目前應用於直接甲醇燃料電池最有效率的觸媒為鉑觸媒，包含陽極與陰極觸媒，主要原因是鉑對陽極甲醇的催化氧化及陰極氧分子還原反應，顯示出較高的活性，且鉑在酸性介質中有較高的穩定性及耐腐蝕性。而其他金屬雖然也可以催化甲醇的氧化反應，但性能和穩定性都不如鉑。然而鉑金屬價格昂貴，造成直接燃料電池的成本大大的提高，所以尋找較廉價的觸媒來替代鉑金屬是讓直接甲醇燃料電池能商業化的重要課題。使用鉑金屬當陰極觸媒還有甲醇會從陽極滲透到陰極的問題，甲醇滲透到陰極會造成混合電位及鉑金屬的活性中心被毒化這二種問題。對於陰極觸媒，尋求對氧分子還原反應有高活性且廉價的非鉑金屬觸媒是讓直接甲醇燃料電池能商業化的重點之一。 本論文探討利用鈀金屬來代替鉑金屬作為直接甲醇燃料電池陰極觸媒主要元素的可能性，並加入鈷當作第二金屬來形成二元合金鈀鈷觸媒以提升鈀的活性，並嘗試利用金屬鎢、鉬、金與鈀鈷觸媒形成三元合金觸媒，探討製備方法、活化方法及觸媒配製對氧分子還原反應及甲醇毒化的影響。利用旋轉圓盤電極和循環伏安法來判斷觸媒的活性。結果顯示鈀鈷系列觸媒有好的抗甲醇毒化能力。不論在有甲醇或無甲醇的環境下，觸媒對於氧分子還原反應的活性順序：鈀鈷鉬觸媒>鈀鈷金觸媒、鈀鈷鎢觸媒>鈀鈷觸媒。此外，所有鈀鈷系列觸媒在有甲醇的環境下的活性表現皆優於商用觸媒JM13100。另外使用醋酸鈀當鈀的前驅物製備的鈀鈷觸媒活性優於使用氯化鈀當鈀的前驅物製備的鈀鈷觸媒。 Platinum is the most effective electrocatalysts for use in Direct Methanol Fuel Cell (DMFC), both anode and cathode, because of its’ high catalytic activity for methanol oxidation and oxygen reduction reactions (ORR). Another advantage for using platinum is it has very high stability and good corrosion resistant under acidic operating medium. Even though other metals have similar activity capabilities but fail to perform in acidic condition. However, platinum is too expensive for use in DMFC and finding an alternative much cheaper catalyst is desirable towards the realization of DMFC. Another problem in using platinum at the cathode is the methanol crossover problem. Methanol crossover to the cathode created both over-potential and active site poisoning problems when Pt is used. The search for more active and less expensive non-platinum based catalysts for oxygen reduction reaction (ORR) is one of the most important issues towards the commercialization of DMFC. This thesis explores the possibility of using palladium, instead of platinum, as the basic component of the DMFC cathode catalyst. In order to boost the performance of Pd, Co was added to form a binary catalyst (PdCo/C). Furthermore, ternary PdCoW, PdCoAu and PdCoMo catalysts were also studied. The effect of preparation method, activation method and catalyst formulations towards ORR activity and methanol tolerance were explored in this thesis. Catalyst performance were studied using Rotating Disk Electrode (RDE) and Cyclic Voltammetry (CV). Results in this study revealed that PdCo based catalyst have good tolerance in methanol. The ORR activity, with and without added methanol, decreases in the following order: PdCoMo/C > PdCoAu~PdCoW > PdCo. Futhermore, all PdCo based catalysts have higher activity than commercial Johnson Matthey Pt/C catalysts in the presence of methanol. Catalysts prepared with Pd(CH3CO2)2 as the Pd precursor have better activity over PdCl2 precursor.
