Local heterojunctions of atomic Pt clusters boost the oxygen reduction activity of Rucore@Pdshell nanocrystallites

Ru-Pd nanoparticles (NPs) with Pt atomic cluster modification were synthesized using polyol reactions with a sequence design. Such modification resulted in the formation of Ru in the inner core and Pd on the outer shell structure (Rucore-Pdshell) via transmetalation between the Pt ion and Pd atom followed by thermal reduction. The Pt modified Rucore-Pdshell NPs improve the on-set potential by 0.041 volt and reduce Pt loading to less than ∼2%, as compared with that of carbon supported Pt NPs. For the optimum case, the MA (current degradation) of Ru-Pd NPs is improved (suppressed) by ∼345% (18.1%) in the accelerated degradation test (ADT) at 0.85 volt (vs. RHE) for 5000 cycles by intercalating Pt clusters (2 to 9 at%) in the NP surface. These improvements are attributed to the electron localization and reinforcement by surface Pt clusters, which facilitated the oxygen reduction activity and chemical durability of NPs.