Pt-surface stabilization by high-entropy alloys for enhancing oxygen reduction reaction property: Single-crystal model catalyst study

• Published in: Electrochemistry communications Vol. 159; p. 107657
• Main Authors: Chida, Yoshihiro, Tomimori, Takeru, Todoroki, Naoto, Wadayama, Toshimasa
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.02.2024; Elsevier
• Subjects: High-entropy alloys; Model catalyst study; Oxygen reduction reaction; Platinum; Surface free energy; Surface segregation; High-entropy alloys; Model catalyst study; Platinum; Surface segregation; Surface free energy; Oxygen reduction reaction
• ISSN: 1388-2481; 1873-1902
• DOI: 10.1016/j.elecom.2023.107657

[Display omitted] •Pt/Cr-Mn-Co-Ni(111) surface showed excellent ORR activity and durability.•Pt/Cr-Co-Ni(111) surface showed drastic deactivation by potential cycle loadings.•Surface microstructure, notably Cr's distribution, largely affects ORR properties.•Thermodynamical stability of HEAs determines the surface elemental distributions. In this work, we study the oxygen reduction reaction (ORR) properties of Pt-containing 3d transition-metal high-entropy alloy (Pt-HEA) surfaces, focusing on the constituent alloying elements. The surface Pt and underlying Cr-Mn-Co-Ni(111) (Pt/Cr-Mn-Co-Ni(111)) stacked lattice layers, which are synthesized through the vacuum deposition of the underlying alloy and surface Pt stacking layers on Pt(111) substrate, exhibit high pristine ORR activity and structural stability under potential-cycle loading, compared to Pt/Cr-Co-Ni, Pt/Mn-Co-Ni, and Pt/Co-Ni(111) surfaces. The outperformed ORR properties are attributed to the effective suppression of the surface segregation of Cr. This study demonstrates that not only the “high-entropy” effect induced by increasing the numbers of constituent elements but also the “chemical affinity” of Pt and the individual HEA constituent elements determine the ORR performances of Pt-HEA.