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, Cu) à l'échelle atomique pour la catalyse optimisée de la réduction de l'oxygène, Etude de la transformation de phase dans les nanoparticules FePtM n(M= Ag

, Ce travail a étudié des nanoparticules FePtAg et FePtCu ordonnées issues de la synthèse « one-pot ». Pour FePtAg, nous avons démontré que la transformation vers la structure ordonnée était induite par le dopage Ag; une coercivité de 5.23 kOe et des nanoparticules de FePtAg de taille ultrafine (3.5 ± 0.5 nm) ont été obtenues. Pour les nanoparticules FePtCu, l'effet d'alliage de Cu s'est avéré constituer la force motrice pour la mise en ordre. En comparaison avec le Pt/C de référence, Les piles à combustible à membrane échangeuse de protons sont prometteuses en tant que nouveaux dispositifs de conversion d'énergie en raison de leur rendement élevé et de leur faible impact sur l'environnement

. Mots-clés:-fept and F. Feptag, Microscopie électronique à transmission, Oxydo réduction, Electrocatalyse, Magnétisme, Mise en ordre Investigation of the Phase transformation in FePtM nanoparticles (M= Ag, Cu) at atomic scale for optimized oxygen reduction catalysis

, Proton exchange membrane fuel cells are promising as novel energy conversion devices due to their high efficiency and low environmental impact. However, the platinum loadings needed for compensating the poor kinetics in the oxygen reduction reaction hinder their widespread applications in new energy vehicles and stations. Recently, it has become possible to enhance the catalysts activity based on geometrical and/or electronic effects. In this vein, Pt?based binary alloys with ordered structure have demonstrated enhanced activity and durability, while, contributing to decrease the weight of Pt. In this work, we have investigated ordered FePtAg and FePtCu nanoparticles from one-pot synthesis, with the objective to develop high performance catalysts by improving their activity and durability

, For the FePtCu nanoparticles, the Cu alloying effect was found to constitute the driving force for ordering. As related to benchmark Pt/C, our optimized core-shell structured Cu/FePtCu nanoparticles exhibited a mass activity 4 times higher with only 3 % durability attenuation in contrast to 34.2% for Pt/C catalyst. Finally, a mass activity of 11.7 times larger than Pt/C was achieved for optimized FePtCu nanoparticles, 23 kOe and ultrafine size FePtAg nanoparticles (3.5 ± 0.5 nm) has been achieved