Clues for the Molecular-Level Understanding of Electrocatalysis on Single-Crystal Platinum Surfaces Modified by p-Block Adatoms - Fuel Cell Catalysis: A Surface Science Approach - page 207

& CHAPTER 7
Clues for the Molecular-Level
Understanding of Electrocatalysis on
Single-Crystal Platinum Surfaces
Modified by p-Block Adatoms
V. CLIMENT, N. GARC ´ A-ARA ´ EZ, and J.M. FELIU
Instituto de Electroqu´mica, Universidad de Alicante, Ap. 99, E-03080 Alicante, Spain
7.1 INTRODUCTION
The development of new electrocatalytic materials by deposition of foreign adatoms
on a host metal is currently a very active area of research in surface electrochemistry.
It has been demonstrated that the simple modification of the surface composition of
noble metal electrodes constitutes a convenient approach to enhance their electrocata-
lytic properties in a controlled way, as an alternative to the formation of bulk surface
alloys. The deposition of submonolayer amounts of foreign metal adatoms can
enhance the electrocatalytic activity of a given electrode or improve its selectivity.
The localized modification of the surface composition offers several advantages,
especially for the investigation from a fundamental point of view of the mechanism
of electrocatalytic enhancement. It should be kept in mind that the electrocatalytic
activity produced by submonolayer modification will not be stable in long-term prac-
tical applications, unless periodic regeneration of the adlayers is performed. Still, this
approach will be useful to understand the reactivity of alloys and intermetallic com-
pounds in an easy and controllable way. Normally, a given electrode can be modified
with several surface ad-species, allowing easy systematic study of a broad range of
compositions. This approach is especially advantageous when the initial electrode
substrate can be recovered by removing the surface modifier, and, thus, a new electrode
can be easily prepared with a different surface composition, a requisite that cannot be
accomplished with bulk alloys. Also, from a fundamental point of view, this method-
ology allows one to perform studies with proper control of the surface structure, a