利用脈衝雷射沉積技術成長PEMFC鉑奈米顆粒觸媒

Growth of Pt nanoparticle for proton-exchange-membrane fuel cells by pulsed-laser deposition

林冠任(Guan-Ren Lin)

指導教授 ： 曾重仁

國立中央大學/工學院/機械工程學系/碩士(2014年)

摘要

本研究採用脈衝雷射沉積法(Pulsed-laser deposition method, PLD)
製備鉑奈米顆粒於電極上，透過改變背景氣體壓力控制鉑奈米顆粒，從XRD 估算鉑粒徑與比較電化學活性表面積，得知背景氣體壓力在800mTorr 為最佳工作點。之後控制雷射發數成長不同鉑擔載量，在組裝電池的測試中，應用於陽極鉑擔載量為24 μg cm-2 時在0.6 V 下的電流密度可達到1366 mA/cm2，優於商用(E-Tek) MEA 的性能，且因鉑擔載量大幅下降，陽極(Mass specific power density, MSPD)提升約9 倍。另外，陽極鉑擔載量為13 μg cm-2時在0.6 V 下的電流密度也有1032 mA/cm2，故陽極MSPD 高達47.61 kW/g。
使用PLD 製備的觸媒有較高的MSPD 的主要原因為，減少觸媒孤島效應的發生，而此效應在一般的商用觸媒容易發生，故從電池性能測試可以發現MSPD 比起商用觸媒有明顯的改善。針對表面結構觀察發現，鉑奈米顆粒具有分散性佳，且鉑顆粒大小可以控制在2-3 nm 左右，當鉑擔載量越高，鉑顆粒開始有聚集的現象，為MSPD 隨著鉑擔載量增加而下降的原因。而活性分析結果發現，氫吸附面積與ORR 活性隨鉑擔載量提高而下降，主要原因為顆粒聚集和顆粒尺寸的增加，而使得活性降低，大致上電化學活性測試與電池性能具有相同的趨勢。

關鍵字

脈衝雷射沉積法 ； 電化學活性表面積 ； 質量比功率密度 ； 質子交換膜燃料電池 ； 氧還原反應

並列摘要

Pulsed laser deposition (PLD) was used to prepare Pt nanoparticles on gas diffusion electrode by varying the Ar pressure in the dsposition chamber.
X-ray diffraction analysis and electrocatalytic activity of Pt nanoparticle indicate that the Ar pressure of 800 mTorr is the best operating point.The PLD catalysts was used at anode side of a polymer electrolyte membrane (PEM) fuel cell. With a Pt loading of 25 μg-Pt/cm2, current density
reaches 1366 mA/cm2 at 0.6 V, similar to commercial Pt/C at much higher Pt loading (200 μg-Pt/cm2). The mass specific power density(MSPD) increases about ten times as compared with commercial Pt/C. Even with lower Pt loading of 13 μg-Pt/cm2, the current density still have 1032 mA/cm2 .The
MSPD is 47.6 kW/g.
The primary reason that PLD catalysts show higher MSPD may be ascribed to reduced occurrence of island formation, which is common for traditional Pt/C catalysts.
TEM images indicate that the Pt nanoparticles have good dispersion. The size of the Pt nanoparticle is approximately 2-3 nm. Higher Pt loading causes Pt particles to aggregate. This is the main reason that MSPD decreases with increasing Pt loading. The electrochemical analysis found IV
electrochemical active surface area and ORR activity decrease with increasing platinum loading, due to Pt particle size increase and particle aggregation. In general, the trend of the electrochemical test result and fuel cell performance agree with each other.

並列關鍵字

Pulsed laser deposition ； PEM fuel cell ； Mass specific power density ； Electrochemical active surface area ； Oxygen reduction reaction

參考文獻

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