Characterization and application of electrodeposited Pt, Pt/Pd, and Pd catalyst structures for direct formic acid micro fuel cells

Jayashree, Ranga S.; Spendelow, Jacob S.; Yeom, Junghoon; Rastogi, Chandan; Shannon, Mark A.; Kenis, Paul J. A.

doi:10.1016/j.electacta.2005.02.018

Cited by 194 publications

(105 citation statements)

References 23 publications

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“…5 They observed that the presence of adsorbed palladium on Pt(100) decreases selfpoisoning and lowers the oxidation potential considerably. The multi-metallic nanoparticle catalysts, however, were usually prepared by co-precipitation 6 or electrodeposition 7 , and control over surface structure was not achieved. We present the synthesis and application of binary Pt/Pd nanoparticles in which Pd decorates the well-defined surface of Pt nanoparticles.…”

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confidence: 99%

Localized Pd Overgrowth on Cubic Pt Nanocrystals for Enhanced Electrocatalytic Oxidation of Formic Acid

et al. 2008

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Single crystalline surface such as (100), (111), (110) has been studied as an idealized platform for electrocatalytic reactions since the atomic arrangement affects a catalytic property. The secondary metal deposition on these surfaces also alters the catalytic property often showing improvement such as poisoning decrease. On the other hand, electrocatalysts used for practical purpose usually have a size on the order of nanometers. Therefore, linking the knowledge from single crystalline studies to nanoparticle catalysts is of enormous importance. Recently, the Pt nanoparticles which surface structure was preferentially oriented was synthesized and used as electrocatalysts 12 . Here, we demonstrate a rational design of a binary metallic nanocatalyst based on the single crystalline study.Clavilier et al. studied the electro-oxidation of formic acid for Pd adsorbed on Pt(100) single crystal surfaces. 5 They observed that the presence of adsorbed palladium on Pt(100) decreases selfpoisoning and lowers the oxidation potential considerably. The multi-metallic nanoparticle catalysts, however, were usually prepared by co-precipitation 6 or electrodeposition 7 , and control over surface structure was not achieved. We present the synthesis and application of binary Pt/Pd nanoparticles in which Pd decorates the well-defined surface of Pt nanoparticles. Pt nanocubes fully bound by (100) surfaces acted as seeds for overgrowth of Pd. Overgrowth was observed at multiple points on each seed, predominantly at the corners. Electro-oxidation of formic acid performed on these binary Pt/Pd catalysts showed the same effects of less poisoning and lower oxidation potential expected from the single crystal study.Preparation of metal nanoparticles with shape control has often been achieved by controlling growth rates on different facets through interactions with surface-stabilizing agents. 8 However, since the catalytic activity is hindered by these surface-stabilizing agents, 9 preserving the catalytic activity of the metal surface is crucial. In this study, we used tetradecyltrimethylammonium bromide (TTAB) as a surface-stabilizing agent since it has a weak interaction with metal surfaces 9a . The cubic Pt nanoparticles used as seeds were prepared by reducing K 2 PtCl 4 dissolved in aqueous TTAB solution with NaBH 4 as previously reported. 9a A TEM image of the cubic Pt seed particles is shown in Figure S1(a). Pd was nucleated on the surface of cubic Pt seeds upon reduction of K 2 PdCl 4 by ascorbic acid in the presence of TTAB (See Supporting Information for more details). Figure 1(a) shows a low magnification TEM image of the binary Pt/Pd nanoparticles. Single, double and multiple nucleation of Pd on Pt nanoparticles was observed with nucleation occurring primarily on the corners. High resolution TEM images in Figures 1(b) show the interface of the two metals more clearly. Pd grew on Pt surface epitaxially. Figure 1(c) and (d) show a high and low coverage of Pd on Pt surface. The formation of multiple nucleation sites of Pd on the ...

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Localized Pd Overgrowth on Cubic Pt Nanocrystals for Enhanced Electrocatalytic Oxidation of Formic Acid

et al. 2008

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“…Noble metals (mainly Pt) have often been employed as the catalysts in fuel cells. 6 Recent studies have shown that Pt-based alloy catalysts [7][8][9][10][11][12][13][14][15] exhibit greater catalytic activities for the electrooxidation of small organic fuels such as methanol and formic acid due to the so-called bifunctional mechanism [16][17][18] or electronic (ligand) effect. 7,19 In order to further reduce the costs of catalysts, either less expensive non-noble metal catalysts have to be used or the loading of the noble metals on the electrode surface has to be reduced, and at the same time, the catalytic performance and utilization efficiency of electrocatalysts remain uncompromised.…”

Section: Introductionmentioning

confidence: 99%

Langmuir−Blodgett Thin Films of Fe₂₀Pt₈₀ Nanoparticles for the Electrocatalytic Oxidation of Formic Acid

Chen

Kim

et al. 2007

J. Phys. Chem. C

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The electro-oxidation of formic acid catalyzed by Fe 20 Pt 80 nanoparticles was studied by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) where the particles were deposited onto a gold electrode surface by the Langmuir-Blodgett (LB) technique at varied film thickness/coverage. It was found that the particle assembly thickness strongly affected the electrocatalytic activity for HCOOH oxidation. For a single monolayer and two layers of FePt particles, extensive CO adsorption (poisoning) was observed in CV measurements, whereas with a four-layer assembly of the FePt particles, the tolerance to CO poisoning improved drastically. Furthermore, from the current density for formic acid oxidation, the electrodes functionalized with LB layers of nanoparticles exhibited higher activities than those with dropcast films of similar thickness, suggesting the importance of the ordering of the particle layers in the electrocatalytic performance. The reaction kinetics in the HCOOH oxidation on the three kinds of particle film-modified electrodes was then examined by EIS measurements. It was found that except within the potential range for CO oxidation, the impedance spectra behaved normally with the responses shown in the first quadrant for all three nanoparticle assemblies under study, indicative of only resistive and capacitive components in the electrochemical cell. In contrast, at potentials of CO electro-oxidation, the impedance spectra were found to migrate from the first quadrant to the second quadrant and then back to the first quadrant with increasing electrode potential, which suggests that the reaction kinetics evolve from resistive to pseudoinductive and then to inductive behaviors. The different EIS behaviors are ascribed to the different degree of tolerance to CO poisoning, consistent with the voltammetric results.

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“…Among others, nanoporous palladium is a promising material for catalytic application, 12) hydrogen sensing 13) and hydrogen storage, 14) offering a large surface area. Typical and conventional nanoporous Pd is Pd black, which is composed of coagulated Pd nanoparticles having several hundred nanometer diameters.…”

Section: Introductionmentioning

confidence: 99%

Preparation of Nanoporous Palladium by Dealloying: Anodic Polarization Behaviors of Pd-M (M=Fe, Co, Ni) Alloys

Hakamada

Mabuchi

2009

Mater. Trans.

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Anodic polarization behaviors of Pd-M (M ¼ Fe, Co, Ni) alloys in H 2 SO 4 solution are investigated for the preparation of nanoporous palladium by dealloying. For Pd 0:2 Co 0:8 alloy, the current monotonically increased with the increase in potential. However, anodic polarization curves for Pd 0:2 Fe 0:8 and Pd 0:2 Ni 0:8 alloys showed passive regions at high potentials, although the standard electrode potentials for Fe, Co, Ni are similar. As a result, nanoporous Pd was successfully fabricated via electrolysis under a constant potential (¼ þ0:5 V vs standard calomel electrode) only when the starting alloy was Pd-Co. Passivation, as well as standard electrode potentials, must be considered for the efficient production of nanoporous Pd. The preparation of nanoporous structure on the surface of bulk Pd was also demonstrated using alloying/ dealloying process involving Co electrodeposition, thermal alloying and subsequent dealloying.

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Characterization and application of electrodeposited Pt, Pt/Pd, and Pd catalyst structures for direct formic acid micro fuel cells

Cited by 194 publications

References 23 publications

Localized Pd Overgrowth on Cubic Pt Nanocrystals for Enhanced Electrocatalytic Oxidation of Formic Acid

Localized Pd Overgrowth on Cubic Pt Nanocrystals for Enhanced Electrocatalytic Oxidation of Formic Acid

Langmuir−Blodgett Thin Films of Fe₂₀Pt₈₀ Nanoparticles for the Electrocatalytic Oxidation of Formic Acid

Preparation of Nanoporous Palladium by Dealloying: Anodic Polarization Behaviors of Pd-M (M=Fe, Co, Ni) Alloys

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Characterization and application of electrodeposited Pt, Pt/Pd, and Pd catalyst structures for direct formic acid micro fuel cells

Cited by 194 publications

References 23 publications

Localized Pd Overgrowth on Cubic Pt Nanocrystals for Enhanced Electrocatalytic Oxidation of Formic Acid

Localized Pd Overgrowth on Cubic Pt Nanocrystals for Enhanced Electrocatalytic Oxidation of Formic Acid

Langmuir−Blodgett Thin Films of Fe20Pt80 Nanoparticles for the Electrocatalytic Oxidation of Formic Acid

Preparation of Nanoporous Palladium by Dealloying: Anodic Polarization Behaviors of Pd-M (M=Fe, Co, Ni) Alloys

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Langmuir−Blodgett Thin Films of Fe₂₀Pt₈₀ Nanoparticles for the Electrocatalytic Oxidation of Formic Acid