Vol. 25, No. 5, 2014
Geraldes et al.
839
atoms, on a carbon diffusion layer. The modification of
palladium surface by gold atoms leads to an increase in
the catalytic activity towards glycerol electrooxidation.
The PdAu alloy surface composition has no significant
effect on the catalytic activity; however, the presence of
non-alloyed gold sites on the material surface leads to
the enhancement of the catalytic activity. The mechanism
seems to involve glycerol adsorption on palladium surface
and hydroxyl species formation on gold surface, leading
to catalytic activity enhancement through the bifunctional
mechanism. Ilie et al.13 tested the commercial anionic
membrane Fumapem® FAA (FuMA-Tech). The tests were
performed in a 5 cm2 cell with identical anode and cathode
(Pt (40 wt.%)/C, 2 mg Pt cm-2 deposited on a diffusion
layer carbon cloth with PTFE (15 wt.%)/C). The used
fuel composition was 1.0 mol L-1 glycerol/4.0 mol L-1
NaOH, and oxygen was used as oxidant. The power
densities achieved with the FuMA-Tech membrane was
13.5 mW cm-2 at 60 °C, and 7.8 mW cm-2 at 25 °C.
It is assumed that the reactions involved in an
ADGFC working with glycerol-KOH fuel occur with
higher kinetics than those in acid fuel cell. Under these
circumstances, the possibility of either decreasing the
Pt loading or even using non-platinum-based catalysts
may be considered. The literature shows that some Pt-
based and Pd-based catalysts displayed high catalytic
activity for alcohol or polyol electrooxidation in alkaline
medium.13,15,27,34 Moreover, Pd-based bimetallic catalysts
seem to be more stable with respect to degradation than
pure Pd on carbon black.13,35,36
and the maximum power density was 22 mW cm-2 while for
2.0 mol L-1 glycerol the best composition was Pd:Au 90:10
and the maximum power density was 34 mW cm-2.
Acknowledgments
The authors wish to thank FAPESP (2012/03516-5,
2013/01557-0), CNPq (162669/2013-5, 474913/2012-0,
406612/2013-7), Instituto Nacional de Ciência e Tecnologia
(INCT) de Energia e Meio Ambiente (Process Number.
573.783/2008-0) and UFABC for their financial support,
CTR and CCTM from IPEN/CNEN-SP for electron beam
irradiations and TEM measurements.
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