Comparison of Pd–Co–Au electrocatalysts prepared by conventional borohydride and microemulsion methods for oxygen reduction in fuel cells

Raghuveer, V.; Ferreira, Paulo J.; Manthiram, Arumugam

doi:10.1016/j.elecom.2006.03.022

Cited by 112 publications

(88 citation statements)

References 25 publications

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“…It is also observed that the average particle size is slightly higher than the untreated one ͑figure not shown͒ and the heat-treatment appears to favor agglomeration as reported earlier. 35,39 It is also noted that a few larger sized particles ͑Ͼ40 nm͒ are also observed, which are formed due to aggregation of the particles at higher temperatures. The particle sizes obtained from the images are in agreement with those calculated from the XRD ͑200͒ peaks using Scherrer equation ͑Table I͒.…”

Section: Methodsmentioning

confidence: 99%

“…Palladium alloys with Co, Cr, Fe, Mo, Ti, Au, and Ni have shown catalytic activity close to that of platinum, giving scope for replacing the latter. [30][31][32][33][34][35][36][37][38][39][40][41][42] These nonprecious metal catalysts present a viable alternative to noble-metal catalysts provided they demonstrate substantial activity and long-term operational stability.Though non-noble metal alloy catalysts are explored as methanol tolerant ORR catalysts, their activity towards ORR is still lower than Pt-C as reported in the literature. 33,36 Further, the nonprecious metal catalysts do not match the performance of conventional platinum in the sense of low ORR kinetics and stability in the acidic environment and hence it is very difficult to avoid the loading of the precise metal in the cathode.…”

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confidence: 99%

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confidence: 99%

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Carbon-Supported Palladium-Cobalt-Noble Metal (Au, Ag, Pt) Nanocatalysts as Methanol Tolerant Oxygen-Reduction Cathode Materials in DMFCs

Mathiyarasu

Phani

2007

J. Electrochem. Soc.

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The carbon-supported nanoparticles of Pd-Co-M ͑M = Pt, Au, Ag͒ catalysts for direct methanol fuel cells ͑DMFCs͒ in a ratio of ͑70:20:10͒ were prepared through reverse microemulsion method. The X-ray diffraction ͑XRD͒ analysis showed well-defined reflections corresponding to a face centered cubic phase of palladium. From transmission electron microscopy analysis, the particle size after heat-treatment at 500°C was found to be approximately 20 nm, which was also confirmed by XRD analysis. Polarization data indicated Pd-Co-Pt to have better oxygen reduction reaction ͑ORR͒ activity than the other combinations with Ag and Au, in terms of shift in onset potential to a positive value of more than 100 mV and increased reduction current. The ORR kinetics on Pd-Co-Pt was analyzed by using rotating disk electrode to follow a 4 electron pathway, the order of the reaction being unity. The peroxide formation estimated from the rotating ring disk electrode measurements was found to be a negligibly small amount of 1.1%. An additional advantage observed with Pd-Co-Pt was its high methanol tolerance and ORR activity nearly equal to Pt. The major problem which concerns the developments in the direct methanol fuel cells ͑DMFCs͒ is the crossover of methanol through the polymer electrolyte membrane to the cathode compartment.1 This results in establishment of mixed potentials and depolarization of cathode potential, reduction of cell power and conversion losses due to fuel loss. [2][3][4][5][6][7][8][9] The simultaneous reduction of oxygen and suppression of fuel oxidation at the cathode requires electrode materials selective to oxygen reduction reaction ͑ORR͒ and further the catalyst should be tolerant to methanol.Therefore efforts are under way in developing new generation electrocatalysts to address these problems, by examining the requirements for selective ORR and improvements in the electrocatalytic characteristics. Platinum is the best known cathode catalyst, which has not been replaced by other materials so far. But the problem with the Pt catalyst is the high affinity towards adsorption of methanol on its surface. This leads to the catastrophic loss in the performance of DMFCs. Hence, Pt catalyst materials are developed by suitably alloying with secondary elements and studies have shown that platinum-based binary alloyed electrocatalysts such as PtFe, PtCo, PtNi, PtBi, and PtCr exhibit a higher catalytic activity for ORR in acid electrolytes than pure platinum. [10][11][12][13][14][15][16][17][18][19][20][21][22] These catalysts have already shown nearly the same activity for the ORR in the absence as well as in the presence of methanol.Recent research has shown the practicality of using nonplatinum metal alloys for ORR with resistance to methanol oxidation. Several nonplatinum electrocatalysts are reported for their adequate oxygen reduction activity to be considered as potential catalysts in commercial fuel cell applications. Nonprecious catalysts such as metal phthalocyanines, 23,24 transition metalloporphyrins, 25,26 tra...

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Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Carbon-Supported Palladium-Cobalt-Noble Metal (Au, Ag, Pt) Nanocatalysts as Methanol Tolerant Oxygen-Reduction Cathode Materials in DMFCs

Mathiyarasu

Phani

2007

J. Electrochem. Soc.

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“…Cathodic catalysts to be used in fuel cells are also reported to be synthesized via microemulsion route [83]. Yet, the microemulsion-synthesized nanocatalysts exhibit unsatisfactory long-term stability [84]:…”

Section: Electrocatalysismentioning

confidence: 99%

Microemulsion Route for the Synthesis of Nano-Structured Catalytic Materials

Hussain¹,

Batool²

2017

Properties and Uses of Microemulsions

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Owing to their unique properties, use of microemulsion-based synthetic techniques for the generation of shape-controlled nanocatalyst is an area of great current interest. Nanocatalysts of any specific shape, morphology, surface area, size, geometry, homogeneity and composition are widely being prepared using the soft techniques of microemulsion. Easy handling, inexpensive equipment and mild reaction conditions make microemulsion an attractive reaction medium. Herein, a nanosized precursor reactant can be incorporated, leading to the formulation of a highly monodispersed metal nanoagglomerate with controlled size, shape and composition. Several factors such as presence of electrolyte, molar ratio of water to surfactant, nature and concentration of surfactant and solvent, size of water droplets and concentration of reducing agents influence the size of the nanoparticles. The reverse micelle method can be used for the fabrication of several nanosized catalysts with a diverse variety of suitable materials including silica, alumina, metals (e.g. Au, Pd, Rh, Pt), metal oxides, etc. The morphology, size distribution and shape of the nanocatalysts make them useable for a wide range of applications, for example, fuel cells, electrocatalysis, photocatalysis, environmental protection, etc. The recovery of nanoparticles from the reaction mixture is a challenge for the researchers. This chapter discusses the preparation of nanoparticles using microemulsion techniques, widely being used for the synthesis of nanocatalysts from a wide range of materials.

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“…[1][2][3] Recently, alloying of Pd of which the cost is only one-fifth of Pt with other elements has been found to show high catalytic activity for ORR. [4][5][6][7][8][9] Among them, the PdCo alloys are particularly interesting as they exhibit high catalytic activity for ORR and also good tolerance to methanol. 4,10) Many researchers reported that the particle size, dispersion, and compositional homogeneity of the alloy clusters on the carbon support are important factors to obtain good catalytic activity.…”

Section: Introductionmentioning

confidence: 99%

Fine Structure Effect of PdCo electrocatalyst for Oxygen Reduction Reaction Activity: Based on X-ray Absorption Spectroscopy Studies with Synchrotron Beam

Kim¹,

Kim²,

Kim³

et al. 2010

Journal of Electrochemical Science and Technology

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:In this study, we have demonstrated the fine structure effect of PdCo electrocatalyst on oxygen reduction reaction activity with different alloy composition and heat-treatment time. In order to identify the intrinsic factors for the electrocatalytic activity, various X-ray analyses were used, including inductively coupled plasma-atomic emission spectrometer, transmission electron microscopy, X-ray diffractometer, and X-ray Absorption Spectroscopy technique. In particular, extended X-ray absorption fine structure was employed to extract the structural parameters required for understanding the atomic distribution and alloying extent, and to identify the corresponding simulated structures by using FEFF8 code and IFEFFIT software. The electrocatalytic activity of PdCo alloy nanoparticles for the oxygen reduction reaction was evaluated by using rotating disk electrode technique and correlated to the change in structural parameters. We have found that Pd-rich surface was formed on the Co core with increasing heating time over 5 hours. Such core shell structure of PdCo/C showed that a superior oxygen reduction reaction activity than pure Pd/C or alloy phase of PdCo/C electrocatalysts, because the adsorption energy of adsorbates was apparently reduced by lowering the dband center of the Pd skin due to a combination of the compressive strain effect and ligand effect.

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Comparison of Pd–Co–Au electrocatalysts prepared by conventional borohydride and microemulsion methods for oxygen reduction in fuel cells

Cited by 112 publications

References 25 publications

Carbon-Supported Palladium-Cobalt-Noble Metal (Au, Ag, Pt) Nanocatalysts as Methanol Tolerant Oxygen-Reduction Cathode Materials in DMFCs

Carbon-Supported Palladium-Cobalt-Noble Metal (Au, Ag, Pt) Nanocatalysts as Methanol Tolerant Oxygen-Reduction Cathode Materials in DMFCs

Microemulsion Route for the Synthesis of Nano-Structured Catalytic Materials

Fine Structure Effect of PdCo electrocatalyst for Oxygen Reduction Reaction Activity: Based on X-ray Absorption Spectroscopy Studies with Synchrotron Beam

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