As environmental concerns and the transition to a carbon-neutral society gain importance, proton exchange membrane fuel cells (PEMFCs) using hydrogen as a fuel have attracted significant attention as eco-friendly energy technology. Although Pt is the primary catalyst for PEMFC anodes, its high cost and limited availability pose major barriers to commercialization. To address these challenges, non-Pt catalysts, alloy catalysts, and core-shell structured catalysts have been extensively studied; nevertheless, performance degradation and structural instability remain significant issues. In this study, we design Pt-lean Pt1Co4 alloy nanoparticles encapsulated with an ultrathin carbon shell derived from the carbon sources of the metal precursor ligands. Notably, after synthesizing the carbon-incorporated alloy nanoparticles, heat treatment under a carbon monoxide (CO) atmosphere induces selective surface segregation of Pt atoms due to their strong CO binding affinity, occurring before the carbonization temperature is reached for carbon shell formation, resulting in a Pt-enriched surface structure. The carbon shell imparts a nano-confinement effect that effectively suppresses particle growth and aggregation during heat treatment, thereby significantly enhancing electrochemical stability. Remarkably, despite a 55% reduction in Pt content, the combination of surface segregation and near-surface alloying allows the Pt-lean alloy catalyst to maintain hydrogen oxidation reaction activity comparable to a bare Pt catalyst while providing superior durability. Owing to this dual function of heat treatment, the design of the Pt-lean alloy catalyst structure offers a promising strategy for developing highly efficient and cost-effective anode catalysts for PEMFCs.
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2025 The Author(s). Aggregate published by SCUT, AIEI, and John Wiley & Sons Australia, Ltd.
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