本文關鍵詞：二硫族二維半導體材料的制備及性能研究　出處：《電子科技大學》2017年博士論文　論文類型：學位論文

  更多相關文章： 二硫族化合物 鋰離子電池 電化學性能 析氫反應

【摘要】：二硫族化合物(MX_2,M為鉬、鎢、錸等過渡族金屬,X為硫、硒等)是繼石墨烯之后發(fā)現(xiàn)的最重要二維半導體材料。因其獨特的二維層狀晶體結(jié)構(gòu),二硫族二維半導體材料具有優(yōu)異的電學、光學、力學、電化學、催化等特性,在微電子、光電子、傳感器、電化學儲能、電催化制氫等領域展現(xiàn)出巨大的應用潛力,迅速成為當前的國際研究前沿與熱點。本論文以二硫化錸(Re S_2)、二硒化錸(Re Se_2)、二硫化鎢(WS_2)二維層狀納米材料為研究對象,首先,系統(tǒng)研究Re S_2及其復合物的可控制備,進一步研究Re S_2的微觀結(jié)構(gòu)及還原氧化石墨烯(r GO)、碳納米管(CNTs)對Re S_2電化學與電催化性能的影響規(guī)律及機制;然后,研究Re Se_2的制備和電化學性能,并對比研究Re S_2與Re Se_2電催化析氫規(guī)律及機制;最后,研究三維石墨烯泡沫(3DGF)對WS_2電催化析氫性能的影響規(guī)律及機制。主要研究內(nèi)容與結(jié)果如下:1. 提出了一種采用物理氣相沉積制備大面積、連續(xù)Re S_2薄膜的新方法。研究表明,以Re S_2粉末為原料,在氬氣氣氛中加熱到900°C時,Re S_2粉末受熱蒸發(fā)形成的Re S_2分子在目標襯底上沉積形成Re S_2薄膜。通過控制生長條件,制備的Re S_2薄膜厚度約2.30 nm(三個Re S_2分子層),在厘米尺度連續(xù)、厚度均一,該薄膜是由~250 nm的晶粒構(gòu)成的多晶薄膜。2.提出了一種一步水熱法制備Re S_2納米材料的方法,并研究了其電化學與電催化性能。研究表明,一步水熱法制備的Re S_2粉末呈現(xiàn)出獨特的菊花狀三維、多孔微球結(jié)構(gòu),微球尺寸為1~2μm,由少數(shù)層Re S_2納米片自組裝構(gòu)成。在0.2 C充放電情況下,Re S_2微球的首次放電比容量為843.0 m Ah g~(-1),循環(huán)30次后,仍能保持422.1 m Ah g~(-1)的放電比容量,遠優(yōu)于商用Re S_2粉末的電化學性能,這主要是由于合成的Re S_2微球的結(jié)構(gòu)可以提供更多的反應活性位、增大電極活性材料與電解液的接觸面積。此外,該Re S_2微球的電催化析氫起始電位為-100 m V vs RHE,塔菲爾斜率為153.5 m V dec~(-1)。3.研究了Re S_2與r GO的原位復合生長及其電化學與電催化性能。研究表明,當未引入r GO時,Re S_2會自組裝成三維多孔微球結(jié)構(gòu);當引入r GO時,Re S_2不再形成微球結(jié)構(gòu),而是與r GO自組裝成r GO/Re S_2/r GO分層復合結(jié)構(gòu)。當該分層復合結(jié)構(gòu)的Re S_2/r GO作為鋰離子電池負極時,在0.2 C時可逆比容量高達885 m Ah g~(-1),循環(huán)50次后的可逆比容量仍能保持745 m Ah g~(-1),遠高于純Re S_2,該分層復合結(jié)構(gòu)的Re S_2/r GO還具有良好的倍率充放電特性。與純Re S_2相比,Re S_2/r GO也展現(xiàn)出更優(yōu)異的電催化析氫特性:其析氫起始電位為-100 m V vs RHE,塔菲爾斜率為107.4 m V dec~(-1),循環(huán)穩(wěn)定性高。4.研究了Re S_2與CNTs的原位復合生長及其電化學與電催化性能。研究發(fā)現(xiàn),當引入CNTs的時候,Re S_2不再形成微球結(jié)構(gòu),而是與CNTs一起組裝形成Re S_2/CNTs復合管狀結(jié)構(gòu)。與Re S_2相比,當Re S_2/CNTs復合物作為鋰離子電池負極材料時展現(xiàn)更優(yōu)異的電化學性能:其0.5 C的放電比容量高達847 m Ah g~(-1),循環(huán)100次后放電比容量是793 m Ah g~(-1),保持了93.6%的放電比容量,該復合材料還具有良好的倍率充放電特性。與純Re S_2相比,Re S_2/CNTs也展現(xiàn)出更優(yōu)異的電催化析氫特性:其析氫起始電位為-80 m V vs RHE,塔菲爾斜率為93.5 m V dec~(-1),循環(huán)穩(wěn)定性高。5.采用一步水熱反應法制備了Re Se_2納米材料并研究了其電催化析氫性能與電化學性能。研究表明,一步水熱法制備的Re Se_2是由少數(shù)層Re Se_2納米片自組裝的菊花狀三維多孔微球結(jié)構(gòu),微球的直徑約1μm。相較于Re S_2微球,該Re Se_2微球具有更加優(yōu)異的電催化析氫性能:具有小的析氫起始電位(-80 m V vs RHE),更低的塔菲爾斜率(67.5 m V dec~(-1)),循環(huán)穩(wěn)定性與催化析氫持續(xù)性高。此外,Re Se_2在400 m A g~(-1)時的可逆比容量為340.4 m Ah g~(-1),循環(huán)100次后的可逆比容量只有62.6 m Ah g~(-1),倍率充放電性能一般,Re Se_2的電化學性能具有巨大的優(yōu)化空間。6.采用熱分解方法在三維泡沫鎳(3DNi)和3DGF表面直接生長WS_2,并研究其電催化析氫性能。研究表明,與三維二硫化鎢/泡沫鎳(WS_2/Ni)相比,三維二硫化鎢/石墨烯/泡沫鎳(WS_2/graphene/Ni)表現(xiàn)出更優(yōu)異的電催化析氫性能:具有更低的析氫起始電位(-40 m V vs RHE),更小的塔菲爾斜率(79 m V dec~(-1)),更大的陰極電流密度(陰極電流密度大小為10 m A cm~(-2)時,析氫電勢為-87 m V vs RHE;析氫過電勢為250 m V vs RHE時,陰極電流密度大小為119.1 m A cm~(-2)),且WS_2/graphen/Ni具有更優(yōu)異的循環(huán)穩(wěn)定性。WS_2/graphen/Ni具有更優(yōu)異電催化性能的主要原因在于,高導電的三維網(wǎng)絡狀石墨烯不僅可作為WS_2生長的模板,增加基底與WS_2之間的結(jié)合強度,可以增大催化劑的負載質(zhì)量,而且還能有效防止電解液對鎳的腐蝕作用。
[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 綰，

本文編號：1399314