Shape-Controlled Synthesis of Dumbbell-like Pt–Fe3O4–MnOx Nanoparticles by Governing the Reaction Kinetics

Abstract

The production of shape-controlled hetero-metallic nanoparticles (NPs) consisting of Pt and nonprecious metal oxides is crucial to demonstrate the composition-property relationship of NPs. Herein, we report a facile onepot approach for the controlled synthesis of dumbbell-like Pt-Fe3O4-MnOx and dendritic Pt-MnOx NPs. The key to the success of this synthesis is in changing the quantity of Fe(CO)(5) additive to control the reaction kinetics. In the absence of Fe(CO)(5), dendritic Pt-MnOx NPs were synthesized through the assembly of small seed NPs. On the other hand, dumbbell-like Pt-Fe3O4-MnOx NPs were obtained in the presence of Fe(CO)(5) through controlling the nucleation and growth of Fe and Mn on the Pt NPs, followed by air oxidation. Compared to a Pt/graphene oxide (GO) catalyst, dumbbell-like Pt-Fe3O4-MnOx NPs on GO showed an enhancement of specific activity toward the oxygen reduction reaction owing to the compressive-strain effect exerted on the Pt lattice.