High Performance Direct Methanol Fuel Cell Catalysts

• Main Authors: Huang-Yu Lee, 李皇諭
• Other Authors: Peter Po-Jen Chu
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/83528877736594153250

博士 === 國立中央大學 === 化學研究所 === 100 === Direct methanol fuel cells (DMFC) shows potential as a new energy source due to its relatively high energy density, easy to store, transport, and reload. However, the low catalyst efficiency, insufficient durability and high manufacture cost are hurdles for immediate commercialization. The first aim of the research covered in this thesis was to improve the catalytic activity and to extend catalyst durability by using polyaniline (PANi) coated on both carbon nanotube (CNT) and ground active carbon (ACg) surface to form PCNT and PACg nanocomposites, and later we examine the different effects of polyaniline, polypyrrole, and polythiophene coating on Vulcan XC-72 to form P1X, Ppy1X and Pth1X nanocomposites as the anode catalysts supports for direct methanol fuel cell. A second part of the study was to examine a novel cathode catalyst, PtPb alloy, which exhibited high activity and tolerance corrosion in acid media. All the anode electrocatalysts were prepared by depositing Pt-Ru alloy nanoparticles on nanocomposites surface through borohydride reduction. The alloying Pt-Pb nanoparticles were supported on ACg and P1CNT by a mild reduction procedure under temperatures below 200oC. Using polyaniline coating on Vulcan XC-72 as the support to form anode catalyst yielded methanol oxidation catalytic activity higher than polypyrrole and polythiophene nanocomposites catalysts. In comparison, the polyaniline coating on different the type carbon supports, the PtRuP1CNT showed highest methanol oxidation performance due to P1CNT formed 3D porous framework catalyst layer, afforded more active sites and easier transport of methanol and CO2. The platinum-lead alloys tended to follow mainly a 4-electron mechanism, which implied reduced H2O2 formation and first order with respect to the dissolved oxygen. PtPbACg catalyst showed high stability including low ECSA change ratio and carbon corrosion under consecutive scan in 0.1 M HClO4. In summary, present study demonstrated that the PANi coating prevented aggregation, loss of Pt particles, and thereby improved long-term stability of fuel cell catalysts on both anode and cathode. It also unveiled a new design of more durable catalysts by coating conducting polymer layer on carbon support which improved catalytic activity, CO tolerance and stability over other catalysts based on the current method technique. PtPb binary alloy nanoparticles could be used as a new potential cathode catalyst metal for both PEMFC and DMFC