A Study on Cathode Catalysts Synthesized with Polyaniline for Proton Exchange Membrane Fuel Cell

• Main Authors: Yu-WenChen, 陳郁文
• Other Authors: Ming-Chang Yang
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/nnkj7a

碩士 === 國立成功大學 === 化學工程學系碩博士班 === 101 === Currently, developement in PEMFC focus on cost reduction and durability improvement of cathode catalysts. One of the methods in reducing the catalysts cost is developing catalysts without precious metal. In this study, the electrochemical activity and other catalyst properties are explored. Furthermore, the relations between mass activity and catalyst properties were established. In this study, polyaniline was pyrolyzed to provide nitrogen active sites for oxygen reduction. The effects of pyrolysis temperature, pyrolysis time at 900 oC, and post-treatment (including acid-treatment and heat-treatment) conditions on electrochemical activity and catalyst properties were explored. Phosphoric acid (PA) precursor and sodium dodecyl sulfate (SDS) precursor were added during aniline polymerization to increase the catalyst activity. The ratio of the precursors to polyaniline were investigated. Furthermore, the relation between mass activity at 0.7 V (vs. Ag/AgCl) and other catalyst properties are summarized. The experiment results show that surface nitrogen content decreased while pyrolysis temperature increased. The pyrolysis temperature affected activity significantly, and the optimal temperature was 900 oC. The catalysts with pyrolysis time of 900 oC for 1 hour showed the highest activity which is 4.4 times of the as-prepared catalyst. The activity of catalysts after acid-treatment was 1.6 times of that of catalysts after pyrolysis. The activity of catalysts after heat-treatment was 1.5 times of that of catalysts after acid-treatment. Experiment results showed that addition of PA precursors gave a broken structure with large edge plane exposure and the surface nitrogen content was twice of that of the catalysts without PA addition. The catalysts activity with PA: ANI = 2: 9 after post-treatment were 1.6 times of that with PA: ANI = 0: 9. The addition of SDS resulted in higher surface nitrogen content. The contact angle of catalyst increased with the amout of SDS. The catalysts added with SDS: ANI = 2.25: 9 after post-treatment had higher activity, which were 1.9 times of that of SDS: ANI = 0: 9. Catalysts activity with SDS: PA: ANI = 1.35: 3: 9 after post-treatment were 2.4 times of that with SDS: PA: ANI = 0: 0: 9. In the single cell results, the maximum power density (25.9 mW/cm2) of best home-made catalyst was 24% of that of commercial Pt/C catalyst. According to experiment results, the sum of pyridinic N and quaternary N and the integration area below CV curve increased with catalysts activity.