Microwave assisted polyol method for the preparation of Pt/C, Ru/C and PtRu/C nanoparticles and its application in electrooxidation of methanol
Résumé
A polyol process activated by microwave irradiation was implemented to prepare efficient Pt/C, Ru/C and Pt1Ru1/C electrocatalysts for methanol oxidation with reducing synthesis cost and time. Study of the post-synthesis mixture by UV-visible spectroscopy led to determine the minimum batch temperature and synthesis time necessary for the complete reduction of metal salts. It was shown that disappearance of metal salts and colloid formation took place after 5 min at 100 degrees C for Pt, 5 min at 130 degrees C for Ru and 5 min at 160 degrees C for Pt1Ru1. The PtRu catalyst characterizations by TGA, TEM and XRD indicated that the nominal loading and nominal composition were achieved, and that the structure of this material consisted of a mixture of Pt0.8Ru0.2 monocrystalline particles of ca. 2.5-3.0 nm, RuO2 nanoclusters and probably Ru nanoclusters. Pt1Ru1/C catalyst displayed a high activity towards CO and methanol electrooxidation, with onset potentials of ca. 0.2 V lower than those obtained on Pt/C catalysts, and a low surface poisoning at 0.6 V vs. as demonstrated by chronoamperometry measurement RHE and in situ infrared reflectance spectroscopy.