- 學位論文
以鎳取代白金作為DMFC之膜電極組觸媒的比較研究
The Study of Ni catalysts for replacing Pt catalysts in MEA of DMFC
摘要
本研究是使用含浸法(Impregnation Method)製備Pt/CNT和Ni/CNT及使用奈米鎳粉(Nickel Powder)做為直接甲醇燃料電池(DMFC)的陰陽極觸媒。將常使用的觸媒載體碳黑（Vulcan XC-72）以奈米碳管取代，此因奈米碳管擁有比碳黑更高的比表面積（specific surface area），範圍約在50~1315m2/g之間變化，而碳黑（Vulcan XC-72）約250m2/g。白金觸媒的製備是使用三次含浸法及乙二醇還原法，以乙二醇還原法所製備之白金觸媒較好，其平均粒徑為8.9 nm，且依此法所製備之觸媒重現性佳。對乙二醇還原法所製備之白金觸媒數量及粒徑尺寸進行統計及分析，可得知碳管管徑大上的觸媒其粒徑大小分布較廣,且各個碳管上之觸媒平均粒徑隨著管徑變大而變大。鎳觸媒部分則是購買平均粒徑35 nm的鎳粉，與奈米碳管混合作為電極觸媒用。當陽極為鎳，陰極為白金時，無穩定電流產生。當陽極為白金，陰極為鎳時，在0.1 V時有0.125 mA/cm2的穩定電流產生。在鎳觸媒部分加入Au做改善，結果在0.1 V時，電流密度提昇至0.375 mA/cm2，在電位部分也提昇至0.3 V，電流密度為0.025 mA/cm2，在量測電池性能的過程中發現，電池效能會隨著量測的次數增加而有一個最佳值，之後電池效能又會隨著量測次數的增加而遞減，所以我做了一次連續量測60次的實驗，每10次取一個平均值來觀察及比較，結果發現，在31~40次的平均值中，其電池效能最好，所以若要得知自製之MEA的真正效能，可使用多次量測法找出最好且真正的I-V性能曲線圖。
並列摘要
This research is based on Impregnation Method which applies Pt/CNT、Ni/CNT and apply nickel powder as catalyst for anode/cathode. By substitute CNTs for Vulcan XC-72 for it has a higher specific surface area which ranges from 50~1315 m2/g. However, for Vulcan XC-72 is only about 250 m2/g. we use Three times impregnation and the polyol reduction process to prepare Platinum catalyst. For the preparation of the polyol reduction process can reach a better efficient which has the average particle diameter about 8.9 nm. Beside, the ability of preparation to reach the same result is very high. To analysis the particle size and the amount of platinum catalyst, we can acknowledge that the dispersion of catalyst on the CNTs diameter is very wide. Futhermore, the average catalyst particle on each CNTs is getting larger as the diameter goes up. Ni catalyst is the nickel powder which has the average particle diameter of 35 nm which is used to mix with CNTs as electrode catalyst. When we apply Ni as anode platinum as cathode, there is no stable current occur. On the other hand, when we apply platinum as anode and Ni as cathode, there is a stable current which is about 0.125 mA/cm2 occurs at 0.1 V. when we add Au to improve, the current density raise up to 0.375 mA/cm2 at 0.1 V. For the voltage is rising up to 0.3 V, the current density reaches0.025 mA/cm2. During the process of measuring the ability of battery, the battery efficient reaches a best value as the measuring time increase. Afterwards, the battery efficient reduces as the measuring time increases. For a 60times measuring, the average value of battery reaches a best result at measuring times of 31-40. If we really need to know the true efficient of MEA, we can find the I-V curve through rising up the times measurement.