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Introduction
The
direct ethanol fuel cells are a subcategory of the proton exchange
membrane
(PEM) fuel cells. The limitation of
hydrogen for PEM fuel cells has resulted in researchers trying other
fuels that
are directly oxidizable. The DAFC seems
most promising for portable applications such as cellular phones,
digital
cameras, and laptop computers. Ethanol
is a preferred choice in comparison with methanol since methanol is a
toxic and
harmful chemical (Nguyen et al. 507). Until
recently, most research on direct alcohol fuel cells (DAFC) has been
done in
acidic conditions with platinum catalysts. In
alkaline media, corrosion is less important and
the kinetics of the
alcohol oxidation and oxygen reduction reactions are greatly improved. In an alkaline fuel cell, OH- is
conducted from the cathode to the anode, unlike acidic fuel cells where
H+
is transmitted from the anode to the cathode (O’Hayre 266).
Traditionally,
platinum has been the catalyst for most fuel cells, specifically PEM
fuel
cells. However, nonplatinum catalysts
can be used in alkaline direct alcohol fuel cells (O'Hayre 274). It has been found that palladium is a good
catalyst for the oxidation of ethanol in alkaline solutions. One advantage of using palladium is that it
is more abundant than platinum, but it needs higher activity. Some studies have tried to improve
palladium’s activity with other metals, including cheaper metals
such as silver
(Nguyen et al. 507). The present study
focuses on pairing palladium with silver at different compositions for
characterization. The
present study deals with the investigation of three different
compositions of Ag-Pd
nanoparticles for direct ethanol fuel cell catalysts.
The molar concentration of palladium varied
while the silver molar concentration remained constant.
One goal of the study is to analyze the
composition of the samples and compare to the initial synthesis ratios
of Ag to
Pd. Another goal is to determine if the
Ag-Pd nanoparticles are hollow. Hollow
nanoparticles would be extremely beneficial for saving materials and
costs.
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