共赢”为原则,以“项目驱动”为牵引的校企合作模式,并探讨相应的保障实施措施.     

Mg-8Li-3Al合金中稀土Y微合金化对显微组织的影响

采用真空感应熔炼技术制备Mg-8Li-3Al-xY合金。研究添加不同含量稀土Y对Mg-8Li-3Al合金组织的影响。结果表明：在Mg-8Li-3Al合金中加入稀土Y后,a（Mg）相被明显细化和球化,随着Y含量增加,合金中生成Al2Y稀土化合物。     

氧化铁催化尿素醇解制备碳酸二甲酯反应工艺的研究

通过固体研磨法、溶胶一凝胶法、沉淀法和铁盐强迫水解法制备得到4种氧化铁催化剂,并对其进行尿素与甲醇反应制碳酸二甲酯(DMC)活性测定。结果表明,沉淀法制备的氧化铁催化剂的催化效果更好,并得出合成碳酸二甲酯反应的最佳工艺条件为:n(甲醇):n(尿素)=65,每68mL甲醇催化剂用量0.1g,反应温度180℃,反应时间7h。探讨由纳米氧化铁催化尿素醇解法合成DMC的反应机理,是由具有Lewis酸性的氧化铁共同活化甲醇和尿素的结果。     

不同靶基距下凹槽表面HIPIMS法制备钒膜的微观结构及膜厚均匀性

目的研究不同靶基距对高功率脉冲磁控溅射(HIPIMS)在凹槽表面制备钒膜微观结构和膜厚均匀性的影响,实现凹槽表面高膜层致密性和均匀性的钒膜制备。方法采用HIPIMS方法制备钒膜,在其他工艺参数不变的前提下,探讨不同靶基距对凹槽表面钒膜相结构、表面形貌及表面粗糙度、膜层厚度均匀性的影响。采用XRD、AFM及SEM等观测钒膜的表面形貌及生长特征。结果随着靶基距的增加,V(111)晶面衍射峰强度逐渐降低。当靶基距为12 cm时,钒膜膜层表面粗糙度最小,为0.434nm。相比直流磁控溅射(DCMS),采用HIPIMS制备的钒膜呈现出致密的膜层结构且柱状晶晶界不清晰。采用HIPIMS和DCMS方法制备钒膜时的沉积速率均随靶基距的增加而减少。当靶基距为8 cm时,采用HIPIMS方法在凹槽表面制备的钒膜均匀性最佳。结论采用HIPIMS方法凹槽表面钒膜生长的择优取向、表面形貌、沉积速率及膜厚均匀性均有影响。在相同的靶基距下,采用HIPIMS获得的钒膜膜厚均匀性优于DCMS方法。