本文關鍵詞：質子交換膜燃料電池膜電極及催化劑的研究　出處：《天津大學》2014年博士論文　論文類型：學位論文

  更多相關文章： 質子交換膜燃料電池 膜電極 電場定向 電催化劑 鉑納米顆粒 石墨納米片

【摘要】：質子交換膜燃料電池（PEMFC）具有清潔、高效、功率密度高、啟動快等優(yōu)點，在電動汽車、便攜式和分布式電源設備等領域具有廣闊的應用前景。但PEMFC膜電極的高成本和低穩(wěn)定性嚴重地制約了其大規(guī)模商業(yè)化應用。本文從膜電極的制備、催化層的結構取向優(yōu)化、高催化活性和高穩(wěn)定性Pt催化劑的制備等方面對PEMFC進行了研究。 提出了一種新的膜電極制備方法：使稀催化劑“墨水”直接在氣體擴散層上干燥制備出氣體擴散電極，然后再與膜熱壓制得膜電極。該方法制備過程簡單，不需要特殊的儀器設備，催化層中的Pt載量能夠較為精確地控制，具有相同制備參數的膜電極，其放電電流-電壓曲線和功率密度曲線基本重合，實驗具有很好的重復性。催化層中的Nafion含量為30-40wt%時，電池的最大功率密度可達900mW/cm2。 利用電場的作用制備了結構取向的Pt/CNTs（Pt/碳納米管）催化層。在Pt/CNTs催化劑“墨水”干燥過程中施加垂直向外電場，使CNTs載體沿著電場的方向定向排列，有利于提高催化層中Pt的利用效率、降低膜電極的內阻、促進反應氣體的擴散和反應生成的液態(tài)水的及時排出。與無取向結構的Pt/CNTs催化層相比，CNTs載體定向排列的催化層具有高出約30%的電池峰功率密度。 以耐腐蝕、導電性好、比表面積高、廉價易得的石墨納米片（GNPs）為載體制備了Pt/GNPs催化劑。針對GNPs表面的化學惰性，利用芳香環(huán)π-π堆積的原理使1-芘甲酸吸附在GNPs的表面并為Pt提供成核點，，可以使沉積在GNPs表面的Pt納米顆粒具有約2-3nm的均一尺寸，且空間分布均勻。通過1-芘甲酸對GNPs進行非共價修飾，所制備的Pt/GNPs催化劑具有較高的電化學比表面積和較好的電化學穩(wěn)定性。 使用一系列含不同苯環(huán)數和不同官能團的修飾物研究了修飾物與GNPs的π-π堆積作用力和其官能團對Pt在GNPs表面沉積的影響，并通過改變催化劑的制備條件研究了修飾物在Pt沉積過程中的作用機理。結果顯示：修飾物與GNPs的π-π作用力較強且其官能團能夠電離時才對Pt的沉積具有明顯的輔助作用，另外，修飾物的不同不影響Pt納米顆粒的晶體結構和催化劑的電化學穩(wěn)定性。
[Abstract]:Proton exchange membrane fuel cell (PEMFC) has the advantages of cleanness, high efficiency, high power density, fast start and so on, in electric vehicles. Portable and distributed power generation devices and other fields have broad application prospects, but the high cost and low stability of PEMFC membrane electrode seriously restrict its large-scale commercial application. The structure and orientation of the catalyst layer, the preparation of Pt catalyst with high catalytic activity and high stability were studied in this paper. A new preparation method of membrane electrode is proposed: the thin catalyst "ink" is used to prepare the gas diffusion electrode directly on the gas diffusion layer, and then the membrane electrode is prepared by hot pressing with the membrane. The preparation process is simple. The Pt load in the catalyst layer can be controlled accurately without special equipment. The discharge current-voltage curve and the power density curve of the membrane electrode with the same preparation parameters basically coincide. When the Nafion content in the catalyst layer is 30-40 wt%, the maximum power density of the cell can reach 900mW / cm ~ 2. The structure oriented Pt / CNT / carbon nanotube (CNT / CNT / CNT nanotube) catalyst layer was prepared by the electric field. The vertical electric field was applied during the drying process of the Pt/CNTs catalyst "ink". The orientation of CNTs carriers along the direction of electric field can improve the utilization efficiency of Pt in the catalyst layer and reduce the internal resistance of the membrane electrode. Promote the diffusion of the reaction gas and the timely discharge of the liquid water produced by the reaction, compared with the non-oriented structure of the Pt/CNTs catalytic layer. The CNTs carrier oriented catalytic layer has a peak power density of about 30%. The Pt/GNPs catalyst was prepared on the basis of high corrosion resistance, good electrical conductivity, high specific surface area and cheap and easy to obtain graphite nanoparticles. Based on the principle of aromatic ring 蟺-蟺 stacking, 1-pyrene formic acid is adsorbed on the surface of GNPs and provides nucleation point for Pt. The Pt nanoparticles deposited on the surface of GNPs have a uniform size of about 2-3 nm and uniform spatial distribution. GNPs was modified by 1-pyrene formic acid. The prepared Pt/GNPs catalyst has high electrochemical specific surface area and good electrochemical stability. The 蟺-蟺 stacking force of GNPs and the effect of functional groups on Pt deposition on the surface of GNPs were studied by using a series of modifiers containing different benzene rings and different functional groups. The mechanism of the modification in Pt deposition was studied by changing the preparation conditions of the catalyst. The results showed that:. When the 蟺-蟺 interaction force between the modifier and the GNPs is strong and its functional group can ionize, it has obvious auxiliary effect on Pt deposition. In addition, the crystal structure of Pt nanoparticles and the electrochemical stability of the catalyst were not affected by the modification.
【學位授予單位】：天津大學
【學位級別】：博士
【學位授予年份】：2014
【分類號】：TM911.4;O643.36

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本文編號：1417529