| Cathode catalyst is one of the main factors impeding commercialization of proton exchange membrane fuel cells (PENFCs) because of the slow kinetics of oxygen reduction reaction (ORR), high cost of the noble catalyst and its low utilization. PPy-based transitional metal catalyst demonstrates excellent catalytic activity and durability for oxygen reduction with the special structure and characteristics, and is regarded as a kind of promising cathode catalyst for PEMFCs, much attention has been paid to it in recent years.PPy modified carbon (PPy/C) has been prepared by in-situ polymerization, in this thesis, and analyzed with IR, Raman, SEM, and then used as support to synthesize catalyst Co-PPy/C by pyrolysis together with cobalt salt. The effects of heat-treatment temperature, time and atmosphere on the structure and catalytic performance of Co-PPy/C for ORR have also been comparatively studied and the preparing procedure of Co-PPy/C has been optimized.In order to improve the electro-catalytic performance of Co-PPy/C for ORR, TsOH has been used, in this thesis, as dopant to prepare the catalyst of Co-PPy-TsOH/C whose catalytic activity is greatly improved from that of Co-PPy/C. The performance of PEMFC with Co-PPy-TsOH/C as cathode catalyst is much better than that with Co-PPy/C, the peak power density is more than 200mW/cm2 when the loading of Co in cathode is 0.35mg/cm2 and more than 250mW/cm2 when 1atm back pressure is used onto both sides of the MEA, which is apparently larger than the best reported value in literature for Co-PPy/C based cathode catalyst. The mechanism of performance improvement by TsOH modification has also been analyzed in the present work with in-situ thermal analysis, in-situ high temperature XRD, Raman spectra, elemental analysis and TEM.Effects of TsOH and pyrrole content on the electro-catalytic performance of Co-PPy-TsOH/C have been studied and analyzed with Minitab.
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