The segregation resistance of the Pt2ML/Os/Pd3Al sandwich catalyst for oxygen reduction reaction: a density functional theory studyElectronic supplementary information (ESI) available. See DOI: 10.1039/c6cp05869h

• Main Authors: Xiao, B. B, Jiang, X. B, Yang, X. L, Jiang, Q, Zheng, F
• Format: Article
• Language: English
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/c6cp05869h

Pt 1ML /Pd 3 Al, which comprises a Pd 3 Al core protected by a Pt monolayer, may experience Al dealloying because of the strong affinity of Al toward O. To circumvent this issue, the Pt 2ML /Os/Pd 3 Al catalyst has been designed to suppress the migration of Al by inserting an Os monolayer at the interface between the Pd 3 Al core and two Pt monolayers. On the basis of segregation energies, Al leaching from the core to the 1st layer is determined to be endothermic even under O coverage, indicating an energetic preference for Al to reside in the core structure. The Pt 2ML /Os/Pd 3 Al catalyst benefits from the energetic disadvantage of the inward movement of Os and the presence of the 2 ML Pt layer. As an ORR electrocatalyst, the relatively weak adsorption ability of Pt 2ML /Os/Pd 3 Al suggests improved ORR activity. Finally, a representative OOH association mechanism with low reaction barriers of 0.46, 0.31, 0.38 and 0.41 eV for the OOH formation, OOH dissociation, OH formation and H 2 O formation steps suggests that the catalyst can effectively activate the O-O bond and eliminate OH, which can act as a catalytic poison. These findings suggest the design of stable sandwich catalysts as potential candidates for ORR electrocatalysis. The Pt 2ML /Os/Pd 3 Al catalyst is designed to suppress the migration of Al by inserting an Os monolayer at the interface between the Pd 3 Al core and Pt shell.