Synthesis of L10-Iron Triad (Fe, Co, Ni)/Pt Intermetallic Electrocatalysts via a Phosphide-Induced Structural Phase Transition

Structurally ordered L1(0)-iron triad (Fe, Co, Ni)/Pt with a M(iron triad)/Pt ratio asymptotic to 1:1 has drawn increasing attention in oxygen reduction reaction (ORR) electrocatalysis and fuel cell technologies by virtue of the high performance derived from their strong surface strain. However, the synthesis of intermetallic L1(0)-M(iron triad)Pt generally requires the accurate content control of the multicomponent and the sufficient thermal energy to overcome the kinetic barrier for atom diffusion. This work reports a synthesis of sub asymptotic to 5 nm L1(0)-intermetallic nanoparticles using phosphide intermediate-induced structural phase transition. Taking the L1(0)-CoPt intermetallic, for example, the formation of the L1(0) structure depends on the Co2P intermediates can provide abundant P vacancies to accelerate the Pt diffusion into the orthorhombic Co-rich skeletons, instead of the traditional route of intermetallic from solid solution. L1(0)-CoPt prepared by this method has a high degree of ordering and shows the broad adaptability of various Pt-based electrocatalysts with different loading and states to improve their electrocatalytic performance. Additionally, the other L1(0)-M(iron triad)Pt intermetallics, i.e., L1(0)-NiPt and L1(0)-FePt, are also prepared through this phosphide-induced phase transition. The findings provide a promising strategy for designing other intermetallic materials alloy materials using a structural phase transition induced by a second phase.

Automated summary

This study successfully synthesized sub-asymptotic to 5 nm L1(0)-intermetallic nanoparticles using phosphide intermediate-induced structural phase transition. The formation of L1(0) structure, exemplified by L1(0)-CoPt, depended on Co2P intermediates that provided abundant phosphorus vacancies to accelerate platinum diffusion into the orthorhombic cobalt-rich skeletons. L1(0)-CoPt prepared by this method showed a high degree of ordering and demonstrated broad adaptability of various Pt-based electrocatalysts to improve their electrocatalytic performance. Moreover, other L1(0)-M(iron triad)Pt intermetallics, namely L1(0)-NiPt and L1(0)-FePt, were also successfully prepared through this phosphide-induced phase transition.