- 學位論文
有序的二氧化矽奈米管/Nafion複合膜之製備及在其質子交換膜燃料電池之應用
Preparation of ordered silica nanotubes/Nafion proton exchange composite membrane for PEMFC application
摘要
本研究成功的使用聚碳酸酯膜(polycarbonate membrane)作為模板，四乙氧基矽烷(TEOS)作為前驅液，以溶膠凝膠法(sol-gel method)合成，再經由高溫鍛燒移除Pluronic P123®及聚碳酸酯膜，製備出有序的二氧化矽奈米管(aSNT)及雜亂的二氧化矽奈米管(SNT)，其後將此材料經表面改質磺酸化，使其接枝上-SO3H，並以其作為填充物導入Nafion®質子交換膜中，應用於燃料電池，並探討其有序的二氧化矽奈米管之方向性，對單電池效果之影響。 由質子導電度結果得知， 含有3wt % SSNT的N/3SSNT膜有最好的導電度，在80 °C時，可達到(1.51×10-2 S cm-1)，另外有序的二氧化矽奈米管(N/aSNT)材料在80 °C時，其導電度也達到(1.17×10-2 S cm-1)，值得注意的是，此材料雖未經表面改質，但因有序的二氧化矽奈米管的形貌，有助於加速質子的傳遞，因質子傳遞的路徑都有序的朝同一方向。 此外，本研究所製備之複合膜應用在質子交換膜燃料電池(PEMFC)之效能測試顯示，在不同測試條件下以N/3SSNT複合膜為交換膜之FC-3之表現最為突出，在60 °C時，其功率密度可達到807 mW cm-2，電流密度2018 mA cm-2，顯示N/3SSNT為本研究中效能最好的交換膜，比以未含添加物之Nafion® 為交換膜之FC-0質子交換膜燃料電池的效能多出80.1 %。而以N/aSSNT(C)為交換膜之FC-8，在60 °C時，可達到功率密度668 mW cm-2，電流密度1670 mA cm-2呈現有序形貌中最好的效能，比FC-0的效能多出49.8 %。本研究開啟製備有序形貌二氧化矽奈米管，作為質子交換膜添加物之可行性，日後若在質子交換膜製備上技術更精進必能對PEMFC之應用很有貢獻。
並列摘要
In this study, the ordered, one-dimensional silica nanotube (SNT) that is perpendicular to the substrate has been synthesized by deposition of the prehydrolyzed silica sol with surfactant into the cylindrical pores of polycarbonate (PC) membranes. The PC membrane, which is used as a template, and the surfactant are removed by the calcination process. Then SNT was sulfonated to prepare the sulfonated silica nanotube (SSNT). The as-prepared silica nanotubes were then separately used as fillers to obtain the corresponding composite membranes, N/1SSNT, N/2SSNT, N/3SSNT, N/4SSNT, N/aSNT, and N/aSSNT by dispersing in Nafion®. The performances of the proton exchange membrane fuel cells measured with the as-prepared composite membranes were studied and compared to that with recast Nafion® membrane (RN). The as-prepared ordered SNT (aSNT), ordered SSNT (aSSNT), and disordered SSNT nanomaterials were characterized by WXRD, FTIR, SEM, TEM, BET, IEC, and SEM-EDS. The properties of the composite membranes were investigated by their proton conductivity and water uptake. The results showed that compared with the recast Nafion® membrane, the highest water uptake of the composite membrane was significantly enhanced to 43.5±5.0 wt.%. It was also found that compared to that of RN, the proton conductivity and ion exchange capacity of all the composite membranes were increased. The as-prepared composite membrane exhibits good water retention due to the hygroscopic property of the silica nanotubes. Furthermore, aSSNT in the composite membrane is anticipated to provide the continuous one-dimensional channels to construct faster pathways for the protons to transport between the electrodes. The results of the performances of PEMFC indicates that the power density of the PEMFC fabricated with the aSSNT-based FC, FC-8, at 60 °C under the humidified condition is approximately 49.8 % higher than that with RN. In addition, the performances of the PEMFCs with various amount of the disordered SSNT in the Nafion® composite membrane were also tested with H2/O2 gases. The best performance single cell at 60 °C under the humidified condition was obtained from FC-3, the PEMFC fabricated with 3wt.% of SSNT, N/3SSNT. Its power density was 807 mW cm-2 and was 80.1 % higher than RN. This study opened the possibility of using aligned silica nanotube that perpendicular to the electrodes to guide the proton transport. Further improvement in fabrication of the membrane will make aSSNT potential filler for PEM.