TY - JOUR

T1 - Compatibility of field emitter studies of oscillating surface reactions with single crystal measurements

T2 - Catalytic CO oxidation on Pt

AU - Suchorski, Yu

AU - Imbihl, R.

AU - Medvedev, V. K.

N1 - Funding Information: Financial support from the Deutsche Forschungsgemeinschaft is gratefully acknowledged. One of the authors (V.K.M.) was supported by INTAS-Ukraine Program (project 95-0186).

PY - 1998/4/10

Y1 - 1998/4/10

N2 - Kinetic oscillations in catalytic CO oxidation on Pt have been studied on large (millimeter size) single crystal planes of Pt as well as on a Pt field emitter tip that exposes different crystal facets of nanometer size. In order to examine the compatibility of results from the two types of experiments, the regions of different dynamical behavior (bifurcation diagram) have been mapped out in pco, T-parameter space using a field electron microscope (FEM) and a field ion microscope (FIM). The comparison with the results of single crystal measurements shows that in the case of applied electrostatic fields less than 5 V nm-1 (FEM), the field-induced effects are negligible, but they are significant for fields exceeding 12 V nm-1 (FIM). The field-induced shift of the bifurcation diagram toward lower pco values, observed with FIM, is explained in terms of a field-modified interaction of CO and O2 with Pt studied here with field ion appearance energy spectroscopy. With coadsorbed lithium (submonolayer coverage), the existence range for rate oscillations is shifted toward higher pco values. This shift is attributed to a redistribution of the electron density at the surface induced by alkali metal co-adsorption.

AB - Kinetic oscillations in catalytic CO oxidation on Pt have been studied on large (millimeter size) single crystal planes of Pt as well as on a Pt field emitter tip that exposes different crystal facets of nanometer size. In order to examine the compatibility of results from the two types of experiments, the regions of different dynamical behavior (bifurcation diagram) have been mapped out in pco, T-parameter space using a field electron microscope (FEM) and a field ion microscope (FIM). The comparison with the results of single crystal measurements shows that in the case of applied electrostatic fields less than 5 V nm-1 (FEM), the field-induced effects are negligible, but they are significant for fields exceeding 12 V nm-1 (FIM). The field-induced shift of the bifurcation diagram toward lower pco values, observed with FIM, is explained in terms of a field-modified interaction of CO and O2 with Pt studied here with field ion appearance energy spectroscopy. With coadsorbed lithium (submonolayer coverage), the existence range for rate oscillations is shifted toward higher pco values. This shift is attributed to a redistribution of the electron density at the surface induced by alkali metal co-adsorption.

KW - Alkali metals

KW - Carbon monoxide

KW - Catalysis

KW - Field emission

KW - Field emission microscopy

KW - Field ion microscopy

KW - Oxygen

KW - Platinum

KW - Surface chemical reaction

UR - http://www.scopus.com/inward/record.url?scp=0032051034&partnerID=8YFLogxK

U2 - 10.1016/S0039-6028(98)00043-0

DO - 10.1016/S0039-6028(98)00043-0

M3 - Article

AN - SCOPUS:0032051034

VL - 401

SP - 392

EP - 399

JO - Surface science

JF - Surface science

SN - 0039-6028

IS - 3

ER -