超臨界流體沉積法製備鉑基觸媒層

Preparation of Platinum-based Catalyst Layer by Supercritical Fluid Deposition

陳美吟(Mei-yin Chen)

指導教授 ： 葉華光

中原大學/理學院/化學研究所/碩士(2012年)

https://doi.org/10.6840/cycu201200895

摘要

本研究使用超臨界流體沉積法（SCFD）於氣體擴散層（GDL）上製備鉑基觸媒層，可應用於質子交換膜燃料電池（PEMFC）作為電極。良好的觸媒應具備奈米等級的尺寸，在基材上有高分散性並減少金屬團形成和降低實驗成本，而超臨界流體之表面張力極低，能滲入基材的微孔性物質中，對有機金屬前驅物有較高的溶解力，能提高觸媒的沉積速度及分散性。
研究初期尋找適合的熱還原方式和影響金屬薄膜形成的因子，並將實驗結果作為訂定二水準因子實驗設計的條件。實驗設計以Cu(acac)2作為金屬前驅物、GDL為基材，固定沉積條件，探討熱還原溫度、熱還原時間、甲醇添加等操作參數對金屬載量、分散度的影響，以建構SCFD法之實驗條件。最後進行SCFD法之最佳化，以Pt(acac)2為前驅物沉積在GDL上，實驗結果發現沉積時間會影響金屬在GDL上的緻密度；熱還原溫度和時間的增加，會使金屬粒徑有增加趨勢；當甲醇與前驅物添加量比例為1mL / 20mg時可得到最高的金屬載量，添加甲醇後之樣品金屬分佈均勻。研究最後以沉積條件80℃下6小時、熱還原條件250℃下4小時、甲醇添加量1mL / 20mg之條件為最佳條件，形成的鉑金屬顆粒分散性高、分佈均勻且團聚情形少，其鉑載量達0.276 mg / cm2，平均粒徑在11.5 ± 2.5 nm左右。

關鍵字

觸媒 ； 白金電極 ； 超臨界流體沉基法 ； 實驗設計

並列摘要

This research employs supercritical deposition (SCFD) for the preparation of platinum-based catalyst layer on a gas diffusion layer (GDL) which resembles an electrode in proton exchange membrane fuel cell (PEMFC). The common criteria for a good catalyst are a narrow nanoscale support, high dispersion on substrate, reduction of aggregation of metal particles, and low cost.
　　The effects of reaction factors (reduction temperature, time, and addition of methanol) on metal loading and dispersion on substrate were determined by factorial experimental design. The results showed that addition of methanol has significant effect on metal loading. Impregnation of platinum acetylacetonate (Pt (acac)2) into GDL substrate in supercritical carbon dioxide (scCO2) solutions indicates that metal compactness on substrate correlates with impregnation time, with Pt aggregation increase when thermal reduction time and temperature were increased. The optimization impregnation was carried out at 200◦C for 6 hours, followed by thermal reduction at 250◦C for 4 hours with addition of 1 mL methanol. Nanoscale Pt particles on GDL was successfully prepared with Pt loading of 0.276 mg/cm2 and an average particle size of 11.5 ± 2.5 nm.

並列關鍵字

Catalyst ； Experiment design ； Supercritical fluid deposition ； Pt-electrode

參考文獻

衣寶廉，燃料電池：原理與應用，五南出版社，2005。

Larminie, J., Dicks, A., Fuel cell systems explained, John Wiley & Son, Inc.,2000.

Gamburzev, S., Appley, A.J., Recent progress in performance improvement of the proton exchange membrane fuel cell (PEMFC), Journal of Power Sources, Vol. 107, pp. 5-12, 2002.

Bender, G., Zawodzinski, T.A., Saab, A.P., Fabrication of high precision PEFC membrane electrode assemblies, Journal of Power Sources, Vol. 12, pp. 114-117, 2003.

Gruber, D., Ponath, N., Müller, J., Lindstaedt, F., Sputter-deposited ultra-low catalyst loadings for PEM fuel cells, Journal of Power Sources, Vol. 150, pp. 67-72, 2005.