| Summary: | 碩士 === 國立中央大學 === 材料科學與工程研究所 === 97 === 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.
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