由於能源危機以及環境保護的考量，高能量效率以及零排放的質子交換膜燃料電池系統(PEMFC)已成為一具有潛力的能源裝置。然而，因為陰極氧氣還原反應性不佳、以及白金觸媒價格相對偏高等缺點，許多科學家正致力於製備高活性的白金觸媒。 本研究以金的合金化以及氧化鈰的添加改質陰極白金觸媒，以應用於氧還原反應。第一部分製備金-白金觸媒，以金的合金化改質白金，研究不同劑量比的金-白金合金其觸媒催化性質。第二部份將金白金催化劑添加氧化鈰進行修飾，並探討不同劑量比的添加對於氧還原反應之活性。所研製的觸媒，其結構、表面物種及電催化活性分別利用X光繞射分析儀、程式溫度還原系統和旋轉盤電極分析鑑定。研究結果發現白金和金的合金修飾了催化劑的親氧力，氧化鈰的添加則提升了合金在碳上的分散度，增加白金的表面偏析，並且也降低了粒徑。相較於商用白金催化劑，在白金與金1：1的催化劑中添加15 %氧化鈰之電化學活性最佳，此觸媒是以白金為主的合金表面並具有適當的表面親氧力，這兩個因素能夠有效的提升觸媒的電化學活性。 Because of energy crisis and environmental protection, proton exchange membrane fuel cells (PEMFC) with zero emission and high energy efficiency have become a potential energy device. However, because of the sluggish oxygen reduction reaction (ORR) in cathodes and expensive Pt, many efforts have been done to develop Pt cathode catalysts with high ORR activity. This study focused on the preparation and modification of the cathode Pt catalysts. A combined effect of alloying with Au and modifying with CeO2 on the ORR activity was studied. In the first part, Pt has been alloyed with different amounts of Au and investigated their ORR activity. In the second part, different amounts of CeO2 has been added in the Pt-Au/C for the enhancement of ORR. The structure, surface species, and electro-catalytic activities of prepared alloy catalysts were characterized by X-ray diffraction (XRD), temperature programmed reduction (TPR), and rotating disc electrode (RDE) technique, respectively. It was observed that the alloying with Au modified the oxophilicity of Pt-Au alloy catalysts, while the addition of CeO2 decreased the particle sizes, increased the dispersion of alloy nanoparticles and enhanced the surface segregation of Pt. The ORR activity of Pt50Au50/C alloy catalyst with a promotion of 15 % CeO2 was enhanced significantly in comparison to the commercial Pt/C catalyst within the mixed kinetic-diffusion control region. The enhancement of Pt50Au50/Ce15C was attributed to the formation of an alloy surface, having a moderate oxophilicity and a Pt-related surface species.