Unexpected behavior of the surface composition of PtRh alloys during chemical reaction.
The changes in the surface composition of a Pt(50)Rh(50)(100) alloy due to an ongoing 2H(2) + O(2)-->2H(2)O chemical reaction have been studied in situ. Exploiting the high-energy resolution and surface sensitivity of synchrotron radiation core-level spectroscopy it was possible to monitor the population of the two transitions metals atoms at the gas-surface interface. Sequences of fast high-resolution core-level spectra of the Rh3d(5/2), Pt4f(7/2), and O1s core levels showed a continuous exchange of atoms between the first and subsurface layers. An unexpected Pt surface enrichement was found under slightly oxidizing conditions, opposite to what found in a highly oxidizing atmosphere.
Baraldi
Alessandro
A
Dipartimento di Fisica, Università di Trieste, Via Valerio 2, 34127 Trieste, Italy. alessandro.baraldi@elettra.trieste.it
Giacomello
Dario
D
Rumiz
Luca
L
Moretuzzo
Mauro
M
Lizzit
Silvano
S
Buatier de Mongeot
Francesco
F
Paolucci
Giorgio
G
Comelli
Giovanni
G
Rosei
Renzo
R
Nieuwenhuys
Bernard E
BE
Valbusa
Ugo
U
Kiskinova
Maya P
MP