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Fabrication of sponge-like nanoporous platinum
electrocatalysts for oxygen reduction through alloying and
dealloying processes
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Jiang Ming,Lin Xiangqin,Zhang Zhixiang
Department of Chemistry,University of Science and Technology of China,Hefei (230026)
E-mail:xqlin@ustc.edu.cn
Abstract
A novel sponge-like spherical nanoporous platinum (NPs-Pt) was generated through a facile way of
electrodeposition followed by chemical etching at room temperature. First, a Pt-Cu alloy nanoparticles
was electrodeposited on a glassy carbon electrode (GCE) using cyclic voltammetry (CV), and then Cu
was etched off from the alloy in HNO
3
. FE-SEM, XPS, EIS and CV were used for characterization.
Optimal conditions for the preparation were investigated. The NPs-Pt modified electrode (NPs-Pt/GCE)
exhibited excellent electrocatalytic activity toward the oxygen reduction reaction (ORR). Moreover, the
peak current of ORR at NPs-Pt/GCE was 4 times higher than that correspondingly prepared Pt
nanoparticles modified electrode, showing much higher current sensitivity. The preparation method for
the sponge-like nanoporous structure and the NPs-Pt modified electrode can be expected to have
promising applications in the field of fuel cells and biosensors, etc.
Keywords: Nanoporous Pt; dealloying; Pt-Cu alloy; oxygen reduction reaction
1. Introduction
Electrochemical reduction of oxygen has shown importance for extensive studies in many fields.
The specific areas of interest include the quantitative analysis of oxygen concentration, the
monitoring of enzymatic reactions and energy generation etc. Especially, this reaction plays a vital
role in electrochemical energy-conversion systems, such as metal-air batteries and fuel cells [1-3],
which may be considered as green power sources for applications in the transportation arena, due
to their high energy density, relatively low operating temperatures, low emission of pollutants, and
minimal corrosion problems [4-6]. At a reasonably low overpotential is the ultimate goal of many
investigations, so the reduction of molecular oxygen is commonly achieved by a platinum-loaded
high surface area electrode [7] because of the superior catalytic activity of platinum. However, the
performance of the Pt electrode is still limited at high potentials due to the formation of adsorbed
species on the electrode surface [8, 9]. This limitation imposes a significant loss in the overall
performance of the fuel cells. Many researchers have shown a considerable interest in using
nanostructured Pt film for improving the catalytic activity, which can be prepared based on liquid
crystal templates [10-12], hydrothermal-assisted seed growth [13] and electrochemical dealloying
[14,15]. The liquid crystal template techniques have the advantage of control over the size of the
porous structure, but are generally difficult and time-consuming to implement. The
hydrothermal-assisted seed method is also time-consuming.
Nanostructured Pt and bimetallic alloys, such as Pt-Fe, Pt-Ni, Pt-Co, Pt-V, Pt-Mn and Pt-Cr
[16-21], have been extensively studied and display the enhanced electrocatalytic activity to pure Pt
with low Pt amount. The improvement in the ORR electrocatalysis on Pt alloy catalysts has been
explained by several factors such as electronic and structural effects [18, 22]. Although Pt-based
alloys are important catalysts for fuel cell applications, however, how to improve the utilization
and efficiency of the Pt-based anodic materials is still a challenge [23]. Since surface-catalyzed
reactions are extremely sensitive to the details of the catalytic surface [24], the deliberate tailoring
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Supported by the Specialized Research Fund for the Doctoral Program of Higher Education (No. 20040358021).