The Effect of Structurally Well-Defined Pt Modification on the Electrochemical and Electrocatalytic Properties of Ru(0001) Electrodes - Fuel Cell Catalysis: A Surface Science Approach - page 464

kinetically hindered by strongly bound, coadsorbed H ad (H upd ). At sufficiently high
potentials, however, H upd can be removed oxidatively as H þ , which allows also
higher OH ad and O ad coverages to be formed.
Electrochemical Properties Typical cyclic voltammograms (CVs) of Ru(0001) in
an HClO 4 electrolyte are shown in Fig. 14.2. The figure also includes information on
(i) the ex situ low energy electron diffraction/reflection high energy electron diffrac-
tion (LEED/RHEED) patterns reported for emersion at three different potentials by
Zei and Ertl [Zei and Ertl, 2000] and (ii) the anodic charges, relative to a surface
free of adsorbed species that were determined by cyclic voltammetry in combination
with CO displacement experiments by El-Aziz and Kibler [El-Aziz and Kibler, 2002].
A positive charge (H upd displacement) was only observed when CO was offered at
E , 0.1 V, indicating that only under these conditions is the adlayer dominated by
Figure 14.2 Cyclic base voltammograms of Ru(0001) in 0.1 M HClO 4 ,50mVs 21 :
scan range 0.1 - 1.05 V (solid line) and 20.1221.05 V (dotted line). Also indicated are
LEED patterns reported in [Zei and Ertl, 2000] after emersion at 0.35, 0.75, and 1.2 V and
anodic charges per surface atom transferred at different potentials according to El-Aziz and
Kibler [2002].