發(fā)布時(shí)間：2018-01-24 22:24

  本文關(guān)鍵詞： 直接甲酸燃料電池 高性能 Pd 電催化劑 催化行為　出處：《西南大學(xué)》2014年博士論文　論文類型：學(xué)位論文

【摘要】：直接甲酸燃料電池(Direct Formic Acid Fuel Cell, DFAFC),具有能量轉(zhuǎn)換效率高、安全可靠等特點(diǎn),和氫氧燃料電池相比,具有明顯的體積比能量?jī)?yōu)勢(shì),同時(shí)以液體甲酸為燃料,便于使用傳統(tǒng)的汽油運(yùn)輸、儲(chǔ)存和銷售設(shè)備。因此在作為汽車動(dòng)力以及便攜式電源領(lǐng)域具有廣闊的應(yīng)用前景。然而DFAFC昂貴的價(jià)格極大地限制了其商業(yè)化發(fā)展,其中重要原因之一是該電池需要使用大量貴金屬鉑(Pt)催化劑,導(dǎo)致電池成本過高。因此,研究和制備具有高性能、低價(jià)位的陽(yáng)極甲酸氧化和陰極氧還原(Oxygen reduction reaction, ORR)催化劑用于DFAFC,對(duì)加快其發(fā)展和應(yīng)用具有重要的意義,但目前在研發(fā)中仍然存在很大的挑戰(zhàn)。鈀(Pd),具有和Pt相似的晶體結(jié)構(gòu)和電子性能,價(jià)格相對(duì)便宜并且具有更高的抗一氧化碳(CO)中毒能力,從而成為一種有希望取代Pt的催化劑。近年來,納米科學(xué)技術(shù)的進(jìn)步和不斷深入發(fā)展了在納米尺度范圍內(nèi)設(shè)計(jì)和制備高性能催化劑的有效方法。本論文工作從納米尺度設(shè)計(jì)和調(diào)控材料合成,發(fā)展了制備催化劑的新方法和研究催化劑碳載體以提高催化性能,制備出了一系列高性能Pd陰極和陽(yáng)極電催化劑,進(jìn)而對(duì)其納米尺度的電催化行為進(jìn)行了研究和討論,發(fā)掘了電極過程動(dòng)力學(xué)的科學(xué)內(nèi)涵。 第一章綜述簡(jiǎn)要概述了燃料電池的原理、分類、特點(diǎn)和用途等。重點(diǎn)介紹了DFAFC催化劑及其反應(yīng)機(jī)理,分析了當(dāng)前催化劑常用的幾種碳載體材料,同時(shí)也提出了DFAFC催化劑在科學(xué)和實(shí)踐中的挑戰(zhàn)。最后介紹了本論文的研究目的、主要內(nèi)容以及創(chuàng)新點(diǎn)。 第二章實(shí)驗(yàn)設(shè)計(jì)及表征方法本章介紹了實(shí)驗(yàn)過程中所使用的主要儀器和試劑,同時(shí)也分別描述了DFAFC催化劑的研究所使用的主要物理化學(xué)表征方法和電化學(xué)催化行為表征方法。 第三章DNA調(diào)控的Pd納米晶/碳納米管催化劑及其氧還原催化行為的研究CNTs具有較大的比表面積以及良好的導(dǎo)電性和化學(xué)穩(wěn)定性能,有作為優(yōu)良催化劑載體的潛力。但是CNTs本身表面缺少活性基團(tuán),不利于金屬顆粒的沉積。常用的方法是使用強(qiáng)酸回流來氧化CNTs,但會(huì)嚴(yán)重腐蝕CNTs并降低其導(dǎo)電性能。本論文研究通過DNA的芳香族堿基對(duì)和CNTs的石墨化表面的非共價(jià)ππ-ππ鍵相互作用對(duì)CNTs進(jìn)行修飾,不僅保持了其原有的優(yōu)良結(jié)構(gòu)和導(dǎo)電性能,而且DNA規(guī)則排列的磷酸基團(tuán)可以調(diào)控生長(zhǎng)超小的,在CNTs表面均勻沉積的Pd納米晶(平均粒徑約是3.4nm),制備出了高性能Pd/DNA-CNTs催化劑。比較未經(jīng)DNA調(diào)控制備的Pd/CNTs以及商業(yè)化Pd/C催化劑,Pd/DNA-CNTs展示出更好的ORR電催化活性和穩(wěn)定性。這種使用DNA調(diào)控制備高性能催化劑的方法,應(yīng)可以擴(kuò)大應(yīng)用到其它能源轉(zhuǎn)換／存儲(chǔ)系統(tǒng)中。 第四章DNA修飾石墨烯并調(diào)控高活性Pd納米晶作為甲酸氧化催化劑及其催化行為的研究Pt是DFAFC陽(yáng)極常用的甲酸氧化催化劑,但是Pt的催化活性不夠優(yōu)良并且抗CO中毒能力較差。因此本論文研究選用DNA在具有高比表面積和優(yōu)良導(dǎo)電性能的Graphene表面調(diào)控制備了高活性的Pd納米晶作為甲酸氧化催化劑,即Pd-DNA@Graphene。通過TEM分析發(fā)現(xiàn),平均粒徑約5nm的Pd納米晶均勻分散在Graphene表面。催化劑對(duì)甲酸氧化的電催化行為通過CV、LSV以及i-t等進(jìn)行了研究。通過實(shí)驗(yàn)數(shù)據(jù)分析發(fā)現(xiàn),Pd-DNA@Graphene催化劑展示出比Pd-Graphene和商業(yè)化Pd/C催化劑更高的峰電流密度和標(biāo)準(zhǔn)交換電流密度(i0)、更低的電荷轉(zhuǎn)移電阻(Rct),說明我們制備的Pd-DNA@Graphene催化劑具有更好的甲酸氧化催化性能。另外,Pd-DNA@Graphene催化劑比Pd-Graphene和商業(yè)化Pd/C催化劑有更高的長(zhǎng)時(shí)間運(yùn)行穩(wěn)定性。因此,我們制備的Pd-DNA@Graphene催化劑在DFAFC中具有較高的應(yīng)用價(jià)值。 第五章一步法制備超小Pd納米晶/石墨烯催化劑及其甲酸氧化催化行為的研究由于傳統(tǒng)制備Pd納米催化劑的方法較為復(fù)雜、步驟冗繁,顆粒容易團(tuán)聚并且難以實(shí)現(xiàn)均勻分散,嚴(yán)重影響了其ECSA,從而造成催化活性的降低。本論文研究使用甲酸作為還原劑在水熱的條件下一步還原制備了平均粒徑約4.3nm的超小的Pd納米晶均勻分散在Graphene表面,制備出了高性能Pd@Graphene催化劑。和商業(yè)化Pd/C催化劑相比,Pd@Graphene催化劑對(duì)于甲酸氧化反應(yīng)具有更高的峰電流密度和i0、更低的Rct以及更好的穩(wěn)定性能。本論文也研究了Pd@Graphene催化劑的高效催化機(jī)制。這種一步法制備高效催化劑的方法,簡(jiǎn)單方便,容易實(shí)現(xiàn),具有廣泛的應(yīng)用潛力。 第六章不同納米結(jié)構(gòu)的碳材料作為載體制備的Pd催化劑及其對(duì)甲酸氧化催化行為影響的研究為了考察不同納米結(jié)構(gòu)的碳材料作為載體對(duì)制備的Pd催化劑甲酸氧化催化行為的影響,并選擇出更高效的Pd催化劑,本論文研究分別選用零維的XC-72,一維的CNTs,二維的G以及三維的3D-RGO作為載體,制備了Pd@XC-72,Pd@CNTs,Pd@G以及Pd@3D-RGO催化劑并對(duì)其甲酸氧化催化行為進(jìn)行了研究。和Pd@XC-72、Pd@CNTs以及Pd@G相比,Pd@3D-RGO不僅具有最大的比表面積和ECSA,而且還有最高的峰電流密度和i0、最低的Rct、最好的穩(wěn)定性能。因此,Pd@3D-RGO是一種性能優(yōu)良的甲酸氧化催化劑。另外,本論文研究不僅發(fā)現(xiàn)了三維的3D-RGO是一種比較理想的催化劑碳載體材料,而且也拓展了設(shè)計(jì)、合成和選擇催化劑及其碳載體材料的應(yīng)用基礎(chǔ)理論。 第七章結(jié)論和工作展望本章對(duì)論文研究得到的結(jié)論進(jìn)行了總結(jié)并展望了這一領(lǐng)域以后要繼續(xù)開展的研究工作。
[Abstract]:Direct formic acid fuel cell (Direct Formic Acid Fuel Cell, DFAFC), has high energy conversion efficiency, safe and reliable, compared with the fuel cell, has obvious advantages in energy and volume ratio, liquid acid as fuel, easy to use the traditional gasoline transportation, storage and sale of equipment. It has broad application prospects as in the automobile power and portable power. However, the DFAFC price greatly limit its commercial development, one of the most important reasons is the battery need to use a large number of precious metal platinum (Pt) catalyst, resulting in high battery cost. Therefore, the study and preparation of high performance anode and cathode oxygen, the oxidation of formic acid low price reduction (Oxygen reduction reaction, ORR) catalysts for DFAFC, has an important significance to accelerate its development and application, but the research still exists great challenges War. (Pd), PD and Pt has the similar crystal structure and electronic properties, the price is relatively cheap and has higher resistance to carbon monoxide (CO) poisoning ability, thus becoming a promising substitute for Pt catalyst. In recent years, nano science and technology progress and the development of effective design method in nanometer scale the range and preparation of high performance catalysts. This work from nano scale design and control materials, the development of a new method of preparing catalyst and catalyst carrier of carbon to improve the catalytic performance, preparation of a series of high performance Pd cathode and anode catalyst, and the electrocatalytic behavior of nano scale are studied and discussed, to explore the scientific connotation of electrode kinetics.
In the first chapter a brief overview of the principle of fuel cell, classification, characteristics and uses. Focusing on the DFAFC catalyst and its reaction mechanism, analyzes the current several commonly used carbon catalyst carrier materials, but also challenges the DFAFC catalyst in science and practice. Finally it introduces the research purpose, main content as well as innovation.
The second chapter is about experimental design and characterization. In this chapter, the main instruments and reagents used in the experiment are introduced. At the same time, the main physical and chemical characterization methods and Electrochemical Catalytic Behavior Characterization Methods of DFAFC catalysts are also described.
Study of CNTs Pd nanocrystals / third chapter DNA regulation of carbon nanotube catalyst and its catalytic behavior of oxygen reduction has a larger surface area and good conductivity and chemical stability, as the excellent catalyst carrier potential. But CNTs itself lack of surface active groups, is not conducive to the deposition of metal particles. The commonly used method is to use acid reflux to the oxidation of CNTs, but CNTs will be severe corrosion and reduce its electrical properties. This paper bases on the aromatic through DNA and CNTs graphite surface non covalent pi pi pi pi bond interaction of CNTs was modified, not only maintains the excellent original structure and electrical conductivity, and the phosphate group DNA regular arrangement can control the growth of ultra small, Pd in nanocrystalline CNTs uniformly deposited on the surface of the (average particle size is about 3.4nm), were prepared by the high performance Pd/DNA-CNTs catalyst without DNA control. The prepared Pd/CNTs and commercialized Pd/C catalysts show better ORR electrocatalytic activity and stability than Pd/DNA-CNTs. This method using DNA to control high performance catalysts should be extended to other energy conversion / storage systems.
The fourth chapter DNA modified graphene and the control of high activity of Pd nanocrystals as the formic acid oxidation catalyst and its catalytic behavior of Pt catalysts for DFAFC oxidation of formic acid is commonly used in the anode, but the catalytic activity of Pt is excellent and CO anti poisoning ability is poor. So this paper selects DNA in Graphene with high surface area and excellent conductive surface adjustment the controlled synthesis of Pd nanocrystals with high activity as formic acid oxidation catalyst, Pd-DNA@Graphene. is found through the analysis of TEM, Pd nanocrystals with an average particle size of about 5nm were uniformly dispersed on the surface of Graphene. The electrocatalytic behavior of catalyst for formic acid oxidation by CV, LSV and I-T were studied. Through the analysis of experimental data showed that the Pd-DNA@Graphene catalyst show the peak current density and higher standards than Pd-Graphene and commercial Pd/C catalyst exchange current density (I0), lower electric charge transfer Resistance (Rct), we illustrate the oxidation of formic acid catalytic performance of Pd-DNA@Graphene catalysts prepared has better. In addition, Pd-DNA@Graphene catalyst has long time running stability is higher than Pd-Graphene and commercial Pd/C catalyst. Therefore, the application value of our Pd-DNA@Graphene catalyzed by the agent is higher in DFAFC.
The fifth chapter is the research of one step preparation of ultra small Pd nanoparticles / graphene catalyst and its catalytic oxidation of formic acid behavior because the traditional methods of preparing Pd nano catalyst is more complex, cumbersome steps, easy to agglomerate particles and is difficult to achieve uniform dispersion, which seriously affected the ECSA, resulting in the decrease of catalytic activity. This paper use formic acid as reducing agent under hydrothermal conditions of one-step reduction preparation the average particle size of about 4.3nm ultra small Pd nanoparticles uniformly dispersed on the surface of Graphene was prepared by high performance Pd@Graphene catalyst. Compared with commercial Pd/C catalyst, Pd@Graphene catalyst has a peak current density and higher I0 for the oxidation of formic acid the reaction, lower Rct and better stability. This paper also studies the efficient catalytic mechanism of Pd@Graphene catalyst. This method of one step preparation of catalysts with high efficiency, simple and convenient, It is easy to realize and has wide application potential.
The sixth chapter on Pd catalysts for carbon materials with different nanostructures as carrier preparation and its effect on the catalytic oxidation of formic acid in order to investigate the behavior of carbon materials with different nanostructures as the effect of the support on the catalytic behavior of Pd catalyst for the oxidation of formic acid was prepared, and the choice of the Pd catalyst is more efficient, this paper selected zero dimension XC-72, one CNTs, two dimensional G and three-dimensional 3D-RGO as carrier, Pd@XC-72, prepared by Pd@CNTs, Pd@G and Pd@3D-RGO catalysts and studied its catalytic behavior. The oxidation of formic acid and Pd@XC-72, compared to Pd@CNTs and Pd@G, Pd@3D-RGO not only has the largest surface area and ECSA, but also the highest peak current the density and I0, the lowest Rct, stable performance best. Therefore, Pd@3D-RGO is an excellent catalyst for the oxidation of formic acid. In addition, this thesis not only found three dimension is 3D-RGO An ideal catalyst for carbon carrier, and it has also expanded the basic theory of the design, synthesis and selection of catalysts and their carbon carrier materials.
In the seventh chapter, the conclusion and work prospect are summarized and the future research work in this field is prospected.

【學(xué)位授予單位】：西南大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2014
【分類號(hào)】：O643.36;TM911.4

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 沈培康;加快燃料電池產(chǎn)業(yè)化進(jìn)程的建議[J];電池;2002年03期

相關(guān)博士學(xué)位論文 前1條

1 程年才;直接甲酸燃料電池用Pd/C催化劑制備及其性能研究[D];武漢理工大學(xué);2010年

，

本文編號(hào)：1461186