單電流脈衝電鍍鉑於奈米碳管/碳之電氧化研究

Single Current Pulse Plating Platinum on Carbon Nanotubes/C for Electrochemical Oxidation

侯仁健(Ren-Jian Hou)

指導教授 ： 黃進益

國立臺北科技大學/工程學院/化學工程所/碩士(2006年)

摘要

質子交換膜(PEM)燃料電池陰極與陽極的半反應需藉助鉑觸媒來降低活化能以催化電化學反應。而觸媒設計方向為提高與活性物質的接觸機率，使電催化性能增加，催化劑用量減少，降低電極成本。本實驗特以導電性與表面積較佳的奈米碳管(CNTs)為載體，使用可產生更緻密鍍層的單電流脈衝電鍍方式，控制脈衝的通電流密度、通斷電流時間及觸媒附載量，製備高活性的奈米鉑觸媒。
於0.01M H2PtCl6、1M HCl和1.25M CH3OH鍍液中，溫度25℃，控制不同的單電流脈衝參數：脈衝電流密度ip=20、40、60、80、100、120、140、160、180、200mA/cm2；通電流時間ton=0.05s、0.1s、0.15s、0.2s；斷電流時間toff=0.1s、0.3s、0.5s、0.7s、0.9s；通電庫侖量=2、4、6、8C/cm2。將各參數組合所鍍出之電極於0.5M硫酸及1M甲醇中經循環伏安法，觀察其電氧化情形。發現脈衝參數控制在ip=100mA/cm2、ton/toff=0.1s/0.5s、通電量6C/cm2時，不論是氫的脫附或甲醇的氧化，該電極觸媒活性表現均最佳。進一步由SEM觀察，該參數所鍍出的鉑觸媒顆粒大小約為50~80nm，而且分佈較均勻。

關鍵字

單電流脈衝電鍍 ； 鉑觸媒 ； 奈米碳管

並列摘要

The proton exchange membrane (PEM) fuel cell both of its cathode and anode half reaction must use the platinum catalyst to reduce the activation energy. The principle of catalyst design depends on the enhancement of contacting probability of the active material, the increasing of electricity catalysis performance, reduction of catalyst amount. In this way we can get a lower cost of the electrode. In order to enhance the platinum catalyst exposed ratio, we usually choose small particle with good electric conductivity, and choose the catalyst support with the character of anticorrosion. We use carbon nanotubes as the support with the more compacting coating layer single current pulse plating way in the experimental because of it’s better conductivity and surface area. By controlling the pulse current density, pulse frequency and the catalyst loading capacity, the nanostructured platinum catalyst can be obtained.
In 0.01M H2PtCl6, 1M HCl, 1.25M CH3OH solution, controlling the different single current pulse parameters can make the platinum catalyst. The pulse current density ip is in the range of 20 to 200 mA/cm2. The pulse frequency ton/toff is in the range of 0.05s、0.1s、0.15s、0.2s/0.1s、0.3s、0.5s、0.7s、0.9s. The catalyst loading capacity is in the range of 2 to 8 C/cm2. We use the CV method for analysis with different electrode plates obtained within various combination of parameters in 0.5M sulfuric acid and 1M methanol. In this way, we can get the optimum parameters which are ip = 100mA/cm2, ton/toff = 0.1s/0.5s, and loading capacity 6C/cm2. This result is suitable for both the hydrogen adsorption and the methanol oxidation. By SEM, we can observe the uniform structure and the size of the platinum catalyst. The particle size is about 50~80nm.

並列關鍵字

single current pulse plating ； platinum catalyst ； carbon nanotubes

參考文獻

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