Environmental Engineering Reference
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Fig. 17 a CVs of the Pd
x
Pt
y
electrodes in a 0.5 M NaOH + 1 M ethanol solution; b CVs of the
Pd
45
Pt
55
, Pd NWs, Pt NTs and E-TEK Pd/C electrodes in a 0.5 M NaOH + 1 M ethanol solution;
c Current density-time curves of the Pd
45
Pt
55
, Pd NWs, Pt NTs and E-TEK Pd/C electrodes in a
0.5 M NaOH + 1 M ethanol solution at -0.2 V; d CVs of the Pd
45
Pt
55
, Pd NWs, Pt NTs and
E-TEK Pd/C electrodes in a 1 M KOH + 1 M methanol solution; e Current density-time curves
of the Pd
45
Pt
55
, Pd NWs, Pt NTs and E-TEK Pd/C electrodes in a 1 M KOH + 1 M methanol
solution at -0.2 V. The loading amount of noble metal is 71.4 lgcm
-2
for each catalyst and all
the potential scan rates are 50 mV s
-1
. Reprinted from Ref. [
64
] with permission by Wiley-VCH
monometallic catalysts Pt NTs and Pd NWs and the commercial E-TEK Pd/C
catalyst toward methanol oxidation in alkaline conditions (Fig.
17
d, e). The
excellent catalytic performance of the PdPt nanowires could be attributed to three
aspects: (1) the high aspect ratio; (2) the electronic effect; and (3) the synergistic
effect [
64
].
3.2 Electrocatalysts for Formic Acid Oxidation
Except for alcohol, formic acid is another potential fuel for liquid fuel cells.
Formic acid is a liquid at room temperature and dilute formic acid is on the US
Food and Drug Administration list of food additives. Although the energy density
of formic acid is lower than that of methanol, formic acid can be oxidized at less
positive potential and with faster kinetics than methanol at room temperature.
Moreover, formic acid can be easily handled and stored, and the low crossover
through the polymer membranes allows fuel cells to work at relatively high
concentrations of fuel and thin membranes. Therefore direct formic acid fuel cells
(DFAFCs) have attracted increasing attention in recent years. Three possible
reaction paths of formic acid oxidation have been widely accepted [
107
-
110
].
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