Oxygen Reduction Activity of Vapor-Grown Platinum Nanotubes

Papandrew, Alexander B.; Atkinson, Robert W.; Goenaga, Gabriel A.; Kocha, Shyam S.; Zack, Jason W.; Pivovar, Bryan S.; Zawodzinski, Thomas A.

doi:10.1149/2.090308jes

Cited by 28 publications

(32 citation statements)

References 21 publications

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“…Starting with the seminal work of Gloaguen et al (1), a number of papers have reported on the activity of various electrocatalysts measured as thin film RDEs with a few refinements of the technique over a couple of decades. (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17). The RDE system is very different from typical PEMFC set-ups and absolute values of electrocatalyst activity in the two systems differ significantly as expected.…”

Section: Introductionmentioning

confidence: 73%

Enhanced Oxygen Reduction Activity on Pt/C for Nafion-free, Thin, Uniform Films in Rotating Disk Electrode Studies

2013

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Commercially available nanoparticle platinum on high surface area carbon black (Pt/HSC) electrocatalysts were characterized in rotating disk electrode (RDE) setups using varying ink formulations and film drying techniques in an attempt to obtain thin, uniform films and reproducible activity. Electrodes prepared from Nafion-free inks that were dried under an isopropyl alcohol (IPA) atmosphere produced uniform, thin films at low electrocatalyst loadings of ~4.5 µg/cm 2 Pt . These Nafion-free/IPAdried electrodes were found to exhibit oxygen reduction reaction (ORR) activities higher than conventional Nafion-based/Air-dried electrodes by a factor of ~2.8. The magnitude of mass and specific activities were determined to be i m~7 71 ±56 mA/mg Pt and i s~8 12 ±59 mA/cm 2 Pt respectively and appear to be the highest values reported for RDE measurements on Pt/HSC in 0.1M HClO 4 at 20 mV/s and 25 o C . Electrochemical diagnostics including ORR I-V profiles, cyclic voltammograms and electrochemical impedance spectroscopy (EIS) studies were conducted to investigate the thin film Pt/HSC electrodes and correlate results to film morphology and electrochemical activity. IntroductionRotating disk electrode (RDE) experiments incorporating bulk smooth electrode tips have been utilized for half a century to estimate the electrochemical activity of electrocatalysts under controlled mass transport conditions. The use of thin-film electrodes (electrocatalyst inks deposited on glassy carbon (GC)) has gained popularity as novel electrocatalysts are often synthesized in mg quantities and therefore well-suited for evaluation/screening prior to scale-up and expensive evaluation in actual proton exchange membrane fuel cells (PEMFCs). Starting with the seminal work of Gloaguen et al.(1), a number of papers have reported on the activity of various electrocatalysts measured as thin film RDEs with a few refinements of the technique over a couple of decades. (2-17). The RDE system is very different from typical PEMFC set-ups and absolute values of electrocatalyst activity in the two systems differ significantly as expected. Nevertheless, the trends in activity for different catalysts have been found to be the same and results from RDE are a reasonable predictor of electrocatalyst activity in PEMFCs. 10.1149/05801.0015ecst ©The Electrochemical Society ECS Transactions, 58 (1) 15-26 (2013) 15 ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 130.113.151.253 Downloaded on 2015-03-17 to IPSome of the major issues and concerns regarding the evaluation of electrocatalytic activity in RDE systems are: i) researchers often utilize different RDE ink compositions and measurement protocols and obtain differing activity results that are difficult to compare between laboratories ii) the incorporation of small amounts of Nafion in the catalyst layer of RDEs contributes towards obtaining well-dispersed inks and electrodes that demonstrate reproducible results with high ECAs; however, t...

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Section: Introductionmentioning

confidence: 73%

Enhanced Oxygen Reduction Activity on Pt/C for Nafion-free, Thin, Uniform Films in Rotating Disk Electrode Studies

2013

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“…Our group has previously vapor deposited porous platinum nanotubes using this technique, which demonstrated very high specific activity, comparable to that of bulk polycrystalline platinum, for the oxygen reduction reaction. 27 Here, we demonstrate the extended capacity of this vapor deposition method for the synthesis and thermal evolution of bimetallic nanostructures by detailing the synthesis of platinum−ruthenium nanotubes.…”

Section: Introductionmentioning

confidence: 95%

Vapor Synthesis and Thermal Modification of Supportless Platinum–Ruthenium Nanotubes and Application as Methanol Electrooxidation Catalysts

Atkinson

Unocic²,

Unocic³

et al. 2015

ACS Appl. Mater. Interfaces

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Metallic, mixed-phase, and alloyed bimetallic Pt-Ru nanotubes were synthesized by a novel route based on the sublimation of metal acetylacetonate precursors and their subsequent vapor deposition within anodic alumina templates. Nanotube architectures were tuned by thermal annealing treatments. As-synthesized nanotubes are composed of nanoparticulate, metallic platinum and hydrous ruthenium oxide whose respective thicknesses depend on the sample chemical composition. The Pt-decorated, hydrous Ru oxide nanotubes may be thermally annealed to promote a series of chemical and physical changes to the nanotube structures, including alloy formation, crystallite growth, and morphological evolution. Annealed Pt-Ru alloy nanotubes and their as-synthesized analogs demonstrate relatively high specific activities for the oxidation of methanol. As-synthesized, mixed-phase Pt-Ru nanotubes (0.39 mA/cm(2)) and metallic alloyed Pt64Ru36NTs (0.33 mA/cm(2)) have considerably higher area-normalized activities than PtRu black (0.22 mA/cm(2)) at 0.65 V vs RHE.

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“…The sealing process causes the formation of a highly crystalline hydroxide layer on the surface of the anodic oxide, and the hydroxide layer is highly dissolution-resistant in acidic and alkaline solutions. Using these characteristic structural and chemical properties, anodic porous alumina has been widely investigated for many applications: antireflection structures [7,8], reflectors [9], memory devices [10], diodes [11], sensors [12], optical devices [13,14], nanocontainers [15], plasmonic devices [16], nano-templates [17,18], evaporation masks [19], catalyst supports [20], resist masks [21,22], and corrosion protection [23,24].…”

Section: Introductionmentioning

confidence: 99%

Fabrication of anodic porous alumina via anodizing in cyclic oxocarbon acids

Kikuchi

Nakajima

Kawashima

et al. 2014

Applied Surface Science

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The growth behavior of anodic porous alumina formed by anodizing in novel electrolyte solutions, the cyclic oxocarbon acids croconic and rhodizonic acid, was investigated for the first time. High-purity aluminum specimens were anodized in 0.1 M croconic and rhodizonic acid solutions at various constant current densities. An anodic porous alumina film with a cell size of 200-450 nm grew uniformly on an aluminum substrate by rhodizonic acid anodizing at 5-40 Am -2 , and a black, burned oxide was formed at higher current density. The cell size of the porous alumina increased with current density and corresponding anodizing voltage. Anodizing in croconic acid at 293 K caused the formation of thin anodic porous alumina films as well as black, thick burned oxides. The uniformity of the porous alumina improved by increasing the temperature of the croconic acid solution, and anodic porous alumina films with a uniform film thickness were successfully obtained. Our experimental results showed that the cyclic oxocarbon acids croconic and rhodizonic acid could be employed as a suitable electrolyte for the formation of anodic porous alumina films.Key words: Aluminum; Anodizing; Anodic Porous Alumina; Croconic Acid; Rhodizonic Acid IntroductionThe anodizing of aluminum in several different acidic solutions causes the formation of anodic porous alumina (i.e., porous anodic oxide film) with characteristic nanofeatures on aluminum substrates. Porous alumina consists of nano-scale hexagonal cells perpendicular to the substrate, and each cell possesses a nanopore at its center [1,2]. These cells are self-ordered by anodizing under appropriate electrochemical conditions, especially under a high electric field [3,4]. When anodic porous alumina is immersed in boiling distilled water after anodizing, the nanopores are filled by hydroxide (pore-sealing) [5,6]. The sealing process causes the formation of a highly crystalline hydroxide layer on the surface of the anodic oxide, and the hydroxide layer is highly dissolution-resistant in acidic and alkaline solutions. Using these characteristic structural and chemical properties, anodic porous alumina has been widely investigated for many applications: antireflection structures [7,8] [50] acid have been reported to date for the fabrication of anodic porous alumina. Oxalic and malonic acid anodizing have been reported to give rise to self-ordering behavior under suitable anodizing conditions. The organic and inorganic electrolytes used to fabricate anodic porous alumina possess low dissociation constant (pKa) in aqueous solution, except for glycolic and formic acid, are diacids or triacids. However, glycolic and formic acid form dimers via hydrogen bonding in aqueous solution and may behave like diacids [52,53]. The nanofeatures of anodic porous alumina, including cell size (i.e., interpore distance) and pore diameter, are limited by these electrolytes during anodizing. Therefore, the discovery of additional electrolytes is very important in expanding the applicability of porous alum...

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Oxygen Reduction Activity of Vapor-Grown Platinum Nanotubes

Cited by 28 publications

References 21 publications

Enhanced Oxygen Reduction Activity on Pt/C for Nafion-free, Thin, Uniform Films in Rotating Disk Electrode Studies

Enhanced Oxygen Reduction Activity on Pt/C for Nafion-free, Thin, Uniform Films in Rotating Disk Electrode Studies

Vapor Synthesis and Thermal Modification of Supportless Platinum–Ruthenium Nanotubes and Application as Methanol Electrooxidation Catalysts

Fabrication of anodic porous alumina via anodizing in cyclic oxocarbon acids

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