二硫族二维半导体材料的制备及性能研究

发布时间：2018-01-09 00:27

  本文关键词：二硫族二维半导体材料的制备及性能研究　出处：《电子科技大学》2017年博士论文　论文类型：学位论文

  更多相关文章： 二硫族化合物 锂离子电池 电化学性能 析氢反应

【摘要】：二硫族化合物(MX_2,M为钼、钨、铼等过渡族金属,X为硫、硒等)是继石墨烯之后发现的最重要二维半导体材料。因其独特的二维层状晶体结构,二硫族二维半导体材料具有优异的电学、光学、力学、电化学、催化等特性,在微电子、光电子、传感器、电化学储能、电催化制氢等领域展现出巨大的应用潜力,迅速成为当前的国际研究前沿与热点。本论文以二硫化铼(Re S_2)、二硒化铼(Re Se_2)、二硫化钨(WS_2)二维层状纳米材料为研究对象,首先,系统研究Re S_2及其复合物的可控制备,进一步研究Re S_2的微观结构及还原氧化石墨烯(r GO)、碳纳米管(CNTs)对Re S_2电化学与电催化性能的影响规律及机制;然后,研究Re Se_2的制备和电化学性能,并对比研究Re S_2与Re Se_2电催化析氢规律及机制;最后,研究三维石墨烯泡沫(3DGF)对WS_2电催化析氢性能的影响规律及机制。主要研究内容与结果如下:1. 提出了一种采用物理气相沉积制备大面积、连续Re S_2薄膜的新方法。研究表明,以Re S_2粉末为原料,在氩气气氛中加热到900°C时,Re S_2粉末受热蒸发形成的Re S_2分子在目标衬底上沉积形成Re S_2薄膜。通过控制生长条件,制备的Re S_2薄膜厚度约2.30 nm(三个Re S_2分子层),在厘米尺度连续、厚度均一,该薄膜是由~250 nm的晶粒构成的多晶薄膜。2.提出了一种一步水热法制备Re S_2纳米材料的方法,并研究了其电化学与电催化性能。研究表明,一步水热法制备的Re S_2粉末呈现出独特的菊花状三维、多孔微球结构,微球尺寸为1~2μm,由少数层Re S_2纳米片自组装构成。在0.2 C充放电情况下,Re S_2微球的首次放电比容量为843.0 m Ah g~(-1),循环30次后,仍能保持422.1 m Ah g~(-1)的放电比容量,远优于商用Re S_2粉末的电化学性能,这主要是由于合成的Re S_2微球的结构可以提供更多的反应活性位、增大电极活性材料与电解液的接触面积。此外,该Re S_2微球的电催化析氢起始电位为-100 m V vs RHE,塔菲尔斜率为153.5 m V dec~(-1)。3.研究了Re S_2与r GO的原位复合生长及其电化学与电催化性能。研究表明,当未引入r GO时,Re S_2会自组装成三维多孔微球结构;当引入r GO时,Re S_2不再形成微球结构,而是与r GO自组装成r GO/Re S_2/r GO分层复合结构。当该分层复合结构的Re S_2/r GO作为锂离子电池负极时,在0.2 C时可逆比容量高达885 m Ah g~(-1),循环50次后的可逆比容量仍能保持745 m Ah g~(-1),远高于纯Re S_2,该分层复合结构的Re S_2/r GO还具有良好的倍率充放电特性。与纯Re S_2相比,Re S_2/r GO也展现出更优异的电催化析氢特性:其析氢起始电位为-100 m V vs RHE,塔菲尔斜率为107.4 m V dec~(-1),循环稳定性高。4.研究了Re S_2与CNTs的原位复合生长及其电化学与电催化性能。研究发现,当引入CNTs的时候,Re S_2不再形成微球结构,而是与CNTs一起组装形成Re S_2/CNTs复合管状结构。与Re S_2相比,当Re S_2/CNTs复合物作为锂离子电池负极材料时展现更优异的电化学性能:其0.5 C的放电比容量高达847 m Ah g~(-1),循环100次后放电比容量是793 m Ah g~(-1),保持了93.6%的放电比容量,该复合材料还具有良好的倍率充放电特性。与纯Re S_2相比,Re S_2/CNTs也展现出更优异的电催化析氢特性:其析氢起始电位为-80 m V vs RHE,塔菲尔斜率为93.5 m V dec~(-1),循环稳定性高。5.采用一步水热反应法制备了Re Se_2纳米材料并研究了其电催化析氢性能与电化学性能。研究表明,一步水热法制备的Re Se_2是由少数层Re Se_2纳米片自组装的菊花状三维多孔微球结构,微球的直径约1μm。相较于Re S_2微球,该Re Se_2微球具有更加优异的电催化析氢性能:具有小的析氢起始电位(-80 m V vs RHE),更低的塔菲尔斜率(67.5 m V dec~(-1)),循环稳定性与催化析氢持续性高。此外,Re Se_2在400 m A g~(-1)时的可逆比容量为340.4 m Ah g~(-1),循环100次后的可逆比容量只有62.6 m Ah g~(-1),倍率充放电性能一般,Re Se_2的电化学性能具有巨大的优化空间。6.采用热分解方法在三维泡沫镍(3DNi)和3DGF表面直接生长WS_2,并研究其电催化析氢性能。研究表明,与三维二硫化钨/泡沫镍(WS_2/Ni)相比,三维二硫化钨/石墨烯/泡沫镍(WS_2/graphene/Ni)表现出更优异的电催化析氢性能:具有更低的析氢起始电位(-40 m V vs RHE),更小的塔菲尔斜率(79 m V dec~(-1)),更大的阴极电流密度(阴极电流密度大小为10 m A cm~(-2)时,析氢电势为-87 m V vs RHE;析氢过电势为250 m V vs RHE时,阴极电流密度大小为119.1 m A cm~(-2)),且WS_2/graphen/Ni具有更优异的循环稳定性。WS_2/graphen/Ni具有更优异电催化性能的主要原因在于,高导电的三维网络状石墨烯不仅可作为WS_2生长的模板,增加基底与WS_2之间的结合强度,可以增大催化剂的负载质量,而且还能有效防止电解液对镍的腐蚀作用。
[Abstract]:Two compounds (MX_2, M for molybdenum, tungsten, rhenium and other transition metal X as sulfur, selenium, etc.) is the most important semiconductor materials found after two-dimensional graphene after. Due to its unique two-dimensional layered crystal structure, two dimensional Chalcogenide Semiconductor material with excellent electrical, optical, mechanical, electrochemical and catalytic characteristics, in microelectronics, optoelectronics, sensors, electrochemical energy storage, such as electrochemical hydrogen production field show great potential applications, become an international research frontier and hotspot. In this paper, two rhenium sulfide (Re S_2), two (Re Se_2) selenide rhenium tungsten sulfide (WS_2), two a two-dimensional layered nano material as the research object, firstly, controllable preparation system of Re S_2 and its composite, microstructure of the further study of Re S_2 and reduction of graphene oxide (R GO), carbon nanotubes (CNTs) effect and mechanism of Re S_2 electrochemical and electrocatalytic performance; then, research Re Se_2 preparation and electrochemical properties, and a comparative study of Re S_2 and Re Se_2 electrocatalytic hydrogen evolution law and mechanism; finally, the research of three-dimensional graphene foam (3DGF) effects and mechanism of WS_2 hydrogen. The main research contents and results are as follows: 1. a large area of mining preparation by physical vapor deposition, a new method for continuous Re S_2 films. The results show that the Re S_2 powder as the raw material is heated to 900 DEG C in argon atmosphere, the Re S_2 Re S_2 powder heated molecules formed by the evaporation of formation of Re films on S_2 substrates. The target by controlling the growth conditions of Re S_2 films the thickness of the prepared about 2.30 nm (three Re, S_2 molecular layer) in the CM scale continuous, uniform thickness, the thin film is polycrystalline thin film composed of.2. crystal ~250 nm proposed a method of preparing Re nano S_2 one-step hydrothermal method, and its electrochemical and electrocatalytic Chemical properties. The results show that one step hydrothermal preparation of Re S_2 powders exhibit unique three-dimensional shape of chrysanthemum, porous microspheres, microspheres size is 1~2 m, by a layer of Re S_2 nano self-assembled film. In 0.2 C discharge, Re S_2 microspheres of the initial discharge capacity was 843 m Ah g~ (-1), after 30 cycles, can still maintain 422.1 m (-1) Ah g~ the discharge capacity of the electrochemical performance is far better than the commercial Re S_2 powder, which is mainly due to the structure of Re S_2 microspheres can provide more reaction active sites, enlarge the contact area of electrode material and electrolyte. In addition, the electric potential of the hydrogen evolution reaction of the initial Re S_2 -100 m V vs microspheres for RHE, Tafel slope of 153.5 m (-1) V dec~.3. Re S_2 and R GO on the growth of in situ composite and its electrochemical and electrocatalytic properties. The results show that when no introduction of R GO, Re S_2 self assembly The three-dimensional structure of porous microspheres; when the introduction of R GO, Re S_2 is no longer the formation of microspheres structure, but with the R GO R GO/Re S_2/r GO self-assembled into layered composite structure. When the layered structure of Re S_2/r GO as the cathode of lithium ion battery, at 0.2 C reversible capacity up to 885 m Ah g~ (-1 after 50 cycles, the reversible) can keep 745 m Ah g~ (-1), the specific capacity is still far higher than that of pure Re S_2, the layered structure of Re S_2/r GO also has a good rate charge and discharge characteristics. Compared with pure Re S_2, Re S_2/r GO also showed the electrocatalytic hydrogen evolution more excellent characteristics the hydrogen evolution potential of -100 m V vs start RHE, Tafel slope of 107.4 m (-1), V dec~.4. Re on the cycle stability of high S_2 and CNTs composite in situ growth and its electrochemical and electrocatalytic properties. The study found that, when the introduction of CNTs, Re S_2 is no longer the formation of microspheres structure, but assembled together with CNTs The formation of Re S_2/CNTs composite tubular structure. Compared with the Re S_2 show superior electrochemical performance when Re S_2/CNTs composites as anode materials for lithium ion batteries, the discharge specific capacity of 0.5 C up to 847 m Ah g~ (-1), after 100 cycles the discharge capacity is 793 m Ah g~ (-1). Keep 93.6% of the discharge capacity, the composite material has the characteristics of good rate charge discharge. Compared with pure Re S_2, Re S_2/CNTs also showed excellent electrocatalytic hydrogen evolution characteristics: the hydrogen evolution potential of -80 m V vs start RHE, Tafel slope of 93.5 m (-1), V dec~ cycle high stability.5. by one-step hydrothermal method to prepare the Re Se_2 nano materials and study its electrocatalytic properties and electrochemical properties. The results show that one step hydrothermal preparation of Re Se_2 structure by a layer of Re nano Se_2 chrysanthemum three-dimensional porous microspheres self-assembly, the diameter of microspheres 绾，

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