Stabilization of Platinum Oxygen-Reduction Electrocatalysts Using Gold Clusters

Chemistry Department, Brookhaven National Laboratory, New York, New York, United States
Science (Impact Factor: 33.61). 02/2007; 315(5809):220-2. DOI: 10.1126/science.1134569
Source: PubMed


We demonstrated that platinum (Pt) oxygen-reduction fuel-cell electrocatalysts can be stabilized against dissolution under potential cycling regimes (a continuing problem in vehicle applications) by modifying Pt nanoparticles with gold (Au) clusters. This behavior was observed under the oxidizing conditions of the O2 reduction reaction and potential cycling between 0.6 and 1.1 volts in over 30,000 cycles. There were insignificant changes in the activity and surface area of Au-modified Pt over the course of cycling, in contrast to sizable losses observed with the pure Pt catalyst under the same conditions. In situ x-ray absorption near-edge spectroscopy and voltammetry data suggest that the Au clusters confer stability by raising the Pt oxidation potential.

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    • "The cathodic oxygen reduction reaction (ORR), O 2 + 4H + + 4e –   2H 2 O, is one of the most important electrochemical reactions due to its prominent role in renewable-energy technologies, such as fuel cells and metal–air batteries [1] [2] [3] [4] [5]. The electrocatalyst involved in the ORR plays a vital role in determining the performance of the energy devices, including power output, charge–discharge rate, energy efficiency, and cycling life [6] [7]. "
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    ABSTRACT: Cathodic oxygen reduction reaction (ORR) is a highly important electrochemical reaction in renewable-energy technologies. In general, the surface area, exposed facets and electrical conductivity of catalysts all play important roles in determining their electrocatalytic activities, while their performance durability can be improved by integration with supporting materials. In this work, we have developed a method to synthesize hybrid structures between PtPd bimetallic nanocages and graphene by employing selective epitaxial growth of single-crystal Pt shells on Pd nanocubes supported on reduced graphene oxide (rGO), followed by Pd etching. The hollow nature, {100} surface facets and bimetallic composition of PtPd nanocages, together with the good conductivity and stability of graphene, enable high electrocatalytic performance in ORR. The obtained PtPd nanocage–rGO structures exhibit mass activity (0.534 A·mg Pt −1 ) and specific activity (0.482 mA·cm−2) which are 4.4 times and 3.9 times greater than the corresponding values for Pt/C.
    Nano Research 09/2015; 8(9):2789-2799. DOI:10.1007/s1227401507706 · 7.01 Impact Factor
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    • "An effective electrocatalyst that can accelerate both the ORR and OER is crucial for the performance improvement of metal-air batteries. Platinum and its alloy, such as Pt/Au and Pt/Ir, have shown excellent bi-functional electrocatalytic activity for ORR and OER [8] [9] [10]. However, they suffer from the high price and low abundance. "
    Electrochimica Acta 09/2015; 180:788. · 4.50 Impact Factor
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    • "Polymer electrolyte fuel cells have been extensively investigated as ideal energy sources for portable electronic devices and for electric vehicles due to their high power density and use of environmentally friendly fuels [1] [2] [3]. However, the expensive metal catalyst Pt, supported on carbon black (here using as the most common electrocatalyst (Pt/C) with 40% Pt on Vulcan 72 [4]) during operation suffers from Pt dissolution [5], Ostwald ripening [6], nanoparticle mobility and aggregation [7], and carbon support electrochemical corrosion [8] in the harsh working environment within polymer electrolyte fuel cells. This commonly leads to a rapid and significant loss of electrochemical surface area [9] (ECA). "
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    ABSTRACT: The limited stability of fuel cell cathode catalysts causes a significant loss of operational cell voltage with commercial Pt-based catalysts, which hinders the wider commercialization of fuel cell technologies. We demonstrate beneficial effects of a highly rigid and porous polymer of intrinsic microporosity (PIM-EA-TB with BET surface area 1027 m2 g- 1) in accelerated catalyst corrosion experiments. Porous films of PIM-EA-TB offer an effective protective matrix for the prevention of Pt/C catalyst corrosion without impeding flux of reagents. The results of electrochemical cycling tests show that the PIM-EA-TB protected Pt/C (denoted here as PIM@Pt/C) exhibit a significantly enhanced durability as compared to a conventional Pt/C catalyst.
    Electrochemistry Communications 08/2015; 59:72-76. DOI:10.1016/j.elecom.2015.07.008 · 4.85 Impact Factor
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