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Investigation of the Phase transformation in FePtM nanoparticles (M= Ag, Cu) at atomic scale for optimized oxygen reduction catalysis.

Abstract : 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. In FePtAg, the phase transition to ordered structure was shown to be induced by Ag doping; a high coercivity of 5.23 kOe and ultrafine size FePtAg nanoparticles (3.5 ± 0.5 nm) has been achieved. 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%. Finally, a mass activity of 11.7 times larger than Pt/C was achieved for optimized FePtCu nanoparticles, with core‒shell Cu/FePt structure and truncated‒octahedron shape.
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  • HAL Id : tel-02469343, version 1

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Xu Chen. Investigation of the Phase transformation in FePtM nanoparticles (M= Ag, Cu) at atomic scale for optimized oxygen reduction catalysis.. Physics [physics]. Normandie Université; Université de Wuhan (Chine), 2019. English. ⟨NNT : 2019NORMC235⟩. ⟨tel-02469343⟩

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