Study On The Preparation And Performance Of PT/PD-based Catalysts For Alkaline Fuel Cells

Alkaline fuel cell has attracted much attention in overseas and domestic researchfield due to its efficient, green and safe advantages. Through the efforts of manyresearchers, great progress has been made in the research and development of alkalinefuel cell. However, catalytic activity and durability of electrocatalyst still need to beimproved. Based on the two aspects, the degradation mechanism of Pt/C catalyst inalkaline medium has been systematically studied. PdAg nanowires have been fabricatedand their catalytic activity and durability have been investigated.20wt%Pt/C catalyst was prepared by microwave-assisted glycol reduction methodand its stability in acidic and alkaline medium was investigated by cyclic voltammetryscanning method. The result indicates that the EASA degradation is much more obviousin alkaline medium, indicating that Pt/C catalyst is less stable in alkaline medium thanin acidic medium. The constant potential oxidation and potentiodynamic oxidation testsin alkaline medium show that the corrosion of carbon support is much more severe at0.3V than at-0.3V and0V, and its corrosion is not the main reason of the performanceattenuation of Pt/C catalyst. The potential cycling test with different potential rangepresents that EASA degradation in the potential range from-0.3V to0.3V is mostprominent, indicating that the dissolution-redeposition process of Pt particles is themain reason attributed to performance attenuation of Pt/C catalyst in alkaline medium.The Ag nanowires with the diameter and length of70nm and5μm have beensynthesized via ethylene glycol reducing method. By using the Ag nanowires as thetemplates, PdAg nanowires were fabricated through the replacement reaction betweenthe Ag nanowires and palladium nitrate, and the factors including the concentration ofpalladium nitrate, the addition quantity of palladium nitrate and the reaction temperaturethat influencing the catalytic properties was also investigated. The results display thatthe catalytic activity and stability of PdAg NWs are better than that of Pd/C catalysttoward both the methanol and ethanol electrooxidation reaction in alkaline medium. TheCO stripping experiment shows that PdAg NWs catalyst has stronger resistance toCO-poisoning than Pd/C catalyst, which is beneficial to desorption of CO on theelectrode surface. LSV test results indicate that the oxygen reduction reaction on PdAgNWs catalyst in alkaline medium mainly undergoes four-electronic pathway.