Environmental Engineering Reference
In-Depth Information
&
CHAPTER 1
Electrocatalysis of Oxygen Reduction
in Polymer Electrolyte Fuel Cells: A Brief
History and a Critical Examination of
Present Theory and Diagnostics
SHIMSHON GOTTESFELD
Cellera Technologies, Caesarea, Israel
1.1 INTRODUCTION
The title that I chose for my talk in Leiden was “Electrocatalysis—a scan over 20
years
þ
one great meeting.” Although the superlative used in the name of the talk
was chosen well before the meeting itself, it will be seen from this chapter that the
meeting indeed provided significant further food for thought, at least in the case of
this participant, regarding the fundamentals of fuel cell electrocatalysis. Of particular
interest has been the dialogue between the recent advances in the theory of electro-
catalysis and the corresponding experimental data collected to date, that should serve
as a basis for solid mechanistic conclusions and define a road map for the future. This
chapter will first describe, in line with its original assignment, key milestones in the
development of electrocatalysts for low temperature fuel cells, leading next to a discus-
sion of the state of the art in the field. Both the historical comments and, particularly,
the latter part of the chapter, devoted to a critical examination of the state of the art, are
focused on the oxygen reduction reaction (ORR). The ORR remains the most serious
challenge to both fuel cell experimentalists and theorists, as is evident from the major
contribution that the air cathode loss makes at present to the overall voltage loss of a
polymer electrolyte fuel cell (PEFC), or any other low temperature fuel cell. This is
despite the significant experimental and, particularly, theoretical advances in air
cathode electrocatalysis in PEFCs that have been made since the year
2000.
