1D Pd-Based Nanomaterials as Efficient Electrocatalysts for Fuel Cells - Low-cost Nanomaterials: Toward Greener and More Efficient Energy Applications - page 338

(a)

0.16

(c) 400

0.14

0.12

200

0.10

0.08

0

0.06

-200

0.04

0.02

-400

Pd-25
Pd-100
Bulk Pd(x5)

4.0

(d)

3.5

-600

bulk Pd
Pd-25/GC
Pd-100/GC

3.0

-0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0

2.5

2.0

E (V vs Ag/AgCl)

1.5

(b)

1.0

7

0.5

6

Pd-25/GC
in 0.1M HClO 4
Pd-25/GC
Pd-100/GC
bulk Pd

0.0

(e)

5

1.0

4

0.8

3

0.6

2

0.4

1

0.2

0

0.0

0 100 200 300 400

-0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4

t (s)

E(V vs Ag/AgCl)

Fig. 19 a Cyclic voltammograms of the PdAg-25/GC (black curve), PdAg-100/GC (red curve),
and bulk Pd electrode (blue curve) in 0.1 M HClO 4 solution. For comparison, the CV from the Pd
bulk electrode is magnified 59. b CVs of the PdAg-25/GC (red curve), PdAg-100/GC (green
curve), and bulk Pd electrode (blue curve) electrodes in 0.1 M HClO 4 and 0.5 M HCOOH
solution and the CV of PdAg-25/GC (black curve) in 0.1 M HClO 4 . Potential scan rate 0.1 V s -1 .
Chronoamperometric curves of the bulk Pd, PdAg-25/GC and PdAg-100/GC electrodes in 0.1 M
HClO 4 + 0.5 M HCOOH at different electrode potentials: c -0.15, d +0.3, and e +0.68 V.
Reprinted from Ref. [ 76 ] with permission by the American Chemical Society

show that worm-like nanowires were formed and the surface of the nanowires is
predominated by Pd(111) planes. As mentioned previously, the (111) planes of Pd
are less susceptible to oxidation and have a lower peak potential for formic acid
oxidation, making the nanowires promising electrocatalysts for DFAFCs. The
element maps revealed that the elements of Pd and Ag are homogeneously dis-
persed in the PdAg nanowires, indicating the formation of alloy structure. The
electrochemical studies showed that although the onset potential of formic acid
oxidation on PdAg nanowires is only a little more negative than that on the
commercial Pd/C catalyst, the current density of formic acid oxidation in both
forward and reverse potential sweeps is much larger (about 3.4 times) than that
obtained at the Pd/C. Moreover, from the CV and chronoamperometric mea-
surements, our synthesized PdAg nanowires exhibit high CO tolerance and