Electronic and structural study of Pt-modified Au vicinal surfaces: a model system for Pt-Au catalysts

Autor(es)

Prieto, Mauricio J. ^[1] ; Carbonio, Emilia A. ^[1] ; Fatayer, Shadi ^[1] ; Landers, Richard ^[1] ; de Siervo, Abner ^[1]

Afiliação do(s) autor(es)

^[1] Univ Estadual Campinas, Inst Fis Gleb Wataghin, Dept Fis Aplicada, BR-13083859 Campinas, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Physical Chemistry Chemical Physics; v. 16, n. 26, p. 13329-13339, 2014.
• Citações Web of Science: 9

Resumo

Two single crystalline surfaces of Au vicinal to the (111) plane were modified with Pt and studied using scanning tunneling microscopy (STM) and X-ray photoemission spectroscopy (XPS) in ultra-high vacuum environment. The vicinal surfaces studied are Au(332) and Au(887) and different Pt coverage (yPt) were deposited on each surface. From STM images we determine that Pt deposits on both surfaces as nanoislands with heights ranging from 1 ML to 3 ML depending on yPt. On both surfaces the early growth of Pt ad-islands occurs at the lower part of the step edge, with Pt ad-atoms being incorporated into the steps in some cases. XPS results indicate that partial alloying of Pt occurs at the interface at room temperature and at all coverage, as suggested by the negative chemical shift of Pt 4f core line, indicating an upward shift of the d-band center of the alloyed Pt. Also, the existence of a segregated Pt phase especially at higher coverage is detected by XPS. Sample annealing indicates that the temperature rise promotes a further incorporation of Pt atoms into the Au substrate as supported by STM and XPS results. Additionally, the catalytic activity of different PtAu systems reported in the literature for some electrochemical reactions is discussed considering our findings. (AU)

• Processo FAPESP: 12/16860-6 - Estudo da estrutura eletrônica e atômica de nanofitas de tetrafenil porfirinas auto-ordenadas em superfícies vicinais
• Beneficiário: Shadi Passam Fatayer
• Modalidade de apoio: Bolsas no Brasil - Mestrado
• Processo FAPESP: 07/54829-5 - Estrutura eletrônica e geométrica de nano materiais: um estudo por radiação sincroton
• Beneficiário: Richard Landers
• Modalidade de apoio: Auxílio à Pesquisa - Temático