發(fā)布時間：2018-05-18 04:43

  本文選題：燃料電池 + 直接甲酸燃料電池�。� 參考：《西南大學》2017年碩士論文

【摘要】：直接甲酸燃料電池(Direct formic acid fuel cells,DFAFCs)具有能量轉換效率高,安全無毒而且環(huán)境友好等優(yōu)點,在汽車動力以及便攜式電源等方面具有廣泛的應用前景。然而,DFAFCs常用的陽極Pd/C催化劑活性和穩(wěn)定性不夠優(yōu)良,成為限制其商業(yè)化發(fā)展的重要因素。納米科技的進步和深入,發(fā)展了在相關尺度范圍內(nèi)設計和制備高性能催化劑的有效方法。均勻分散的小粒徑Pd納米顆粒在提高材料利用率的同時展現(xiàn)出更高的電化學活性比表面積,而特殊納米結構Pd催化劑粗糙的表面和多孔的結構通常存在大量的缺陷——提供豐富的扭結原子作為催化活性位點,從而有利于甲酸氧化過程中電極過程動力學的提升。然而,合成高性能特殊納米結構的Pd催化劑仍然在基礎研究和技術方面面臨著很大挑戰(zhàn)。本論文從調(diào)控催化劑形貌、尺寸等方面入手,設計并制備了具有高性能的均勻超細Pd納米催化劑以提升催化性能。借助透射電子顯微鏡(TEM)、掃描電子顯微鏡(SEM)、X射線衍射儀(XRD)、X射線能譜儀(EDS)等對所制備的催化劑的結構、形貌進行表征,通過循環(huán)伏安法(CV)和計時-電流法(i-t)等測試技術對其電化學行為和性能進行了詳細的對比和分析。實驗結果表明,聚二烯丙基二甲基氯化銨(PDDA)協(xié)助CO還原法制備均勻超小Pd納米晶/石墨烯催化劑,由于其多孔結構載體石墨烯與表面潔凈、超小且均勻分散的Pd納米晶協(xié)同催化作用,對甲酸氧化展現(xiàn)出比商業(yè)化Pd/C催化劑更優(yōu)良催化性能。而多枝化Pd納米枝晶因其高度枝化且粗糙的表面,提供了豐富的扭結和臺階原子作為活性位點,以及它具有獨特的多孔結構和高的可接觸表面積促進了電化學動力學過程,在展現(xiàn)出比Pd/C催化劑更優(yōu)異甲酸氧化行為催化性能的同時,為甲酸氧化催化過程提出了一些科學性見解。本論文內(nèi)容共分以下五章:第一章綜述簡要概括了燃料電池的發(fā)展歷程、原理、分類、性能和優(yōu)勢等,對DFAFCs的工作原理以及相應催化劑分別進行了介紹,同時也概述了一些常見催化劑的制備方法。最后對本論文的研究意義和主要內(nèi)容進行了論述。第二章實驗設計、材料表征及電化學測試技術本章歸納了實驗過程中常用的實驗儀器設備和主要實驗試劑,介紹了研究和分析DFAFCs催化劑所使用的主要物理表征手段和電化學測試技術,描述了工作電極的制備過程。第三章PDDA協(xié)同下的CO還原法制備超小Pd納米晶/石墨烯催化劑及其甲酸氧化催化行為的研究石墨烯(Graphene)具有較高比表面積、導電性優(yōu)良和電化學穩(wěn)定的特點。本章采用PDDA修飾Graphene,并利用CO作為還原劑在其表面均勻沉積了平均粒徑為3.4 nm的Pd納米晶——Pd@PDDA-G催化劑。結合催化劑物理表征以及電化學測試技術分析,與商業(yè)化的Pd/C催化劑相比,Pd@PDDA-G催化劑展示出更高的電化學活性比表面積和標準交換電流密度、更低的電荷轉移電阻(Rct)以及更好的穩(wěn)定性,從而在作為DFAFCs陽極催化劑方面具有更廣闊的應用前景。我們認為,高導電性能的多孔結構載體Graphene與表面潔凈、超小且均勻分散的Pd納米晶協(xié)同催化作用是Pd@PDDA-G催化劑體現(xiàn)出優(yōu)良催化性能的重要原因,同時本章研究為電極表面納米結構催化劑的甲酸氧化催化反應提供了一些科學性見解。第四章多枝化Pd納米枝晶合成及其甲酸氧化催化行為研究采用一種簡易的方法制備了均勻分散且高度枝化的Pd納米枝晶(Pd-NDs)——獨特的多孔結構和粗糙的表面,并對該催化劑的甲酸氧化催化行為進行了研究。研究發(fā)現(xiàn):苯甲醇和甲酸的體積比在制備獨特納米結構的Pd-NDs催化劑中扮演者重要的角色,而聚乙烯吡咯烷酮(PVP)濃度則是調(diào)控Pd-NDs粒徑大小并實現(xiàn)催化劑尺寸可控的重要因素。通過電化學測試發(fā)現(xiàn),Pd-NDs/C催化劑展現(xiàn)出比Pd/C催化劑更高的峰電流密度、催化活性以及更好的穩(wěn)定性。本章工作中多枝化Pd納米枝晶合成條件溫和,操作簡單,重復性強,因此有利于大規(guī)模范圍的應用,同時該合成方法低毒環(huán)保,可以用于制備其它金屬催化劑。第五章結論和工作展望本章對論文進行了總結,并對未來研究的方向做了進一步的展望。
[Abstract]:The direct formic acid fuel cell (Direct formic acid fuel cells, DFAFCs) has the advantages of high energy conversion efficiency, safety and innocuity and environment friendly and so on. It has extensive application prospects in automobile power and portable power supply. However, the activity and stability of the anode Pd/C catalyst commonly used in DFAFCs are not good enough to restrict its commercialization. An important factor in development. The progress and depth of nanotechnology has developed an effective method for the design and preparation of high performance catalysts in the related scale. The homogeneous dispersed small particle size Pd nanoparticles exhibit higher electrochemical activity specific surface area while increasing the material utilization, while the special nano structure Pd catalyst has a rough surface. The porous structure usually has a large number of defects - providing a rich kink atom as a catalytic active site, which is conducive to the improvement of the kinetics of the electrode process during the oxidation of formic acid. However, the synthesis of Pd catalysts for high performance special nanostructures is still facing great challenges in basic research and techniques. The structure and morphology of the prepared catalysts were characterized by transmission electron microscope (TEM), scanning electron microscope (SEM), X ray diffractometer (XRD), X ray spectrometer (EDS), etc. by means of transmission electron microscope (TEM), and the structure and morphology of the prepared catalysts were characterized by means of circulation. The electrochemical behavior and properties were compared and analyzed by voltammetry (CV) and timing current method (I-T). The results showed that polydiallyl two methyl ammonium chloride (PDDA) assisted CO reduction in the preparation of homogeneous super small Pd nanocrystalline / graphene catalyst, because the porous structure carrier graphene was clean and ultra small. The uniformly dispersed Pd nanocrystals co catalyzed the oxidation of formic acid better than commercialized Pd/C catalysts. The polycrystalline Pd dendrites provided rich kinks and step atoms as active sites because of their highly branched and rough surfaces, and it had a unique porous structure and a high contact table. The area promotes the electrochemical kinetic process and presents some scientific views for the oxidation of formic acid at the same time that the oxidation behavior of formic acid is more excellent than the Pd/C catalyst. The content of this paper is divided into five chapters: the first chapter briefly summarizes the development process, principle, classification, performance and advantages of the fuel cell. The working principle of DFAFCs and the corresponding catalyst are introduced, and the preparation methods of some common catalysts are also outlined. Finally, the significance and main contents of this paper are discussed. The second chapter of the experiment design, material characterization and electrochemical testing technology summarizes the experimental instruments used in the experimental process. Preparation and main experimental reagents, the main physical characterization means and electrochemical testing techniques used for DFAFCs catalysts are introduced and analyzed. The preparation process of working electrodes is described. The preparation of ultra-small Pd nanocrystalline / graphene catalysts by the CO reduction method under the synergy of third chapter PDDA and the study of methenoic acid oxidation catalytic behavior of graphene (Graphene) It has high specific surface area, excellent electrical conductivity and electrochemical stability. This chapter uses PDDA to modify Graphene, and uses CO as a reducing agent to evenly deposit the Pd nanocrystalline - Pd@PDDA-G catalyst with an average particle size of 3.4 nm on its surface. It combines the physical characterization of the catalyst as well as the electrochemical test technology analysis, and the commercial Pd/C catalysis. The Pd@PDDA-G catalyst shows a higher electrochemical activity than the surface area and the standard exchange current density, lower charge transfer resistance (Rct) and better stability. Thus, it has a wider application prospect as a DFAFCs anode catalyst. We think that the porous structure carrier of high conductivity is Graphene and the surface. Clean, ultra-small and uniformly dispersed Pd nanocrystalline synergistic catalysis is an important reason for the excellent catalytic performance of Pd@PDDA-G catalyst. At the same time, this chapter provides some scientific opinions for the oxidation of formic acid on the surface of nano structure catalyst on the electrode surface. Fourth chapter the synthesis of polycrystalline Pd dendrites and the oxidation catalysis of formic acid A simple method was used to prepare a uniformly dispersed and highly branched Pd dendrite (Pd-NDs) - a unique porous structure and a rough surface, and the catalytic behavior of the formic acid in the catalyst was studied. The volume ratio of benzyl alcohol and formic acid was found in the Pd-NDs catalyst for the preparation of the unique nanostructure. The concentration of polyvinylpyrrolidone (PVP) is an important factor in regulating the size of Pd-NDs particles and realizing the controllable size of the catalyst. The electrochemical test shows that the Pd-NDs/C catalyst exhibits higher peak current density, catalytic activity and better stability than the Pd/C catalyst. In this chapter, the multi branched Pd Na The synthesis of rice dendrites is mild, simple in operation and strong in repeatability. Therefore, it is beneficial to large-scale application. At the same time, the synthetic method is low toxic and environmentally friendly and can be used in the preparation of other metal catalysts. The fifth chapter and the work prospect are summarized in this chapter, and the direction of future research is further prospected.
【學位授予單位】：西南大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：O643.36;TM911.4

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本文編號：1904440