Selective Dissolution of Pt&amp;ndash;Co Binary Alloys and Surface Enrichment of Platinum in Sulfuric Acid Solution

Ooi, Azusa; Hoshi, Yoshinao; Tada, Eiji; Nishikata, Atsushi

doi:10.2320/matertrans.m2014107

Cited by 9 publications

(14 citation statements)

References 34 publications

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“…Our group introduced inductively coupled plasma mass spectrometry (ICP-MS) to quantify the trivial amounts of dissolved Pt and M. 1519) PtM alloys were subjected to 100 cycles of potential cycling in a stationary solution, and the amount of dissolved Pt and M was directly quantified by analyzing the test solution using ICP-MS. Using this method, we clarified the effects of M species, 15) range of potential cycling, 16) Co composition on the dissolution mechanism of PtM alloys, 17,18) and the correlation between the dissolution of M and the morphological change of the surface. 19) However, the amount of dissolved Pt and M obtained by ICP-MS was an integrated value in the 100 cycles of potential cycling.…”

Section: Introductionmentioning

confidence: 99%

Time-Resolved Measurements of Dissolution Rates of Platinum and Palladium by a Solution Flow Cell Combined with ICP-MS

2021

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A time-resolved measurement system, which combined a commercially available solution-flow cell and an inductively coupled plasma mass spectrometer, was established for determining the dissolution rate of platinum (Pt) and palladium (Pd) in this study. The detection limit of the system was successfully improved by thinning the cell channel, and the limits for Pt and Pd were 0.13 pg cm ¹2 s ¹1 and 0.39 pg cm ¹2 s ¹1 , respectively. When the system was applied to Pt and Pd under potential cycling that mimicked the start/stop conditions of a polymer electrolyte fuel cells (PEFCs), it was revealed that the dissolution of Pt and Pd started from a more negative potential than that reported in previous studies. In addition, we succeeded in obtaining time-resolved measurements of the Pt and Pd dissolution rates below the open circuit potential of the PEFCs (approximately 1.0 V) and clarified that the dissolution mechanisms of Pt and Pd were different.

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Section: Introductionmentioning

confidence: 99%

Time-Resolved Measurements of Dissolution Rates of Platinum and Palladium by a Solution Flow Cell Combined with ICP-MS

2021

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“…Our previous work suggested the dissolution model of Co-rich Pt alloys; numerous cylindrical pits uniformly distributed on the surface as a result of Co selective dissolution and Pt surface diffusion (porous Pt-enriched layer formation). 19 However, no porous structure was detected because obtaining the porous surface morphology of Pt-Co alloys is not very straightforward. No highmagnification images of Pt-Co alloys using FE-SEM could be obtained because of the magnetic property of the Pt-Co alloys.…”

Section: Gbmentioning

confidence: 99%

“…We directly measured the amount of both Pt and M dissolved from Pt-M alloys in a test solution using inductively coupled plasma-mass spectrometer (ICP-MS) under 100 cycles of potential cycling; this method was applied to various alloys, such as Pt-cobalt (Co), Pt-nickel (Ni), Pt-iron (Fe), and Pt-Cu. [16][17][18][19][20] It was confirmed that both Pt and M are dissolved from Pt-M alloys and that the amount of the dissolution of M is much higher than that of Pt. Recently, a novel system combining ICP-MS with a solution-flow system has been successfully established for the online and simultaneous detection of both Pt and M. [21][22][23][24] We also established a solution-flow electrochemical technique, known as channel flow multielectrode (CFME), for the detection of both Pt and Fe.…”

mentioning

confidence: 90%

“…In our previous reports, 18,19 the amount of Co selectively dissolved from Pt-Co alloys and electrochemical active surface area (S ECSA ) were measured during long-term immersion tests. We proposed a growth model of pits resulting from the selective dissolution of Co. Based on the established model, we estimated the thickness of Pt-enriched layer and the radius of pits; however, the change in surface structure arising from the selective dissolution of Co has not been clarified.…”

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Dissolution and the Consequent Surface Enrichment of Platinum in Pt–Cu Binary Alloys under Potential Cycling

Ooi¹,

Tada²,

Nishikata³

2020

J. Electrochem. Soc.

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In this study, electrochemistry was combined with mass spectroscopy and surface analysis to investigate the selective dissolution of Cu and the consequent surface enrichment of Pt in Pt-Cu binary alloys. Two different compositions of Pt-50at% Cu (Pt-50Cu) and Pt-75at% Cu (Pt-75Cu) underwent potential cycling. Cu from both alloys was selectively dissolved, although trivial Pt dissolution occurred, causing the subsequent formation of a Pt-enriched layer on the alloys' surfaces. The morphology of the layer was quite different between the two alloys. The Pt-enriched layer formed on the Pt-50Cu surface was extremely thin and compact, further suppressing Cu dissolution from the alloy in the later stage of potential cycling. The Pt-enriched layer formed on the Pt-75Cu surface contained numerous pits, mainly because a lot of Cu was dissolved from Pt-75Cu during potential cycling. Thus, Cu continued to dissolve from the bottom of the pits at the later stage, causing the thickness of the Pt-enriched layer to gradually grow with an increase in the cycle number. The correlation between Pt and Cu dissolution and surface morphological changes of Pt-Cu alloys was discussed.

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“…1417) We have reported that both Pt and M dissolve from PtM alloys under potential cycling and that much more M dissolves than Pt. In other words, M was found to be selectively dissolved from PtM alloys, and the effects of the specific M used, 14) the potential range of the cycling, 15) and the alloy composition 16,17) on this selective dissolution behavior were investigated. Moreover, in order to clarify the dissolution behavior of PtM alloys in detail, a channel-flow multi-electrode (CFME) has been developed.…”

Section: Introductionmentioning

confidence: 99%

Identical-Location Scanning Electron Microscopy Observation of Surface Morphological Changes of Pt–Cu Nanoparticles

et al. 2020

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The surface morphological changes of electrodeposited Pt75 at% Cu (Pt75Cu) nanoparticles under potential cycling were investigated by identical-location scanning electron microscopy. The electrodeposited nanoparticles consisted of numerous nuclei (³3 nm in diameter) that agglomerated to form larger secondary particles (3050 nm). Upon immersion in sulfuric acid, Pt shells formed on the surfaces of the Pt75Cu nanoparticles due to the selective dissolution of Cu. Although around 40% of the Cu was dissolved from Pt75Cu, no noticeable surface morphological changes were observed. Thereafter, Pt75Cu was subjected to potential cycling between 0.05 and 1.0 V, whereupon surface smoothing of the nanoparticles due to the surface diffusion of Pt was observed. Conversely, when Pt75Cu was potential-cycled between 0.05 and 1.4 V, the particle diameters of the nanoparticles drastically decreased and the nuclei on the surface completely disappeared owing to Pt dissolution and re-deposition. The heat-treated nanoparticles developed numerous pores on their surfaces during immersion and the initial stage of potential cycling. However, their final morphologies were found to be similar to those of the non-heated sample. The formation of pores can be explained by the coarsening of nuclei by heat treatment.

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Selective Dissolution of Pt–Co Binary Alloys and Surface Enrichment of Platinum in Sulfuric Acid Solution

Cited by 9 publications

References 34 publications

Time-Resolved Measurements of Dissolution Rates of Platinum and Palladium by a Solution Flow Cell Combined with ICP-MS

Time-Resolved Measurements of Dissolution Rates of Platinum and Palladium by a Solution Flow Cell Combined with ICP-MS

Dissolution and the Consequent Surface Enrichment of Platinum in Pt–Cu Binary Alloys under Potential Cycling

Identical-Location Scanning Electron Microscopy Observation of Surface Morphological Changes of Pt–Cu Nanoparticles

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