title: Effect of gold subsurface layer on the surface activity and segregation in Pt/Au/Pt3M (where M = 3d transition metals) alloy catalyst from first-principles.
abstract: The effect of a subsurface hetero layer (thin gold) on the activity and stability of Pt skin surface in Pt3M system (M = 3d transition metals) is investigated using the spin-polarized density functional theory calculation. First, we find that the heterometallic interaction between the Pt skin surface and the gold subsurface in Pt/Au/Pt3M system can significantly modify the electronic structure of the Pt skin surface. In particular, the local density of states projected onto the d states of Pt skin surface near the Fermi level is drastically decreased compared to the Pt/Pt/Pt3M case, leading to the reduction of the oxygen binding strength of the Pt skin surface. This modification is related to the increase of surface charge polarization of outmost Pt skin atoms by the electron transfer from the gold subsurface atoms. Furthermore, a subsurface gold layer is found to cast the energetic barrier to the segregation loss of metal atoms from the bulk (inside) region, which can enhance the durability of Pt3M based catalytic system in oxygen reduction condition at fuel cell devices. This study highlights that a gold subsurface hetero layer can provide an additional mean to tune the surface activity toward oxygen species and in turn the oxygen reduction reaction, where the utilization of geometric strain already reaches its practical limit.
authors.affiliation: Fuel Cell Research Center, Korea Institute of Science and Technology (KIST), 39-1 Hawolgok, Seongbuk-gu, Seoul 136-791, South Korea.
authors.forename: Chang-Eun
authors.initials: CE
authors.lastname: Kim
authors.affiliation: Fuel Cell Research Center, Korea Institute of Science and Technology (KIST), 39-1 Hawolgok, Seongbuk-gu, Seoul 136-791, South Korea.
authors.forename: Dong-Hee
authors.initials: DH
authors.lastname: Lim
authors.affiliation: Fuel Cell Research Center, Korea Institute of Science and Technology (KIST), 39-1 Hawolgok, Seongbuk-gu, Seoul 136-791, South Korea.
authors.forename: Jong Hyun
authors.initials: JH
authors.lastname: Jang
authors.affiliation: Fuel Cell Research Center, Korea Institute of Science and Technology (KIST), 39-1 Hawolgok, Seongbuk-gu, Seoul 136-791, South Korea.
authors.forename: Hyoung Juhn
authors.initials: HJ
authors.lastname: Kim
authors.affiliation: Fuel Cell Research Center, Korea Institute of Science and Technology (KIST), 39-1 Hawolgok, Seongbuk-gu, Seoul 136-791, South Korea.
authors.forename: Sung Pil
authors.initials: SP
authors.lastname: Yoon
authors.affiliation: Fuel Cell Research Center, Korea Institute of Science and Technology (KIST), 39-1 Hawolgok, Seongbuk-gu, Seoul 136-791, South Korea.
authors.forename: Jonghee
authors.initials: J
authors.lastname: Han
authors.affiliation: Fuel Cell Research Center, Korea Institute of Science and Technology (KIST), 39-1 Hawolgok, Seongbuk-gu, Seoul 136-791, South Korea.
authors.forename: Suk Woo
authors.initials: SW
authors.lastname: Nam
authors.affiliation: Fuel Cell Research Center, Korea Institute of Science and Technology (KIST), 39-1 Hawolgok, Seongbuk-gu, Seoul 136-791, South Korea.
authors.forename: Seong-Ahn
authors.initials: SA
authors.lastname: Hong
authors.affiliation: Global E3 Institute and Department of Materials Science and Engineering, Yonsei University, 120-749 Seoul, South Korea.
authors.forename: Aloysius
authors.initials: A
authors.lastname: Soon
authors.affiliation: Fuel Cell Research Center, Korea Institute of Science and Technology (KIST), 39-1 Hawolgok, Seongbuk-gu, Seoul 136-791, South Korea.
authors.forename: Hyung Chul
authors.initials: HC
authors.lastname: Ham