二氧化鉬及其復(fù)合材料的制備與電催化制氫性能的研究
發(fā)布時(shí)間：2018-09-12 11:11
【摘要】：20世紀(jì)以來人類社會(huì)進(jìn)入高速發(fā)展的階段,人口增長,科技創(chuàng)新,使人們的生活發(fā)生了翻天覆地的變化。而為了支撐起現(xiàn)代人的日常生活,我們對能源的需求也不斷增大。化石燃料大量無節(jié)制的開采與使用雖然滿足了一時(shí)的發(fā)展需求,但是長遠(yuǎn)來講,其產(chǎn)生的污染則是無法忽視的問題。因此,研究探索新型的清潔能源材料對人類社會(huì)的可持續(xù)發(fā)展具有重要的意義。氫氣是一個(gè)良好的能量載體,燃燒后只會(huì)產(chǎn)生水,對環(huán)境沒有危害,因此世界各國都將氫氣作為未來的重要能源進(jìn)行研究。然而作為一種二次能源,想要得到氫氣必須要經(jīng)過能量轉(zhuǎn)換的步驟。目前由于引入了化石燃料的使用,工業(yè)化的氫氣制取方式在生產(chǎn)氫氣的過程中會(huì)生成大量溫室氣體,因此,尋找新型無污染的制氫方法迫在眉睫。電解水制氫技術(shù)是一種高效且無污染的制氫方式,通過電解槽直接將電能轉(zhuǎn)化為化學(xué)能儲(chǔ)存。目前在生產(chǎn)中使用的電極主要是鉑碳類材料,其過電勢小,并且可以達(dá)到較大的電流密度。但是由于貴金屬鉑的含量稀少且價(jià)格昂貴限制了其大范圍的應(yīng)用,在這種情況下,尋找新型的電催化制氫材料具有很大的意義。二氧化鉬作為一種具有金屬性的半導(dǎo)體擁有良好的電導(dǎo)率,同時(shí)由于其特殊的結(jié)構(gòu)也被廣泛地用于有機(jī)催化領(lǐng)域。本論文主要是針對二氧化鉬這一金屬相半導(dǎo)體及其復(fù)合物的制備以及它們在電催化制氫領(lǐng)域的應(yīng)用進(jìn)行了深入的研究。首先,我們利用三氧化鉬與鉬粉間的氧化還原反應(yīng)制備了附載在石墨烯上的二氧化鉬納米顆粒并測試其電催化制氫性能；之后,我們利用鉬片代替鉬粉在鉬片上直接生長了一層二氧化鉬薄膜,使鉬片作為集流體來進(jìn)一步提升二氧化鉬的電催化制氫性能；在實(shí)驗(yàn)中我們發(fā)現(xiàn)二氧化鉬與鉑之間存在“貴金屬——載體間強(qiáng)相互作用”,因此我們制備了均勻負(fù)載鉑的二氧化鉬／碳納米管復(fù)合材料,并發(fā)現(xiàn)其展現(xiàn)了優(yōu)異的電催化制氫性能,可以與商用鉑碳電極媲美。通過以上一系列的研究,我們認(rèn)為二氧化鉬由于其特殊的性質(zhì),在電催化領(lǐng)域具有很大的應(yīng)用前景。本論文的內(nèi)容分為以下四章：第一章為緒論,文中首先概述電解水制氫技術(shù)與氫電極反應(yīng)的概念和基本原理,然后簡要介紹了氫析出反應(yīng)催化劑的選擇與其設(shè)計(jì)和制備原則,接著介紹了近年來這一領(lǐng)域的發(fā)展,以及常見的硫化物、磷化物與復(fù)合材料催化劑。最后討論了本論文的研究內(nèi)容及意義。在第二章中,我們介紹了一種利用簡單的氧化還原反應(yīng)機(jī)理制備二氧化鉬／還原石墨烯復(fù)合物的方法,利用石墨烯的空間限制作用我們成功控制了二氧化鉬顆粒的尺寸。由于石墨烯與二氧化鉬間的協(xié)同效應(yīng),在二氧化鉬和石墨烯本身都沒有優(yōu)異的電催化制氫活性的前提下,制備的二氧化鉬/還原石墨烯復(fù)合物展示了優(yōu)良的催化活性,190 mV的起始過電勢,塔菲爾斜率達(dá)到49 mV/dec。除此之外,該材料在酸性和堿性條件下都顯示了良好的循環(huán)穩(wěn)定性。經(jīng)過分析我們認(rèn)為,這種非同尋常的性能提升可以歸功于復(fù)合材料更小的粒徑,更多的活性位點(diǎn)與更好的導(dǎo)電性。第三章中,我們報(bào)道了不含貴金屬的高效電催化制氫電極：直接生長在鉬片上的磷摻雜二氧化鉬納米顆粒。鉬片作為集流體,得到的電極展示了良好的電催化制氫活性：小的起始過電勢80 mV,達(dá)到10 mA cm-2的陰極電流時(shí)過電勢為135 mV,塔菲爾斜率為62 mV/dec,優(yōu)于其他的二氧化鉬基的催化材料。另外,經(jīng)過2000次CV測試之后,我們發(fā)現(xiàn)這種磷摻雜二氧化鉬薄膜/鉬片電極具有很好的酸性穩(wěn)定性。這種新穎的直接在鉬片上生長磷摻雜二氧化鉬的方法得到了一種高效的HER催化劑,拓展了我們合成不含貴金屬、高效、低廉并且環(huán)境友好的HER催化劑的視野。第四章中,在本章工作中,我們綜合了鉑、二氧化鉬以及碳納米管的特性,制備出一種超低鉑含量的復(fù)合材料作為高效的電催化產(chǎn)氫催化劑,同時(shí)在酸性介質(zhì)中體現(xiàn)了良好的穩(wěn)定性。這種鉑-二氧化鉬-碳納米管的復(fù)合材料由簡單的氧化還原反應(yīng)制備得到,同時(shí)顯示出卓越的電催化活性和良好的穩(wěn)定性,它展現(xiàn)出了幾乎為0的起始過電勢,43 mV/dec的塔菲爾斜率,以及在過電勢為60 mV和84mV時(shí)達(dá)到10 mA cm-2和20 mA cm-2的法拉第電流密度。由于二氧化鉬與鉑之間的強(qiáng)作用力以及較高的電導(dǎo)率,這種鉑-二氧化鉬-碳納米管的復(fù)合材料的電催化產(chǎn)氫效率和穩(wěn)定性要優(yōu)于商用的鉑碳電催化劑。引人注目的是,如此高的催化活性和增強(qiáng)的穩(wěn)定性僅僅是由含有0.5 wt%鉑的復(fù)合催化劑得到的。我們的工作在研發(fā)高效率、低鉑含量的電催化劑領(lǐng)域開啟了一條新的道路,同時(shí)保證了理想的催化活性和耐用性。
[Abstract]:Since the 20th century, human society has entered a stage of rapid development, population growth, scientific and technological innovation, so that people's lives have undergone earth-shaking changes. In order to support the daily life of modern people, our demand for energy is increasing. Although a large number of uncontrolled exploitation and use of fossil fuels meet the development needs of the moment, but In the long run, the pollution caused by hydrogen is a problem that can not be ignored. Therefore, it is of great significance to study and explore new clean energy materials for the sustainable development of human society. However, as a secondary energy source, hydrogen must go through the steps of energy conversion. At present, due to the introduction of fossil fuels, industrialized hydrogen production will generate a large number of greenhouse gases in the process of hydrogen production, so it is urgent to find a new pollution-free hydrogen production method. Hydrogen production technology is an efficient and non-polluting way of hydrogen production. Electric energy is directly converted into chemical energy by electrolytic cells. The electrodes used in production are mainly platinum-carbon materials with low overpotential and high current density. As a kind of metal semiconductor, molybdenum dioxide has good conductivity and is widely used in the field of organic catalysis because of its special structure. This paper mainly focuses on molybdenum dioxide, a metal phase semiconductor and its application. The preparation of the composite and its application in the field of electrocatalytic hydrogen production have been studied in depth. Firstly, molybdenum dioxide nanoparticles supported on graphene have been prepared by the oxidation-reduction reaction between molybdenum trioxide and molybdenum powder, and their electrocatalytic hydrogen production performance has been tested. A layer of molybdenum dioxide film was grown to further enhance the electrocatalytic hydrogen production performance of molybdenum dioxide by using molybdenum sheet as a collector. In the experiment, we found that there was a "strong interaction between noble metal and support" between molybdenum dioxide and platinum, so we prepared a uniformly loaded platinum molybdenum dioxide / carbon nanotube composite. Through the above series of studies, we believe that molybdenum dioxide has a great application prospect in the field of electrocatalysis because of its special properties. The contents of this paper are divided into the following four chapters: Chapter 1 is an introduction, and the electrolytic water is first summarized in this paper. The concept and basic principle of hydrogen production technology and hydrogen electrode reaction are introduced. Then the selection of hydrogen precipitation catalyst, its design and preparation principle are briefly introduced. Then the recent development in this field, as well as the common sulfides, phosphides and composite catalysts are introduced. Finally, the research contents and significance of this paper are discussed. In Chapter 2, we introduce a method of preparing molybdenum dioxide/reduced graphene composites by a simple oxidation-reduction reaction mechanism. We have successfully controlled the size of molybdenum dioxide particles by using the space-limiting effect of graphene. Due to the synergistic effect between graphene and molybdenum dioxide, there is no molybdenum dioxide or graphene itself. On the premise of excellent electrocatalytic activity for hydrogen production, the prepared molybdenum dioxide/reduced graphene composite exhibited excellent catalytic activity. The initial overpotential of 190 mV and the slope of Tafel reached 49 mV/dec. In addition, the material exhibited good cyclic stability in both acidic and alkaline conditions. The unusual performance improvement can be attributed to the smaller particle size, more active sites and better conductivity of the composite. In Chapter 3, we report a highly efficient electrocatalytic hydrogen production electrode without precious metals: phosphorus-doped molybdenum dioxide nanoparticles grown directly on molybdenum sheets. Molybdenum sheets as a collector exhibit good performance. Electrocatalytic hydrogen production activity: low initial overpotential of 80 mV, cathode current of 10 mA cm-2, overpotential of 135 mV, Tafel slope of 62 mV / dec, better than other catalytic materials based on molybdenum dioxide. In addition, after 2000 CV tests, we found that this phosphorus-doped molybdenum dioxide film / molybdenum sheet electrode has good acidity stability. Qualitative. This novel method of directly growing phosphorus-doped molybdenum dioxide on molybdenum sheets yields an efficient HER catalyst, which broadens our vision for the synthesis of HER catalysts without precious metals, high efficiency, low cost and environmental friendliness. A composite material with ultra-low platinum content was prepared as a highly efficient electrocatalytic hydrogen production catalyst and exhibited good stability in acidic media. The composite material was prepared by simple oxidation-reduction reaction and showed excellent electrocatalytic activity and stability. The initial overpotential of almost zero, the Tafel slope of 43 mV/dec, and the Faraday current density of 10 mA cm-2 and 20 mA cm-2 at overpotential of 60 mV and 84 mV have been found. It is noticeable that such high catalytic activity and enhanced stability are obtained only from a composite catalyst containing 0.5 wt% platinum. Our work opens a new path in the development of high-efficiency, low-platinum electrocatalysts and ensures an ideal catalysis. Activity and durability.
【學(xué)位授予單位】：中國科學(xué)技術(shù)大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類號(hào)】：TQ136.12;O643.36
本文編號(hào)：2238825
[Abstract]:Since the 20th century, human society has entered a stage of rapid development, population growth, scientific and technological innovation, so that people's lives have undergone earth-shaking changes. In order to support the daily life of modern people, our demand for energy is increasing. Although a large number of uncontrolled exploitation and use of fossil fuels meet the development needs of the moment, but In the long run, the pollution caused by hydrogen is a problem that can not be ignored. Therefore, it is of great significance to study and explore new clean energy materials for the sustainable development of human society. However, as a secondary energy source, hydrogen must go through the steps of energy conversion. At present, due to the introduction of fossil fuels, industrialized hydrogen production will generate a large number of greenhouse gases in the process of hydrogen production, so it is urgent to find a new pollution-free hydrogen production method. Hydrogen production technology is an efficient and non-polluting way of hydrogen production. Electric energy is directly converted into chemical energy by electrolytic cells. The electrodes used in production are mainly platinum-carbon materials with low overpotential and high current density. As a kind of metal semiconductor, molybdenum dioxide has good conductivity and is widely used in the field of organic catalysis because of its special structure. This paper mainly focuses on molybdenum dioxide, a metal phase semiconductor and its application. The preparation of the composite and its application in the field of electrocatalytic hydrogen production have been studied in depth. Firstly, molybdenum dioxide nanoparticles supported on graphene have been prepared by the oxidation-reduction reaction between molybdenum trioxide and molybdenum powder, and their electrocatalytic hydrogen production performance has been tested. A layer of molybdenum dioxide film was grown to further enhance the electrocatalytic hydrogen production performance of molybdenum dioxide by using molybdenum sheet as a collector. In the experiment, we found that there was a "strong interaction between noble metal and support" between molybdenum dioxide and platinum, so we prepared a uniformly loaded platinum molybdenum dioxide / carbon nanotube composite. Through the above series of studies, we believe that molybdenum dioxide has a great application prospect in the field of electrocatalysis because of its special properties. The contents of this paper are divided into the following four chapters: Chapter 1 is an introduction, and the electrolytic water is first summarized in this paper. The concept and basic principle of hydrogen production technology and hydrogen electrode reaction are introduced. Then the selection of hydrogen precipitation catalyst, its design and preparation principle are briefly introduced. Then the recent development in this field, as well as the common sulfides, phosphides and composite catalysts are introduced. Finally, the research contents and significance of this paper are discussed. In Chapter 2, we introduce a method of preparing molybdenum dioxide/reduced graphene composites by a simple oxidation-reduction reaction mechanism. We have successfully controlled the size of molybdenum dioxide particles by using the space-limiting effect of graphene. Due to the synergistic effect between graphene and molybdenum dioxide, there is no molybdenum dioxide or graphene itself. On the premise of excellent electrocatalytic activity for hydrogen production, the prepared molybdenum dioxide/reduced graphene composite exhibited excellent catalytic activity. The initial overpotential of 190 mV and the slope of Tafel reached 49 mV/dec. In addition, the material exhibited good cyclic stability in both acidic and alkaline conditions. The unusual performance improvement can be attributed to the smaller particle size, more active sites and better conductivity of the composite. In Chapter 3, we report a highly efficient electrocatalytic hydrogen production electrode without precious metals: phosphorus-doped molybdenum dioxide nanoparticles grown directly on molybdenum sheets. Molybdenum sheets as a collector exhibit good performance. Electrocatalytic hydrogen production activity: low initial overpotential of 80 mV, cathode current of 10 mA cm-2, overpotential of 135 mV, Tafel slope of 62 mV / dec, better than other catalytic materials based on molybdenum dioxide. In addition, after 2000 CV tests, we found that this phosphorus-doped molybdenum dioxide film / molybdenum sheet electrode has good acidity stability. Qualitative. This novel method of directly growing phosphorus-doped molybdenum dioxide on molybdenum sheets yields an efficient HER catalyst, which broadens our vision for the synthesis of HER catalysts without precious metals, high efficiency, low cost and environmental friendliness. A composite material with ultra-low platinum content was prepared as a highly efficient electrocatalytic hydrogen production catalyst and exhibited good stability in acidic media. The composite material was prepared by simple oxidation-reduction reaction and showed excellent electrocatalytic activity and stability. The initial overpotential of almost zero, the Tafel slope of 43 mV/dec, and the Faraday current density of 10 mA cm-2 and 20 mA cm-2 at overpotential of 60 mV and 84 mV have been found. It is noticeable that such high catalytic activity and enhanced stability are obtained only from a composite catalyst containing 0.5 wt% platinum. Our work opens a new path in the development of high-efficiency, low-platinum electrocatalysts and ensures an ideal catalysis. Activity and durability.
【學(xué)位授予單位】：中國科學(xué)技術(shù)大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類號(hào)】：TQ136.12;O643.36
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