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

Abstract Structurally ordered L1₀‐iron triad (Fe, Co, Ni)/Pt with a M(iron triad)/Pt ratio ≈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 L1₀‐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 ≈5 nm L1₀‐intermetallic nanoparticles using phosphide intermediate‐induced structural phase transition. Taking the L1₀‐CoPt intermetallic, for example, the formation of the L1₀ 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. L1₀‐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 L1₀‐M(iron triad)Pt intermetallics, i.e., L1₀‐NiPt and L1₀‐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.