Shape-Controlled Synthesis of Dumbbell-like Pt–Fe(3)O(4)–MnO(x) Nanoparticles by Governing the Reaction Kinetics

[Image: see text] The production of shape-controlled heterometallic nanoparticles (NPs) consisting of Pt and nonprecious metal oxides is crucial to demonstrate the composition–property relationship of NPs. Herein, we report a facile one-pot approach for the controlled synthesis of dumbbell-like Pt–Fe(3)O(4)–MnO(x) and dendritic Pt–MnO(x) 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–MnO(x) NPs were synthesized through the assembly of small seed NPs. On the other hand, dumbbell-like Pt–Fe(3)O(4)–MnO(x) 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–Fe(3)O(4)–MnO(x) 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.