Environmental Engineering Reference
In-Depth Information
&
CHAPTER 15
Size Effects in Electrocatalysis of
Fuel Cell Reactions on Supported
Metal Nanoparticles
FREDERIC MAILLARD
Laboratoire d'Electrochimie et de Physico-chimie des Mat´riaux et des Interfaces, LEPMI
UMR 5631 CNRS/UJF/G-INP, BP75, 38402 Saint Martin d'H`res, France
SERGEY PRONKIN and ELENA R. SAVINOVA*
LMSPC UMR-7515, ECPM, Universit´ de Strasbourg, 67087 Strasbourg, France
15.1 INTRODUCTION
For several decades, fuel cell research and development have grown in line with the
worldwide demand for energy, particularly with global warming concerns and the
consequent requirements to reduce consumption of fossil fuels (petrol, coal, and
gas), which produce greenhouse gases. Recently, considerable effort has been directed
to the development of polymer electrolyte membrane fuel cells (PEMFCs), which are
considered as a promising solution to provide electricity for small stationary, mobile
and portable applications [Carrette et al., 2000]. Various metal-rich electrocatalysts,
usually based on carbon-supported Pt and/or its alloys, are used to accelerate fuel
cell reactions in PEMFCs: the oxygen (electro)reduction reaction (ORR) at the cathode
and the hydrogen (electro)oxidation reaction (HOR), formic acid (electro)oxidation
reaction (FOR), or methanol (electro)oxidation reaction (MOR) at the anode.
Decreasing the particle size to nanometer dimensions allows an increase in the ratio
between the number of atoms on the surface N
s
and the overall number of metal
atoms N
total
(the so-called dispersion D ¼ N
s
/N
total
), thus saving expensive precious
metals. If, for a given reaction, the specific electrocatalytic activity (i.e., the activity
Former address:
Boreskov
Institute
of
Catalysis,
Russian
Academy of
Sciences,
Pr.
Akademika
Lavrentieva 5, 630090 Novosibirsk, Russia.
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