title: Communication: Enhanced oxygen reduction reaction and its underlying mechanism in Pd-Ir-Co trimetallic alloys.
abstract: Based on a combined density functional theory and experimental study, we present that the electrochemical activity of Pd3Co alloy catalysts toward oxygen reduction reaction (ORR) can be enhanced by adding a small amount of Ir. While Ir tends to favorably exist in the subsurface layers, the underlying Ir atoms are found to cause a substantial modification in the surface electronic structure. As a consequence, we find that the activation barriers of O/OH hydrogenation reactions are noticeably lowered, which would be mainly responsible for the enhanced ORR activity. Furthermore, our study suggests that the presence of Ir in the near-surface region can suppress Co out-diffusion from the Pd3Co substrate, thereby improving the durability of Pd-Ir-Co catalysts. We also discuss the relative roles played by Ir and Co in enhancing the ORR activity relative to monometallic Pd catalysts.
authors.affiliation: Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, USA.
authors.forename: Hyung Chul
authors.initials: HC
authors.lastname: Ham
authors.forename: Dhivya
authors.initials: D
authors.lastname: Manogaran
authors.forename: Kang Hee
authors.initials: KH
authors.lastname: Lee
authors.forename: Kyungjung
authors.initials: K
authors.lastname: Kwon
authors.forename: Seon-ah
authors.initials: SA
authors.lastname: Jin
authors.forename: Dae Jong
authors.initials: DJ
authors.lastname: You
authors.forename: Chanho
authors.initials: C
authors.lastname: Pak
authors.forename: Gyeong S
authors.initials: GS
authors.lastname: Hwang