- 學位論文
微波輔助合成Pt/SiO2及其在自增濕質子交換膜燃料電池之應用與性質
Microwave-assisted Synthesis of Silica Supported Pt Nanoparticle for Self-humidifying Proton Exchange Membrane Fuel Cell
摘要
本研究用溶膠-凝膠法以不同模板，製備出不同孔洞型態之中孔洞二氧化矽，M41及AG。利用微波輔助法將Pt還原至M41及AG中，製備出二氧化矽支撐之鉑金屬催化劑PM41及PAG。再將PM41及PAG分別與Nafion 全氟磺酸化高分子混掺，製備自增濕質子交換膜N/PM41及N/PAG，探討這些複合膜之各項性能及其在燃料電池上之應用。 由XRD、TEM及孔洞表面積分析，所製備二氧化矽及鉑金屬催化劑粉體之結構、表面積、孔洞特性，及Pt晶粒大小之差異。此外亦探討添加二氧化矽及鉑金屬催化劑對質子傳遞之能力、含水率及觸媒分散之效應，及其對複合膜性質之影響。結果顯示，在複合膜之含水率(Water uptake)方面，添加無機氧化物之填充物含水率均有明顯提升，最高含水率可高達48.8wt.%，比市售之N212高出60%。導電度方面，因含水率之提升，複合膜之導電度亦有效提升。 此外，本研究製備之複合膜，應用在質子交換膜燃料電池(PEMFC)之性能測試顯示，操作氣體為H2(g)/O2(g)，在TH2/Tcell/TO2 =80/50/65℃加濕條件下，電壓為0.4V 時，最佳之複合膜組裝之PEMFC 效能功率密度達1104 mW/cm2，電流密度2760 mA/cm2，約比市售之N212 膜PEMFC高出72%；而在Tcell = 50℃不加濕條件下，電壓為0.4V 時，電流密度達2360 mA/cm2，相當於功率密度913 mW/cm2，其輸出功率比市售之N212約高出4.9倍之多。此結果明顯顯示所製備之複合膜，具有應用於攜帶式電源供應器之潛力。
並列摘要
In this study, different templets were used to prepare the mesoporous silicas with different morphology (M41 and AG) by the sol-gel process. the as-prepared silicas were then microwave-assisted synthesized the silica supported Pt nanoparticles, PM41 and PAG. PM41 and PAG were used, separately, as a filler to produce the uniform self-humidifying composite membranes, N/PM41 and N/PAG, by blending with the Nafion matrix. The performances of the proton exchange membrane fuel cells fabricated with the as-prepared composite membranes were investigated and compared to that with the recast Nafion membrane ( RN ) and the commercial Nafion membrane ( N212 ). The morphologies of the silicas and the silica-supported Pt prepared were characterized by XRD, TEM and BET measurements. The properties of the composite membranes were investigated by their proton conductivity, water uptake and dispersion of the catalyst. The results showed that compared with the N212 membrane, the highest water uptake of the composite membrane was significantly improved for about 60% (from 28 wt.% to 44.8 wt.%). It was also found that the proton conductivity of all the composite membranes were higher than that of RN. In addition, the performances of the PEMFC with the self-humidifying composite membranes were also tested on a home-made fuel cell system with H2/O2 gases. The performance of the PEMFC with the best composite membrane was 72% and 4.9 times higher than that with N212 membrane under voltage of 0.4V with TH2/Tcell/TO2 = 80/50/65℃ humidified condition and Tcell = 50℃ dry condition, respectively.