CuSe纳米片、纳米棒簇的水热合成研究

使用Cu2+-EDTA配合物和不同浓度的Na2SeSO3溶液,利用水热法制得了粒径均匀(边长约为700 nm,厚度约为200 nm)的六方相CuSe纳米片和纳米棒簇.在XRD,SEM,TEM表征结果的基础上,对CuSe纳米片和纳米棒簇形成机理进行了研究.通过对比,我们发现Cu2+-EDTA的使用对纳米片的形成有重要作用.为了研究产品的光学性质,使用了紫外可见光谱(UV-vis)和荧光光谱(PL)对样品进行了性能表征.结果表明其Eg=2.5e V,在λ=249 nm的激光激发下,在306 nm出现了明显的荧光发射峰.

溶剂热法合成In_2S_3/CuSe核壳结构粉体

本文以氯化铜、氯化铟、硫脲、亚硒酸以及硒粉为原料,乙二醇及乙二胺为溶剂,采用常压溶剂热法制备了硫化铟为核硒化铜为壳（In2S3/CuSe）的核壳结构复合粉体。主要探讨了反应温度、不同反应原料以及不同表面活性剂对产物物相以及形貌的影响。通过采用X射线衍射（XRD）、扫描电镜（SEM）对产物的物相、形貌以及组成进行了表征。实验结果表明：常压溶剂热条件下可以制备得In2S3/CuSe复合粉体,其最佳反应工艺参数是：于160℃下合成In2S3粉体为核,于100℃下合成包裹在In2S3表面的CuSe粉体从而获得In2S3/CuSe核壳结构复合粉。在该工艺参数下合成产物的形貌主要由圆球状颗粒组成,粉体的粒径分布在1~2μm。此外,本文也通过添加不同种类表面活性剂对产物的形貌进行了控制。

溶剂热法制备CuSe纳米线薄膜

以铜片和硒粉为原料,苯为溶剂,通过调控反应物的配比、反应物浓度、反应温度和反应时间等因素,采用溶剂热法直接在铜基底上制备出六方晶系的硒化铜纳米线薄膜.分别利用X-射线转靶衍射仪(XRD),场发射扫描电子显微镜(FESEM),透射电子显微镜(TEM)表征了产物的晶体结构与形貌,探索了CuSe纳米线薄膜的形成过程,并使用荧光分光光度法(PL)对最终产物的性质进行了表征.实验结果表明:这种CuSe纳米线的直径为100～200 nm,长度为5μm,其荧光发光峰为301 nm.

以CuSe纳米粒子为催化剂制备超长ZnSe纳米线

采用化学气相沉积的方法,以Zn粉末为原料,CuSe纳米粒子为催化剂,在Si衬底上成功制备了毫米级ZnSe纳米线。用X射线衍射、EDS和SEM对产物的结构、成分和形貌进行了测试与表征。结果表明:生长的ZnSe纳米线为立方闪锌矿结构,长度达0.35～0.7mm,Zn和Se的摩尔比为1?0.97,其室温光致发光谱显示在325nm波长激发下,ZnSe纳米线在439nm处呈现自由激子的强烈发射,表明生长的ZnSe纳米线具有高的结晶质量。纳米线生长符合氧化还原反应下的气液固生长机制,并证明Cu3Zn合金充当了实际的ZnSe纳米线生长催化剂。

溶剂热法合成In_2Se_3/CuSe复合粉及CuInSe_2薄膜的制备

采用常压下两步溶剂热法合成了In2Se3/CuSe复合粉,并以其为原料,通过喷涂成膜后快速热处理制备了CuInSe2(CIS)薄膜。利用XRD、FE-SEM、EDS对In2Se3/CuSe复合粉的晶体结构和形貌进行分析表征,研究了溶剂热合成过程中的反应温度、表面活性剂对In2Se3/CuSe复合粉体物相及形貌的影响。结果表明:以InCl3·4H2O、Se粉为原料,聚乙二醇-400、水合肼、醋酸为溶剂于120℃下反应30 min可以成功合成出结晶性良好的纯相In2Se3纳米球,直径分布在50～100 nm之间;以In2Se3纳米粉作为中间产物,分散于乙二醇溶剂中,加入Se源溶液(水合肼溶解Se粉)及CuCl2·2H2O,90℃下反应30 min可获得In2Se3/CuSe复合粉,其中CuSe呈不规则团聚状均匀分布在In2Se3纳米球的周围,且当加入0.2 g CTAB时获得的In2Se3/CuSe复合粉分散性较好。采用FE-SEM、EDS、XRF和Raman光谱对预置膜和快速热处理后获得的CIS薄膜的形貌和成分进行表征。结果表明:将In2Se3/CuSe复合粉制备成"墨水"后涂覆在镀Mo玻璃基板上,快速升温至550℃可成功获得致密的CIS薄膜。

In2Se3／CuSe核壳结构微纳粉的合成及其喷涂热处理制备CuInSe2薄膜

分别采用超声微波溶剂热法、常压溶剂热法及高压溶剂热法制备In_2Se_3/CuSe粉体,研究不同方法制备In_2Se_3/CuSe粉体的物相、形貌,并利用涂覆–快速热处理法制作薄膜太阳电池吸收层。通过XRD、Raman、FESEM和TEM对样品的物相、形貌和组成进行了表征。结果表明:超声微波溶剂热法和常压溶剂热法得到的产物是以In_2Se_3+CuSe混合相的形式存在,高压溶剂热法合成的In_2Se_3/CuSe粉体则呈核壳结构,(以In_2Se_3为核,CuSe为壳)。涂覆–快速热处理法制备CIS薄膜的FESEM照片结果表明,高压溶剂热法合成的In_2Se_3/CuSe更容易获得平整致密的薄膜。将该CIS薄膜直接用于电池器件的组装,获得的光电性能参数:Voc为50 m V,Jsc为8 m A/cm^2。

CuSe表面修饰的第一性原理研究

单层CuSe属于体相为非层状的二维材料,本质上具有金属性质,因此不适合在电子器件中应用.本文通过外部原子修饰的方法实现CuSe电子结构的改变,采用密度泛函理论的第一性原理研究了单层CuSe在顶位、中心和桥位添加第二周期原子后的能带结构,重点分析了单层CuSe添加Li和B原子的电子结构,包括能带结构、态密度、差分电荷密度和晶体轨道哈密顿布居分析.添加Li原子后,从能带结构的结果来看,三个位置都能实现CuSe由金属性转为半导体性,且Li原子更倾向修饰在CuSe的六角形中心,带隙约为1.77 eV;在Cu原子的顶部位置添加B原子也可以实现CuSe具有半导体性,带隙约为1.2 eV.通过差分电荷密度和晶体轨道哈密顿布居的结果来看,B原子用B-Se极性共价键结合在单层CuSe的顶部.第一原理揭示了从单层CuSe到Cu XSe(X=Li,B)的金属到半导体转变的实现,计算结果使CuSe在未来的电子设备中使用成为可能.

Theoretical analysis and experimental verification of thermal decomposition mechanism of CuSe

Experiments on the thermal decomposition of CuSe were carried out by using a thermogravimetric analyzer(TGA)at different heating rates.The kinetic parameters and mechanisms were discussed based on model-free and model-based analyses.The decomposition rate and decomposition behavior of CuSe were investigated by using a vacuum thermogravimetric furnace.The results showed that the R3 model was identified as the most probable mechanism function under the present experimental conditions.The average values of activation energy and the pre-exponential factor were 12.344 J/mol and 0.152 s^(−1),respectively.The actual decomposition rate of CuSe was found to be 0.0030 g/(cm^(2)·min).

(CuSe)_n(n=1-10)团簇结构稳定性与磁性的理论研究

本文采用包含广义梯度近似的密度泛函理论对铜、硒二元团簇(CuSe)_n(n=1-10)的结构稳定性与磁性质进行系统的研究,发现:(CuSe)_n(n=1-10)二元团簇的原子总数为8时几何结构出现由平面向立体的转变行为,且Cu3Se3为"幻数"构型.同时,(CuSe)_n(n=1-10)团簇的平均结合能比同尺寸单质铜团簇的大,因此混合团簇(CuSe)_n(n=1-10)具有比单质铜团簇更强的稳定性;另外,根据(CuSe)_n(n=1-10)团簇的二阶差分能和HOMO-LUMO能隙随尺寸增加的演化趋势可获知,Cu8Se8的结构极其稳定.最后,对团簇磁性的研究发现,铜硒团簇展现出比较特别的磁性,其中,Cu3Se3的总磁矩为3μB,且磁性主要来源于硒原子,而当n=4,6,8和10时,(CuSe)_n(n=1-10)团簇磁性出现淬灭现象.

Ab initio investigation of the structural and unusual electronic properties of α-CuSe (klockmannite)

In this article, a computational analysis has been performed on the structural properties and predominantly on the electronic properties of the α-CuSe （klockmannite） using density functional theory. The studies in this work show that the best structural results, in comparison to the experimental values, belong to the PBEsol-GGA and WC-GGA functionals. However, the best results for the bulk modulus and density of states （DOSs） are related to the local density approximation （LDA） functional. Through utilized approaches, the LDA is chosen to investigate the electronic structure. The results of the electronic properties and geometric optimization of α-CuSe respectively show that this compound is conductive and non-magnetic. The curvatures of the energy bands crossing the Fermi level explicitly reveal that major charge carriers in CuSe are holes, whose density is estimated to be 0.86×1022 hole/cm3. In particular, the Fermi surfaces in the first Brillouin zone demonstrate interplane conductivity between （001） planes. Moreover, the charge carriers among them are electrons and holes simultaneously. The conductivity in CuSe is mainly due to the hybridization between the d orbitals of Cu atoms and the p orbitals of Se atoms. The former orbitals have the dual nature of localization and itinerancy.

Band engineering of honeycomb monolayer CuSe via atomic modification

Two-dimensional monolayer copper selenide(CuSe)has been epitaxially grown and predicted to host the Dirac nodal line fermion(DNLF).However,the metallic state of monolayer CuSe inhibits the potential application of nanoelectronic devices in which a band gap is needed to realize on/off properties.Here,we engineer the band structure of monolayer CuSe which is an analogue of a p-doped system via external atomic modification in an effort to realize the semiconducting state.We find that the H and Li modified monolayer CuSe shifts the energy band and opens an energy gap around the Fermi level.Interestingly,both the atomic and electronic structures of monolayer CuHSe and CuLiSe are very different.The H atoms bind on top of Se atoms of monolayer CuSe with Se-H polar covalent bonds,annihilating the DNLF band of monolayer CuSe dominated by Se orbitals.In contrast,Li atoms prefer to adsorb at the hexagonal center of CuSe,preserving the DNLF band of monolayer CuSe dominated by Se orbitals,but opening band gaps due to a slight buckling of the CuSe layer.The realization of metal-to-semiconductor transition from monolayer CuSe to CuXSe(X=H,Li)as revealed by first-principles calculations makes it possible to use CuSe in future electronic devices.

Molecular Beam Epitaxy Growth and Scanning Tunneling Microscopy Study of Pyrite CuSe2 Films on SrTiO3

We perform molecular beam epitaxy growth and scanning tunneling microscopy study of copper diselenide （CuSe2 ） films on SrTiO3 （001）. Using a Se-rich condition, the single-phase pyrite CuSe2 grows in the Stranski-Krastanov （layer-plus-island） mode with a preferential orientation of （111）. Our careful inspection of both the as-grown and post-annealed CuSe2 films at various temperatures invariably shows a Cu-terminated surface, which, depending on the annealing temperature, reconstructs into two distinct structures 2 ×√3 and √x ×√3-R30°. The Cu termi- nation is supported by the depressed density of states near the Fermi level, measured by in-situ low temperature scanning tunneling spectroscopy. Our study helps understand the preparation and surface chemistry of transition metal pyrite dichalcogenides thin films.

In-situ imaging electrocatalysis in a solid-state Li-O_(2) battery with CuSe nanosheets as air cathode

The development of highly efficient catalysts in the cathodes of rechargeable Li-O_(2) batteries is a considerable challenge.To enhance the electrochemical performance of the Li-O_(2) battery,it is essential to choose a suitable catalyst material.Copper selenide(CuSe)is considered as a more promising cathode catalyst material for Li-O_(2) battery due to its better conductivity and rich electrochemical active sites.However,its electrochemical reaction and fundamental catalytic mechanism remain unclear till now.Herein,in-situ environmental transmission electron microscopy technique was used to study the catalysis mechanism of the CuSe nanosheets in Li-O_(2) batteries during discharge and charge processes.It is found that Li_(2)O was formed and decomposed around the ultrafine-grained Cu during the discharge and charge processes,respectively,demonstrating excellent cycling.This indicate that the freshly formed ultrafine-grained Cu in the conversion reaction catalyzed the latter four-electron-transfer oxygen reduction reaction,leading to the formation of Li_(2)O.Our study provides important understanding of the electrochemistry of the LiO_(2) nanobatteries,which will aid the development of high-performance Li-O_(2) batteries for energy storage applications.

溶剂热制备CuSe纳米片及其储钠性能研究

由于资源储量丰富,钠离子电池已经成为下一代储能电池的有力候选方案之一.过渡金属硒化物由于具有易于制备、导电性能较好等优点而引起广泛关注.本文使用溶剂热方法成功地制备出六方相CuSe纳米片,并将其作为钠离子电池负极材料,结合多种测试及表征手段对其储钠性能与电化学反应机理进行了研究.电化学测试表明CuSe具有优异的电化学性能.在5 A g^(-1)电流密度下的可逆容量为183.5 mAh g^(-1),容量保持率为70.7%(相对0.1 A g^(-1)电流密度下的可逆容量而言).在2 A g^(-1)循环800圈后,容量保持率高达97.4%.非原位X射线粉末衍射和选区电子衍射测试结果表明,CuSe在储钠过程中会发生不可逆的转化反应生成Cu_(2-x)Se,后续的循环实际上是Cu_(2-x)Se进行钠离子的转化反应.

Large-scale preparation of fernwort-like single-crystalline superstructures of CuSe as Fenton-like catalysts for dye decolorization

A simple green hydrothermal template-free method was developed to prepare single-crystalline superstructures of fern- wort-like copper selenide （CuSe） in large-scale by using polyvinylpyrrolidone （PVP） as both reductant and surfactant for the first time. Time-dependent morphologic evolution was made in order to explore the formation mechanism of the as-prepared product. The copper selenides with different morphologies, phases and structural forms could be prepared by varying the synthesis parameters, such as precursor molar ratios, precursor combinations, and the molecular weight of PVP. The fernwort-like superstructures of CuSe show excellent Fenton-like catalytic activities in degrading malachite green （MG） and rhodamine B （RhB）. These catalysts play an important role in the degradation process of MG and RhB solution with the aid of H202 which can yield highly reactive hydroxyl radicals （HO.）. Besides, the as-prepared CuSe catalyst is stable and reusable, thus it could be applied to the treatment of the dye contaminated waste water.

In situ observation of the electrochemical behavior of Li–CO_(2)/O_(2)batteries in an environmental transmission electron microscope

Li–CO_(2)/O_(2)batteries,a promising energy storage technology,not only provide ultrahigh discharge capacity but also capture CO_(2)and turn it into renewable energy.Their electrochemical reaction pathways'ambiguity,however,creates a hurdle for their practical application.This study used copper selenide(CuSe)nanosheets as the air cathode medium in an environmental transmission electron microscope to in situ study Li–CO_(2)/O_(2)(mix CO_(2)as well as O_(2)at a volume ratio of 1:1)and Li–O_(2)batteries as well as Li–CO_(2)batteries.Primary discharge reactions take place successively in the Li–CO_(2)/O_(2)–CuSe nanobattery:(I)4Li^(+)+O_(2)+4e^(−)→2Li_(2)O;(II)Li_(2)O+CO_(2)→Li_(2)CO_(3).The charge reaction proceeded via(III)2Li_(2)CO_(3)→4Li^(+)+2CO_(2)+O_(2)+4e^(−).However,Li–O_(2)and Li–CO_(2)nanobatteries showed poor cycling stability,suggesting the difficulty in the direct decomposition of the discharge product.The fluctuations of the Li–CO_(2)/O_(2)battery's electrochemistry were also shown to depend heavily on O_(2).The CuSe‐based Li–CO_(2)/O_(2)battery showed exceptional electrochemical performance.The Li^–CO_(2)/O_(2)battery offered a discharge capacity apex of 15,492 mAh g^(−1) and stable cycling 60 times at 100 mA g^(−1).Our research offers crucial insight into the electrochemical behavior of Li–CO_(2)/O_(2),Li–O_(2),and Li–CO_(2)nanobatteries,which may help the creation of high‐performance Li–CO_(2)/O_(2)batteries for energy storage applications.

高等教育多元化收费价格模型的构建

通过分析影响高等教育价格的主要因素及高等教育本身的多元性,基于"谁受益,谁付费"的市场经济原则,并兼顾教育效率与社会公平,构建了一种以高等教育成本为基础、高等教育本身的多元性为依据、生源地经济状况为参照的多元化收费价格CUSEE模型,并利用该模型计算了我国2003年度高校的收费价格,其结果与当年的实际情况基本相吻合。CUSEE模型克服了高校以往收费价格的单一、静态等不足,体现了高等教育本身的多样性,兼顾了效率和社会公平,其既可在宏观也可在微观上为高等教育的收费价格提供一种理论模型。

小型微/纳米级三坐标测量机的研制

介绍一套低成本小型三维坐标测量机的研制过程,作为微/纳米级超精密测量设备,整体机台结构采用花岗岩材料;X/Y轴的移动平台利用压电材料摩擦驱动与挠性变形原理,长短两行程可达25 mm范围及5 nm的微位移,藉自行研发的衍射干涉激光尺,位置回馈测量系统可具有0.025 nm的分辨率;测量探头在一般DVD光读取头的自动聚焦原理基础上改装,最佳分辨率可达2.5 nm.该雏形机适于测量微机电组件、微型器件及膜厚等.

超声SMI技术检测颈动脉粥样硬化斑块新生血管的应用价值

目的:探讨采用超声SMI技术评价颈动脉粥样硬化斑块新生血管的临床价值。方法:选择2017年3月-2018年2月本院收治的680例动脉粥样硬化患者,共计736个斑块。所有患者均行颈动脉常规超声扫描、CEUS与SMI检查,观察CEUS、SMI评分与颈动脉斑块厚度的相关性,并分析SMI检查对非脑梗死死、新发脑梗死与陈旧脑梗死的评估作用。结果:伴随SMI评分与CEUS评分上升,患者的斑块厚度明显加重,不同SMI评分与CEUS评分患者的斑块厚度比较,差异均有统计学意义(P<0.05),并且SMI评分与CEUS评分存在中等一致性(Kappa=0.436)。脑梗组的SMI评分高于非脑梗组,新发脑梗组的SMI评分高于陈旧脑梗组,差异均有统计学意义(P<0.05)。结论:超声SMI技术可以更加清晰地显示管腔,可准确地评价斑块情况,显示粥样硬化斑块内的微细血流,与CEUS技术的诊断效果相当,并可避免造影剂的辅助。斑块内新生血管与脑梗,尤其是新发脑梗相关。超声SMI技术可以为临床提供更多无创方便的诊断方法,从而为临床规划治疗方案提供依据。

基于大数据的小微企业统计信息采集策略

小微企业由于信息严重不对称导致融资难、融资贵、贷款难等问题,基于大数据来源之一的互联网社交媒体的小微企业信息采集是获取小微企业信息数据的重要途径。文章面对爆发式增长的互联网信息资源,利用主题聚焦网络爬虫技术、数据库技术、Java技术等设计并实现由基于链接结构分析的链接地址URL筛选及采集、基于模板节点匹配的网页正文信息抽取、数据入库三个功能模块组成的小微企业统计信息自动采集系统,采集到的数据以结构化数据的形式存储到My SQL数据库中,为后续数据挖掘与分析提供良好的数据支持。结果表明,文章所提出的信息自动采集系统采集效率较高,能够适应小微企业统计信息采集的需求。