Surfactant-assisted synthesis of reduced graphene oxide/polyaniline composites by gamma irradiation for supercapacitors

A series of graphene materials are prepared by intercalation of graphene oxide (GO) with different surfactants, cetyltrimethylammonium bromide (CTAB), n-octyltrimethylammonium bromide, tetramethylammonium bromide, and sodium dodecylbenzene sulfonate, subsequently by γ-ray induced reduction in N-methyl-2-pyrrolidone (NMP) at room temperature. GO can be reduced by the electrons generated from the radiolysis of NMP under γ-ray irradiation, and reduced GO is simultaneously functionalized by the radiolytic product of NMP. Cationic surfactant CTAB with longer alkyl chains can effectively promote the reduction process of GO by preventing the aggregation of graphene sheets, which has been testified by X-ray photoelectron spectroscopy, X-ray diffraction, thermogravimetric analysis, Raman spectroscopy, and Fourier transform infrared spectroscopy analyses. Furthermore, when the as-prepared graphene/polyaniline composites are used for supercapacitor electrode materials, there is a highest specific capacitance of 484 F g^?1 at a current density of 0.1 A g^?1 for the graphene produced in the presence of cationic surfactant CTAB.     

Ultrasmall Fe3O4 Nanoparticle/MoS2 Nanosheet Composites with Superior Performances for Lithium Ion Batteries

A novel composite consisting of graphene‐like MoS₂ nanosheets and ultrasmall Fe₃O₄ nanoparticles (≈3.5 nm) is synthesized as an anode for lithium ion battery application. In such composite anode, MoS₂ nanosheets provide flexible substrates for the nanoparticle decoration, accommodating the volume changes of Fe₃O₄ during cycling process; while Fe₃O₄ nanoparticles primarily act as spacers to stabilize the composite structure, making the active surfaces of MoS₂ nanosheets accessible for electrolyte penetration during charge/discharge processes. Owing to the high reversible capacity provided by the MoS₂ nanosheets and the superior high rate performance offered by ultrasmall Fe₃O₄ nanoparticles, superior cyclic and rate performances are achieved by Fe₃O₄/MoS₂ anode during the subsequent electrochemical tests, delivering 1033 and 224 mAh g^?1 at current densities of 2000 and 10 000 mA g^?1, respectively.     

AlGaAs/GaAs tunnel junctions in a 4-J tandem solar cell

TheⅢ-Ⅴcompound tandem solar cell is a third-generation new style solar cell with ultra-high efficiency. The energy band gaps of the sub-cells in a GaInP/GaAs/InGaAs/Ge 4-J tandem solar cell are 1.8,1.4,1.0 and 0.7 eV,respectively.In order to match the currents between sub-cells,tunnel junctions are used to connect the sub-cells.The characteristics of the tunnel junction,the material used in the tunnel junction,the compensation of the tunnel junction to the overall cell’s characteristics,the tunnel junction’s influence on the current density of sub-cells and the efficiency increase are discussed in the paper.An AlGaAs/GaAs tunnel junction is selected to simulate the cell’s overall characteristics by PC1D,current densities of 16.02,17.12,17.75 and 17.45 mA/cm² are observed,with a V_oc of 3.246 V,the energy conversion efficiency under AM0 is 33.9%.     

One‐Step Hydrothermal Synthesis of 2D Hexagonal Nanoplates of α‐Fe2O3/Graphene Composites with Enhanced Photocatalytic Activity

There has been significant progress in the field of semiconductor photocatalysis, but it is still a challenge to fabricate low‐cost and high‐activity photocatalysts because of safety issues and non‐secondary pollution to the environment. Here, 2D hexagonal nanoplates of α‐Fe₂O₃/graphene composites with relatively good distribution are synthesized for the first time using a simple, one‐step, template‐free, hydrothermal method that achieves the effective reduction of the graphene oxide (GO) to graphene and intimate and large contact interfaces of the α‐Fe₂O₃ nanoplates with graphene. The α‐Fe₂O₃/graphene composites showed significantly enhancement in the photocatalytic activity compared with the pure α‐Fe₂O₃ nanoplates. At an optimal ratio of 5 wt% graphene, 98% of Rhodamine (RhB) is decomposed with 20 min of irradiation, and the rate constant of the composites is almost four times higher than that of pure α‐Fe₂O₃ nanoplates. The decisive factors in improving the photocatalytic performance are the intimate and large contact interfaces between 2D hexagonal α‐Fe₂O₃ nanoplates and graphene, in addition to the high electron withdrawing/storing ability and the highconductivity of reduced graphene oxide (RGO) formed during the hydrothermal reaction. The effective charge transfer from α‐Fe₂O₃ nanoplates to graphene sheets is demonstrated by the significant weakening of photoluminescence in α‐Fe₂O₃/graphene composites.     

Efficient Self‐Assembly Synthesis of Uniform CdS Spherical Nanoparticles‐Au Nanoparticles Hybrids with Enhanced Photoactivity

The treatment of environmental pollution has become one of the most critical issues in the world. Despite the progress made in the study of semiconductor photocatalysis, it is still a challenge to obtain photocatalysts with high activity through relatively simple fabrication processes. In this work, monodisperse CdS spherical nanoparticles (SNPs) of various sizes and good crystallinity are obtained by only adjusting the starting ratio of reactants and the reaction temperature, exhibiting high photocatalytic performances. The photocatalytic rate constant of the ≈ 100 nm CdS SNPs, especially, is more than double that of P25. Furthermore, 3‐mercaptopropyltrimethoxysilane is used to assist the interaction between ≈ 200 nm CdS SNPs and citrate‐stabilized Au nanoparticles (NPs). The significant increase of photocatalytic activity is confirmed by the degradation of Rodamine B (RhB) under Xe light irradiation. At the optimal Au concentration (0.5 wt%), the prepared nanohybrids show the highest photocatalytic activity, exceeding that of pure CdS two times. The superior photocatalytic performances of the CdS SNPs‐Au nanohybrids can be attributed to the intimate interfacial contact between CdS SNPs and Au NPs, which is a contributing factor to the improvement of transfer and the fate of photogenerated charge carriers from CdS SNPs to Au NPs.     

铅基卤素钙钛矿阻变式存储器研究进展

随着数字通信在大数据以及物联网等领域的应用,推动了下一代存储设备的发展.阻变式存储器因其功耗低、尺寸可调、操作速度快等优点被认为是最有前景的信息存储器件之一.近年来,兼具成本低、带隙可调、载流子扩散长度长、离子迁移速率快、载流子迁移率高等优点的铅基卤素钙钛矿,在阻变式存储器领域引起了广泛关注.主要对铅基卤素钙钛矿阻变式...     

Enhanced Photocatalytic Activity of Lead-Free Cs2TeBr6/g-C3N4 Heterojunction Photocatalyst and Its Mechanism

In this study, a new type of lead-free double perovskite Cs₂TeBr₆ combined with metal-free semiconductor g-C₃N₄ heterojunction is constructed and used for photocatalytic CO₂ reduction for the first time. The S-scheme charge transfer mechanism between Cs₂TeBr₆ and g-C₃N₄ is systematically verified by X-ray photoelectron spectroscopy (XPS), electron spin resonance (ESR) and in situ Fourier infrared spectroscopy(FT-IR). The formation of S-type heterojunction makes the photocatalyst have higher charge separation ability and highest redox ability. The results show that 5%-CTB/CN heterojunction material has the best photocatalytic reduction effect on CO₂ under visible light irradiation. After 3 h of illumination, the yield of CO and CH₄ are 468.9 µmol g⁻¹ and 61.31 µmol g⁻¹, respectively. The yield of CO is 1.5 times and 32 times that of pure Cs₂TeBr₆ and g-C₃N₄, and the yield of CH₄ is doubled compared with pure Cs₂TeBr₆. However, g-C₃N₄ almost does not produce CH₄, which indicates that the construction of heterojunction helps to further improve the photocatalytic performance of the material. This study provides a new idea for the preparation of Cs₂TeBr₆/g-C₃N₄ heterojunction and its effective interfacial charge separation.     

基建期矿山提前采矿的技术研究

大型矿山一般基建期较长,资金投入大。为了缓解资金压力,都希望基建期在保证基建进度的前提下提前采矿,以增强自身的发展能力。介绍了某大型铁矿在基建期实现提前采矿的方案和措施。     

基于CAN的磁浮列车车载诊断网络系统的设计

以上海磁浮运营示范线的德国高速磁悬浮列车为背景,以磁悬浮列车的国产化为目的;简要介绍了基于CAN的磁浮列车车载诊断网络系统;为了确保高速磁浮列车可靠的运行,设计了基于CAN的车载诊断网络系统,它是对车载设备诊断信息进行采集、分析并诊断,形成各车载设备的详细诊断信息,而这些诊断信息可以提供给列车驾驶员和地面控制中心进行参考,实时了解磁浮列车的状态;介绍了CAN总线技术及其特点,以及车载诊断网络系统的基本结构和诊断功能。     

湖南柿竹园柴山井下复杂低品位多金属原矿白钨矿选矿工艺研究

湖南柿竹园复杂低品位多金属矿中白钨矿回收,根据其工艺矿物学特性,先采用常温浮选工艺流程获得白钨粗精矿,再将粗精矿进行加温精选,加盐酸酸浸,最终获得了白钨精矿品位69.17%、回收率76.39%的良好试验指标。