提升觸媒利用率與效能是質子交換膜燃料電池的重要課題。目前燃料電池觸媒擔體多使用碳黑，但因可能形成孤島效應，導致觸媒利用率降低。若能製備規則多孔碳材為載體，有機會改善此一缺點。多孔碳具有高比表面積、高孔隙率與機械穩定性，適合作為燃料電池電極觸媒載體，其多孔結構能有效地區隔觸媒顆粒，避免觸媒聚集。 本研究主要以製作連續且規則性結構多孔碳作為陰極觸媒載體應用於燃料電池，提高觸媒利用率及加強電子傳遞。由於Pt-M/C合金觸媒的活性比純Pt/C觸媒高，利用摻雜技術製備Pt-M/C合金觸媒代替現有傳統純Pt/C觸媒來增加ORR活性，考量酸性操作環境，選擇Sn作為Pt-Sn/C合金觸媒材料，藉以降低鉑使用量，達到燃料電池生產成本降低之目標。 從實驗中發現，使用醇類還原法製備Pt-Sn/OPC觸媒，其觸媒分散性良好，粒徑維持在2.6 nm，且具有高比表面積與多孔結構的多孔碳能降低觸媒粒徑及抑制觸媒聚集現象。從XRD可知，Pt-Sn/OPC之Pt (111)晶面繞射峰為39.3o較Pt/C之Pt (111)晶面繞射峰為39.8o往低角度位移，此現象表示Sn原子摻雜成功，產生Pt-Sn合金相。經由電化學分析與長時間穩定性測試，Pt-Sn/OPC觸媒之活性均高於傳統純Pt/C觸媒。Pt-Sn/OPC觸媒具有良好的性能，有望成為PEMFC 陰極觸媒的替代材料。 How to increase catalyst utilization and activity are very important in PEMFC. Carbon black is widely used today as the catalyst support. Although current practice of using carbon black to support catalyst can enhance catalyst dispersion and catalytic activity, it suffers from loss of catalytic use due to occasional island formation. This can be prevented by using continuous catalyst support. Ordered porous carbon (OPC) is used as the catalyst support for fuel cell application due to its large surface area and continuous structure. We will prepare continuous and ordered structure of porous carbon as catalyst support for PEMFC to improve the catalyst utilization and enhance electron transfer. Pt-M alloy catalysts have higher activity than pure Pt catalysts. The noble metal, Sn, is a promising candidate to replace Pt not only reduces cost by lowering Pt loading but also increases ORR activity in acidic environment of fuel cell. Results show that PtSn/OPC as prepared has well dispersed PtSn nano particles, with an average particle size around 2.6 nm. Compared XRD patterns with pure Pt’s, the reflection peak associated with the Pt(111) of PtSn samples is slightly shifted from 39.8° to about 39.3°, indicating the formation of a solid solution involving the incorporation of Sn atoms into the lattice of Pt. The electrochemically active surface area of PtSn/OPC samples is found to be higher than that of Pt/C. During long-term stability, due to the confining effects of mesopores of OPC on Pt-Sn particles, the Pt-Sn/OPC catalyst exhibits better long-term durability than Pt/C. Therefore, the Pt-Sn/OPC catalyst is promising as a durable and robust cathode catalyst for PEMFCs.
