本文選題：直接甲醇燃料電池　切入點：陽極催化劑　出處：《華南理工大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：直接甲醇燃料電池,是基于質(zhì)子交換膜燃料電池技術(shù)的低溫電池。甲醇直接進入燃料電池,不需要經(jīng)過重整轉(zhuǎn)換成氫的中間步驟。近來,由于直接甲醇燃料電池技術(shù)相對較為成熟且燃料來源豐富、儲存安全,直接甲醇燃料電池研發(fā)引起了廣泛關(guān)注。但真正實現(xiàn)商業(yè)化還是有較多的困難,催化劑技術(shù)即是其核心問題之一。本文以高活性、高穩(wěn)定性低溫燃料電池催化劑為目標,首先探索更優(yōu)化的金屬納米粒子制備方法,再制備出性能優(yōu)異的復(fù)合載體,之后利用所制備復(fù)合載體及Pt NPs制備40wt.%載量的催化劑,并對此過程進行深入研究。(1)當不使用高分子保護性試劑時,由于Oswald熟化作用,Pt納米粒子(3nm)很容易發(fā)生聚結(jié)。但使用包覆性試劑時,又會遮擋Pt NPs的活性位,導(dǎo)致燃料電池催化劑活性不高。在本文中,我們開發(fā)了一種無機鹽輔助檸檬酸還原法制備高分散和高穩(wěn)定性Pt溶膠(2nm)的方法。添加無機鹽后(在Pt NPs周圍形成厚的雙電層,穩(wěn)定Pt溶膠)可顯著減少檸檬酸的使用量(Cyt3-/Pt4+=1:1),因此不再需要后續(xù)加熱去除碳載鉑催化劑表面過量檸檬酸的操作。本文中借助Zeta電位、TEM測試和開路電位來表征Pt溶膠穩(wěn)定性實屬先例。所制得的Pt/C催化劑相比商業(yè)Pt/C催化劑有更高的甲醇氧化(以此反應(yīng)作比照反應(yīng))活性。單獨制備帶正電的Ru納米粒子和帶負電的Pt納米粒子,在室溫下混合后,通過靜電自組裝成結(jié)構(gòu)規(guī)整的PtxRuy納米粒子。在所得催化劑PtxRuy/C中,CO溶出伏安的起始氧化電位和峰電位與Pt/Ru比值密切關(guān)聯(lián),這可能是Pt和Ru間不同的組裝模式造成了不同的Pt、Ru粒子間距。Pt3Ru1/C的甲醇氧化質(zhì)量比活性比商業(yè)Pt Ru/C催化劑的高112%。(2)為了改善電催化劑載體穩(wěn)定性的問題,將納米級Ti O2、乙酸鈷和碳粉浸漬混合,在900℃還原性氣氛中處理,當混合物中的乙酸鈷高溫分解后即生成復(fù)合載體,經(jīng)XRD衍射分析得知組分為Ti O2-Co3O4-C(標記為CS)。通過計時電流測試,這種復(fù)合載體相比普通的炭黑在酸性條件下顯示出了更強的抗腐蝕性或穩(wěn)定性。利用該復(fù)合載體制備40.3wt.%的Pt/CS質(zhì)子交換膜燃料電池催化劑,在0.5M硫酸溶液中進行的加速穩(wěn)定性測試(AST)中顯示,Pt/CS的ECSA在測試完后剩27.9%,而Pt/XC-72(39.5wt.%)的ECSA剩8.4%。另外經(jīng)AST后TEM照片也可進一步證實Pt/CS有更強的抗Pt納米粒子聚結(jié)的能力。在0.5M CH3OH和0.5M H2SO4溶液中測試甲醇氧化性能顯示,相比于Pt/C,Pt/CS有更高的質(zhì)量比活性和更慢的活性衰減速率。
[Abstract]:Direct methanol fuel cells are cryogenic cells based on proton exchange membrane fuel cell technology. Methanol enters the fuel cell directly without the intermediate steps of reforming to hydrogen. Because the technology of direct methanol fuel cell is relatively mature, the fuel source is abundant and the storage is safe, the research and development of direct methanol fuel cell has attracted wide attention. However, there are still many difficulties to realize the commercialization of direct methanol fuel cell. The catalyst technology is one of its core problems. In this paper, the high activity, high stability and low temperature fuel cell catalyst is taken as the target. Firstly, the more optimized preparation method of metal nanoparticles is explored, and then the excellent composite support is prepared. After that, the catalyst with 40wt.% loading was prepared by using the prepared composite support and Pt NPs, and the process was studied deeply when the polymer protective reagent was not used. Due to the maturation of Oswald, Pt nanoparticles can easily coalesce. However, the active sites of Pt NPs will be blocked when the coated reagent is used, which leads to the low activity of the fuel cell catalyst. We have developed an inorganic salt-assisted citric acid reduction method for the preparation of highly dispersed and highly stable Pt sols (2nm). Stabilization of Pt sol can significantly reduce the amount of citric acid used by Cyt _ 3-P _ t _ 4 / 1: 1, so the operation of removing excess citric acid on the surface of carbon-supported platinum catalyst is no longer needed. In this paper, Zeta potential Tem and open-circuit potential are used to characterize Pt dissolution. The stability of the colloid is a precedent. The prepared Pt/C catalyst has higher methanol oxidation activity than commercial Pt/C catalyst (the reaction is compared to the reaction). The Ru nanoparticles with positive charge and Pt nanoparticles with negative charge are prepared separately. After mixing at room temperature, the structured PtxRuy nanoparticles were self-assembled by electrostatic self-assembly. The initial oxidation potential and peak potential of CO stripping voltammetry in the obtained catalyst PtxRuy/C were closely related to the Pt/Ru ratio. It is possible that the different assembly modes between Pt and Ru result in the difference of PtN Ru particle spacing. Pt3Ru1C has higher methanol oxidation mass activity than commercial Pt Ru/C catalyst.) in order to improve the stability of electrocatalyst support, The nano-TiO _ 2, cobalt acetate and carbon powder were impregnated and treated in a reductive atmosphere at 900 鈩，

本文編號：1564876