TY - JOUR

T1 - Self-induced long-range surface strain improves oxygen reduction reaction

AU - Ozório, Mailde S.

AU - Nygaard, Marcus F.

AU - Petersen, Amanda S.

AU - Behm, R. Jürgen

AU - Rossmeisl, Jan

N1 - Funding Information: The authors acknowledge support from the Danish National Research Foundation Center for High-Entropy Alloy Catalysis (CHEAC) DNRF-149. Publisher Copyright: © 2024

PY - 2024

Y1 - 2024

N2 - For decades, it has been recognized that alloying platinum (Pt) with a secondary metal can enhance the catalytic activity of the oxygen reduction reaction (ORR) compared to pristine Pt catalysts. However, the mechanisms underlying this phenomenon vary significantly from one alloy to another. Here, we report the results of a computational study on the origin of the experimentally observed enhanced ORR activity of AgxPt1-x/Pt(1 1 1) monolayer surface alloy with 7 %–50 % Ag contents. A phase-separation model was developed and able to generate 2D phase-separation distributions of Ag and Pt atoms in AgxPt1-x/Pt(1 1 1) surfaces in line with atomic resolution scanning tunneling microscopy. We employed DFT-calculated *OH adsorption energy as a descriptor to obtain the activity of those surfaces, which reveals the ORR activity dominated by the reaction on Pt(Pt6) heptamers and also gives evidence of long-range self-induced surface strain as the source of the enhanced activity of binary AgxPt1-x/Pt(1 1 1) surfaces, i.e., the slightly larger surface Ag atoms induce a compressive strain of Pt-Pt bonds of the Pt(Pt6) heptamers, which increases the activity of binary surfaces compared to the pristine Pt(1 1 1) surface. Moreover, the excellent simulated-experimental agreement for the polarization curves shows the high quality of this approach and its more general potential for an improved understanding of the catalytic properties of inhomogeneous binary surfaces as the basis for a rational design of binary catalysts.

AB - For decades, it has been recognized that alloying platinum (Pt) with a secondary metal can enhance the catalytic activity of the oxygen reduction reaction (ORR) compared to pristine Pt catalysts. However, the mechanisms underlying this phenomenon vary significantly from one alloy to another. Here, we report the results of a computational study on the origin of the experimentally observed enhanced ORR activity of AgxPt1-x/Pt(1 1 1) monolayer surface alloy with 7 %–50 % Ag contents. A phase-separation model was developed and able to generate 2D phase-separation distributions of Ag and Pt atoms in AgxPt1-x/Pt(1 1 1) surfaces in line with atomic resolution scanning tunneling microscopy. We employed DFT-calculated *OH adsorption energy as a descriptor to obtain the activity of those surfaces, which reveals the ORR activity dominated by the reaction on Pt(Pt6) heptamers and also gives evidence of long-range self-induced surface strain as the source of the enhanced activity of binary AgxPt1-x/Pt(1 1 1) surfaces, i.e., the slightly larger surface Ag atoms induce a compressive strain of Pt-Pt bonds of the Pt(Pt6) heptamers, which increases the activity of binary surfaces compared to the pristine Pt(1 1 1) surface. Moreover, the excellent simulated-experimental agreement for the polarization curves shows the high quality of this approach and its more general potential for an improved understanding of the catalytic properties of inhomogeneous binary surfaces as the basis for a rational design of binary catalysts.

KW - Bimetallic catalysts

KW - Inhomogeneous surfaces

KW - Modelling

KW - Oxygen reduction reaction

KW - PtAg

KW - Strain effects

U2 - 10.1016/j.jcat.2024.115484

DO - 10.1016/j.jcat.2024.115484

M3 - Journal article

AN - SCOPUS:85190284264

VL - 433

JO - Journal of Catalysis

JF - Journal of Catalysis

SN - 0021-9517

M1 - 115484

ER -