8 research outputs found
Synthesis and Growth Mechanism of Ni Nanotubes and Nanowires
Highly ordered Ni nanotube and nanowire arrays were fabricated via electrodeposition. The Ni microstructures and the process of the formation were investigated using conventional and high-resolution transmission electron microscope. Herein, we demonstrated the systematic fabrication of Ni nanotube and nanowire arrays and proposed an original growth mechanism. With the different deposition time, nanotubes or nanowires can be obtained. Tubular nanostructures can be obtained at short time, while nanowires take longer time to form. This formation mechanism is applicable to design and synthesize other metal nanostructures and even compound nanostuctures via template-based electrodeposition
Oxygen Reduction Reaction on Electrodeposited Pt<sub>100–<i>x</i></sub>Ni<sub><i>x</i></sub>: Influence of Alloy Composition and Dealloying
The electrocatalytic activity of electrodeposited Pt<sub>100–<i>x</i></sub>Ni<sub><i>x</i></sub> thin films toward
the oxygen reduction reaction (ORR) in perchloric acid was studied
for <i>x</i> ranging between 2 and 95. The alloy composition
was controlled by the potential applied during deposition. XRD and
EDS were used to examine the structure and composition of the films
before and after ORR measurements. Significant dealloying was evident
for films with <i>x</i> > 45, and substantial shrinkage
of the film thickness accompanied dealloying for films with <i>x</i> > 55. The onset of significant shrinkage occurs near
the
parting limit reported for bulk dealloying of fcc solid solutions.
A maximum ORR specific activity of 2.8 mA/cm<sup>2</sup> at 0.900
V RHE was observed for alloys between Pt<sub>45</sub>Ni<sub>55</sub> and Pt<sub>55</sub>Ni<sub>45</sub>. This represents an enhancement
factor of 4.7 compared to electrodeposited Pt, thereby matching the
best published results reported for Pt–Ni nanoparticles and
thin films. A peak ORR mass activity of 0.78 A/mg<sub>Pt</sub> at
0.900 V RHE was observed for alloy film compositions between Pt<sub>38</sub>Ni<sub>62</sub> and Pt<sub>45</sub>Ni<sub>55</sub>. In comparison
to electrodeposited Pt, these films exhibit a 10-fold improvement
in mass activity