TY - JOUR
T1 - Pt promotion and spill-over processes during deposition and desorption of upd-Had and OHad on PtxRu1-x/Ru(0001) surface alloys
AU - Hoster, Harry E.
AU - Janik, Michael J.
AU - Neurock, Matthew
AU - Behm, R. Jürgen
PY - 2010
Y1 - 2010
N2 - The electrochemical adsorption of underpotential deposited hydrogen (upd-Had) and OHad on structurally well-defined PtxRu1-x/Ru(0001) surface alloys was investigated by cyclic voltammetry and density functional theory (DFT) calculations. The adsorption energies of both upd-Had and OHad decrease with increasing Pt content in the adsorption ensemble, shifting the onset of upd-Had and OHad formation to increasingly cathodic and anodic potentials, respectively. For bare Ru(0001) and for Ru3 sites in the surface alloy, the stability regions of these two species overlap or almost overlap, respectively. Similar to previous findings for upd-Had adsorption/desorption on partly Pt monolayer island covered Ru(0001) surfaces (J. Phys. Chem. B 2004, 108, 14780), we find a sharp peak at ∼100 mV vs. RHE in each scan direction, which is attributed to a Pt catalyzed OHad↔ upd-Had replacement on Ru3 sites, via adsorption on Pt rich sites and spill-over to Ru3 sites. The decrease of the integrated charge in these peaks with the third power of the Ru surface concentration, which for a random distribution of surface atoms reflects the availability of Ru3 sites, supports the above assignment.
AB - The electrochemical adsorption of underpotential deposited hydrogen (upd-Had) and OHad on structurally well-defined PtxRu1-x/Ru(0001) surface alloys was investigated by cyclic voltammetry and density functional theory (DFT) calculations. The adsorption energies of both upd-Had and OHad decrease with increasing Pt content in the adsorption ensemble, shifting the onset of upd-Had and OHad formation to increasingly cathodic and anodic potentials, respectively. For bare Ru(0001) and for Ru3 sites in the surface alloy, the stability regions of these two species overlap or almost overlap, respectively. Similar to previous findings for upd-Had adsorption/desorption on partly Pt monolayer island covered Ru(0001) surfaces (J. Phys. Chem. B 2004, 108, 14780), we find a sharp peak at ∼100 mV vs. RHE in each scan direction, which is attributed to a Pt catalyzed OHad↔ upd-Had replacement on Ru3 sites, via adsorption on Pt rich sites and spill-over to Ru3 sites. The decrease of the integrated charge in these peaks with the third power of the Ru surface concentration, which for a random distribution of surface atoms reflects the availability of Ru3 sites, supports the above assignment.
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U2 - 10.1039/c003635h
DO - 10.1039/c003635h
M3 - Article
C2 - 20596565
AN - SCOPUS:77957990187
SN - 1463-9076
VL - 12
SP - 10388
EP - 10397
JO - Physical Chemistry Chemical Physics
JF - Physical Chemistry Chemical Physics
IS - 35
ER -