Theory Guided Fine-Tune of Strain Effects in Pt Ternary Alloy via Rare Earth Templating: Achieving High Performance PEMFCs Catalysts.

Abstract

The sluggish kinetics and insufficient durability of platinum-based catalysts remain crucial barriers limiting proton-exchange-membrane fuel cells (PEMFCs) deployment. Here, we report a theory-guided synthesis combined with rare-earth templating to realize a previously inaccessible Pt₅Co-like phase with tailored atomic-scale strain. Guided by density functional theory (DFT) calculations, we identified that a Pt₅Co-like sublayer can induce a unique mild compressive strain (-1.24%) to the Pt(111) shell and an optimal *OH binding energy shift (ΔE ≈ 0.11 eV). This shift positions the alloy catalyst near the apex of the oxygen reduction reaction activity volcano. This prediction guided the synthesis of ternary alloy Pt₅(Ce)Co@Pt multilayer nanoparticles, featuring a Ce-stabilized core, a Pt₅Co-like sublayer, and a Pt-rich shell. This catalyst demonstrates both exceptionally high activity and durability, achieving a mass activity of 2.6 A∙mg_Pt ^-1 in rotating disk electrode testing. In fuel cell membrane electrode assembly tests, Pt₅(Ce)Co@Pt achieves a current density of 1.9 A∙cm^-2 at 0.7 V under heavy-duty vehicle conditions. Remarkably, it maintains 1.2 A∙cm^-2 after 1 80 000 AST cycles, doubling the U.S. DOE 2025 target. This work demonstrates a rational design strategy that DFT-guided strain engineering integrates with rare-earth templating to advance Pt-based catalysts for fuel cell applications.