以原子層沈積製備白金觸媒應用於氫氧質子交換膜燃料電池

Atomic Layer Deposition of Platinum Catalyst in Hydrogen and Oxygen Proton Exchange Membrane Fuel Cell

劉玨(Chueh Liu)

指導教授 ： 彭宗平

國立清華大學/工學院/材料科學工程學系/碩士(2007年)

摘要

隨著能源危機與污染問題日益嚴重，燃料電池成為極有潛力的替代能源之一，但低觸媒活性與使用率，導致其成本過高；然而不同製程可改變觸媒活性與使用率，故期盼原子層沈積能提高此兩種特性。
用原子層沈積白金在不同基板上，包含碳布、碳黑或碳管塗佈的碳布，以作為質子交換膜燃料電池觸媒使用。本實驗以顆粒尺寸來探討白金原子層沈積在矽基板上的自我限制行為，以及顆粒尺寸與循環數的比例關係。藉由掃瞄電子顯微鏡影像證實了這兩個性質，也觀察到基板效應：白金不能沈積在未經酸處理的碳布，也不能沈積在有較高鐵氟龍含量的碳黑或碳管塗佈的碳布上；然而，因為表面官能基的改變，白金可以沈積在經過酸處理的碳布，以及在較低鐵氟龍含量的碳黑或碳管塗佈的碳布上。
比較不同膜電極組的效能測試，對陽極與陰極相同的膜電極組，E-TEK商用電極表現出最大的功率密度(W/cm2)，然而以原子層沈積白金一百循環的碳布電極有最低的白金功率密度(gPt/kW: 每千瓦之白金克數)。在不同陽極，但陰極都是E-TEK商用電極的膜電極組中，陽極是以原子層沈積白金一百循環於碳管塗佈碳布的膜電極組展現了最好的白金功率密度，卻仍有與E-TEK商用電極相似的功率密度。

關鍵字

原子層沉積 ； 燃料電池 ； 氫氣 ； 氧氣 ； 質子交換膜

並列摘要

With the increasing threats of energy crisis and pollutions, fuel cell has become one of the most prospective substitute energies, but low catalyst activity and utilization results in high cost; however different preparation methods can change catalyst activity and utilization, so it’s expected atomic layer deposition can increase these two properties.
Atomic layer deposition (ALD) is used to deposit Pt as catalyst of proton exchange membrane fuel cell catalyst on different substrates, including carbon cloth, carbon black powders or carbon nanotubes (CNT) coated on carbon cloth. In this experiment, Particle size is used to discuss self-limiting behavior and proportionality between particle size and cycle numbers of ALD of Pt on Si substrate. Both of the two characteristics are verified by SEM images. Substrate effects are also observed: Pt can not deposit on carbon cloth without acid treatment, and can not deposit on carbon black powder or CNT coated carbon cloth with higher concentration of PTFE addition; however, because of the change of the surface functional groups, for carbon cloth with acid treatment and carbon black powder or CNT coated carbon cloth with lower concentration of PTFE addition, Pt can deposit on them.
Performance tests of different membrane electrode assemblies (MEAs) are compared. For the MEAs of the same anode and cathode, as received E-TEK electrode shows the largest power density (W/cm2), while the electrode of carbon cloth with ALD of Pt for 100 cycles has the lowest Pt specific power density (gPt/kW: gram of Pt per kilowattage). For the MEAs of different anodes but cathodes are all as received E-TEK electrodes, anode of ALD of Pt on CNT coated carbon cloth for 100 cycles shows the best Pt specific power density, while it still has similar power density to E-TEK electrode.

並列關鍵字

Atomic layer deposition ； fuel cell ； hydrogen ； oxygen ； proton exchange membrane

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