提高直接甲醇燃料電池陰極觸媒效能之研究

A Study of Promoting Performance of Cathode Catalyst for DMFC

薛家豪(Jia-Hao Syue)

指導教授 ： 林啟瑞 ； 蘇春熺

國立臺北科技大學/機電學院/製造科技研究所/碩士(2008年)

摘要

由於目前關於直接甲醇燃料電池觸媒之研究，多半集中於陽極觸媒對於直接甲醇燃料電池效率之影響，故本研究針對直接甲醇燃料電池陰極觸媒進行研究，以配合陽極觸媒改善直接甲醇燃料電池之效率。本研究係利用實驗方法探討不同陰極觸媒製程參數對於直接甲醇燃料電池效率之影響，首先使用氧化劑對奈米碳管進行表面改質處理以增加其表面官能基，其後使用含浸法製作直接甲醇燃料電池之陰極觸媒，並對其進行材料表面特性分析，最後將其製作成直接甲醇燃料電池進行效率測試，以探討不同陰極觸媒製程參數對於直接甲醇燃料電池效率之影響。研究中使用拉曼光譜分析奈米碳管ID/IG比之變化，推測其官能基變化；能量散佈光譜儀分析奈米碳管表面之元素種類及含量；穿透式電子顯微鏡分析奈米碳管上鉑金屬之顆粒大小及分散性；X光粉末繞射儀分析鉑金屬之結晶性並計算鉑金屬之顆粒大小與TEM分析之結果進行比較；燃料電池測試平台分析直接甲醇燃料電池之極化曲線及輸出功率。
奈米碳管氧化實驗結果顯示，奈米碳管表面之含氧官能基數目隨著奈米碳管之ID/IG比提高而增加；以改質奈米碳管還原Pt/CNTs觸媒之實驗結果顯示，以硫酸改質之奈米碳管還原之Pt/CNTs觸媒輸出功率密度0.87 mW/cm2為所有樣本中最高，其鉑金屬顆粒大小為7.24 nm，實驗結果同時顯示以硝酸改質奈米碳管，雖可提高直接甲醇燃料電池之輸出功率，但其提升效果有限；參數最佳化之結果顯示，經參數最佳化之Pt/CNTs觸媒其燃料電池最高輸出功率密度為0.93 mW/cm2，與僅進行奈米碳管改質參數最佳化之Pt/CNTs觸媒相較其最高功率提高7 ％；與僅進行鉑金屬還原參數最佳化之Pt/CNTs觸媒相較其最高功率提高102 ％。

關鍵字

直接甲醇燃料電池 ； 含浸法 ； 奈米碳管 ； 陰極觸媒

並列摘要

The study is based on experiment design to treat the relationship between process parameters of cathode catalyst and performance of direct methanol fuel cell. The experiments are divided into three parts. First, oxidants are used to oxidize carbon nanotubes to increase the surface functional groups. Second, impregnation method is used to process the cathode catalyst and then the material characters of the cathode catalyst are analyzed. Finally, by using the so-fabricated MEA to form a direct methanol fuel cell and then to analyze the performance for discussing the relation between the process parameters of cathode catalyst and performance of direct methanol fuel cell. In the study, Raman spectrum is used to analyze the ID/IG ratio of carbon nanotubes to calculate the charge of surface functional groups; EDS is used to analyze the kind and quantity of metal on the carbon nanotubes surface; TEM is used to analyze particle size and the disparity of Pt on the carbon nanotubes surface; XRD is used to analyze crystalline and particle size of Pt to compare with TEM analysis; A fuel cell test system is used to analyze the Polarization curve of the DMFC.
In the carbon nanotubes oxidization experiment, the result reveals that the surface functional groups increase with the ID/IG ratio of carbon tubes. In the oxidative carbon nanotubes reduction Pt/CNTs catalyst experiment, H2SO4 is applied to the oxidized carbon nanotubes for the Pt/CNTs catalyst reduction and the highest peak power density is readied, which is about 3.48 mW/cm2 and the particle size is 7.24 nm. From the result which is able to show that though using HNO3 oxidization carbon nanotubes can increase the power of DMFC, but the effect is limited. From the optimization experiment results, the peak power density of Pt/CNTs catalyst with parameter optimization is 3.72 mW, which increases about 7 % compared with Pt/CNTs catalyst that only optimized with oxidize carbon nanotubes. Also, the peak power increase 7 % in comparison with Pt/CNTs catalyst that is only optimized the reduction parameters increase 102 %.

並列關鍵字

Direct methanol fuel cell ； Impregnation ； Carbon nanotube ； Cathode catalyst

參考文獻

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