Platinum Electro-dissolution in Acidic Media upon Potential Cycling

Xing, Liyan; Hossain, Mohammad A.; Tian, Min; Beauchemin, Diane; Adjemian, Kev; Jerkiewicz, Gregory

doi:10.1007/s12678-013-0167-9

Cited by 98 publications

(153 citation statements)

References 23 publications

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“…Thus, the transient, non-equilibrium process corresponding to peak A 1 was assigned to noble metal dissolution due to surface re-construction by interfacial place-exchange between the upper noble metal layer and adsorbed oxygenated species. 24,25,[64][65][66] The results shown in the current work are fully in line with the suggestion of the crucial role of place-exchange in the metal destabilization and eventual dissolution. The -0.059 V/pH shift in the oxide formation and correspondingly in the place-exchange commencement explains the approximate pH-independence of the dissolution onset of gold and platinum on the RHE scale.…”

Section: Noble-metal Dissolution During Oxide Formation and Reduction-supporting

confidence: 91%

“…However, it should be stressed that these oxides are not considered metastable, which would speak against the transient nature of dissolution. It is also unlikely that dissolution is due to a possible metastable state during the transition from AuO to Au 2 O 3 and PtO to PtO 2 , as the increase in oxidation state appears at more positive potential in comparison to the measured onset of dissolution, e.g as discussed for the case of platinum by Xing et al 24 Thus, we assume here that the metastable states are Au 2 O and Pt 2 O. Indeed, successful synthesis of aurous gold oxide was claimed in the nineteenth and early twentieth century, 80,83,88 although, a possibility of misinterpretation of the experimental results was discussed.…”

Section: Journal Of the Electrochemicalmentioning

confidence: 98%

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A Comparative Study on Gold and Platinum Dissolution in Acidic and Alkaline Media

Cherevko

Žeradjanin

Keeley

et al. 2014

J. Electrochem. Soc.

250

270

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Electrochemical dissolution of gold and platinum in 0.1 M HClO 4 , 0.1 M H 2 SO 4 , and 0.05 M NaOH is investigated. The qualitative picture of both metals' dissolution is pH-independent. Oxidation/reduction of the metal's surface leads to the transient dissolution peaks which we label A 1 and C 1 on the dissolution profiles. Commencement of the oxygen evolution reaction (OER) results in the additional dissolution peak A 2 . Quantitatively, there are important differences. The amount of gold transiently dissolved in alkaline medium is more than an order of magnitude higher in comparison to that in acidic medium. Oppositely, steady-state gold dissolution in base in the potential region of OER is hindered. The transient dissolution of platinum is by a factor of two higher in base. It is suggested that variation of the pH does not change the mechanism of the OER on platinum. Consequently, the dissolution rate of platinum is equal in acidic and alkaline electrolytes. As an explanation of the observed difference in gold dissolution, a difference in the thickness of compact oxide formed in acid and base is suggested. Growth of a thicker compact oxide in the alkaline medium explains the increased transient and the decreased steady-state dissolution of gold. Platinum and gold are perhaps the most frequently studied metals in electrochemistry. In particular, they constitute important model systems in the context of fundamental investigations of the mechanism and kinetics of the initial stages of metal oxidation. Surface processes during transition of adsorbed hydroxyl groups to, initially, compact couple of monolayers thickness and, later, relatively thick bulk phase oxides have occupied electrochemists for many decades. In the earliest works, investigations were directed toward the general problem of metal passivity, hotly debated at the beginning of the twentieth century. [1][2][3] In the 1960s and 1970s, the rapid development of fuel cells and application of platinum as a catalyst for the hydrogen oxidation and the oxygen reduction reactions (HOR and ORR) re-stimulated research efforts on noble metal oxidation. As adsorbed intermediates and other oxygenated species present on the catalyst surface were believed to have a poisoning effect on the rate of the ORR, understanding of the oxygen-platinum interaction was of substantial importance. The great progress in the development of electrochemical experimental techniques and surface analytics in these years significantly contributed to new insights of electrocatalysis at the solid-liquid interface. The understanding of noble metal oxidation is, however, not only crucial for these reactions but also the essential step in the comprehension of dissolution. Despite its importance in general and as a basis for the current work, the description of the theories and models for noble metal oxidation over the last century is beyond the scope of the present article. The interested reader is therefore referred to a comprehensive work published by Conway, and references therein. Plat...

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Section: Noble-metal Dissolution During Oxide Formation and Reduction-supporting

confidence: 91%

Section: Journal Of the Electrochemicalmentioning

confidence: 98%

A Comparative Study on Gold and Platinum Dissolution in Acidic and Alkaline Media

Cherevko

Žeradjanin

Keeley

et al. 2014

J. Electrochem. Soc.

250

270

View full text Add to dashboard Cite

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“…34 The β-oxide is envisioned to go below the surface Pt atoms due to placeexchange. [35][36][37][38] The position of this second peak shifts toward lower potentials with the number of consecutive TWs with decreased intensity. Additionally, the profile of the H ads features is altered with increased consecutive TWs region (ii).…”

Section: 29mentioning

confidence: 96%

Platinum Dissolution in Fuel Cell Electrodes: Enhanced Degradation from Surface Area Assessment in Automotive Accelerated Stress Tests

Rice

Urchaga

Pistono

et al. 2015

J. Electrochem. Soc.

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Automotive fuel cells are plagued by high platinum-based cathode catalyst costs exacerbated by high catalyst loadings to circumvent performance losses induced by typical urban drive cycles. Accelerated durability tests are commonly used to evaluate the impact of nano-structure and/or operating conditions on cathode catalyst loss rates. To map out loss rates the electrochemical surface area (ECSA) of the catalyst is periodically monitored. Herein the accelerated stress testing was performed 25,000 times by imposing perturbations from 0.9 V to 0.6 V in a triangular wave profile while the ECSA was measured by assessing the hydrogen adsorption/desorption region with a lower potential limit of 0.025 V at intermittent points during the triangular wave perturbations. The ECSA loss observed during the 25,000 triangle wave cycles is 7% when measured only 2 times, but 26.3% when measured 250 times. The exacerbated losses during frequent low potential ECSA measurements suggest a restructuring of the catalyst surface due to the formation of a protective β-oxide, as seen by alterations in the cyclic voltammtric profile and particle size distribution. The increasing price of fossil fuel stimulated by an impending near future accessible supply depletion combined with the increased awareness of the adverse contributions of the Internal Combustion Engines (ICEs) on global warming has driven an international research thrust toward alternative energy production for personal automotive transportation from alternative energy technologies. Proton Exchange Membrane Fuel Cells (PEMFCs) currently appear as one of the potential alternatives to ICEs for automotive applications due to their higher efficiency and the fact that they use hydrogen and air (21% oxygen) as fuel and oxidant, respectively, with water as the only by-product. Furthermore, depending on the production method, hydrogen can be considered as a renewable source of energy if generated in ways such as electrolysis from either wind turbines or solar energy.The commercialization and massive production of automotive PEMFC technologies is still a challenge due to durability and cost limitations.1 The PEMFC type is the most suitable fuel cell technology to replace ICEs for vehicle propulsion because of the solid electrolyte permitting comparable travel distances, available power for frequent fast idle-to-peak transients to support typically sized personal vehicles and fast startup/shutdown. However, the relatively low working temperature of PEMFCs (typically below 100• C, due to membrane limitations) requires the use of Pt based catalysts for both the anode and the cathode catalyst layers thereby significantly increasing their price. Utilization of finely dispersed catalyst nanoparticles onto a high surface electrically conducting substrates (typically high surface carbon supports) and optimization of catalytic layers have yet allowed a drastic decrease of the catalytic layer cost by lowering the Pt loading by a factor of 10 (reaching 0.4 mg. cm −2 total loading) in the past 30 ...

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“…The works of Topalov et al [10], Xing et al [21], as well as Rinaldo et al [22] revealed a staggering enhancement in Pt dissolution rate by a factor ∼2000 during voltage cycling in accelerated stress tests when the upper potential limit of the voltage cycle was increased above 1.2 V RHE . It was found consistently in these independent studies that the reduction of Pt oxide during the reduction part of the voltage cycle is responsible for the hugely increased rate of Pt dissolution.…”

Section: Introductionmentioning

confidence: 97%

Atomistic Mechanism of Pt Extraction at Oxidized Surfaces: Insights from DFT

Eslamibidgoli

Eikerling

2016

Electrocatalysis

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In this article, we propose a novel mechanism for the atomic-level processes that lead to oxide formation and eventually Pt dissolution at an oxidized Pt(111) surface. The mechanism involves a Pt extraction step followed by the substitution of chemisorbed oxygen to the subsurface. The energy diagrams of these processes have been generated using density functional theory and were analyzed to determine the critical coverages of chemisorbed oxygen for the Pt extraction and O ads substitution steps. The Pt extraction process depends on two essential conditions: (1) the local coordination of a Pt surface atom by three chemisorbed oxygen atoms at nearestneighboring fcc adsorption sites; (2) the interaction of the buckled Pt atom with surface water molecules. Results are discussed in terms of surface charging effects caused by oxygen coverage, surface strain effects, as well the contribution from electronic interaction effects. The utility of the proposed mechanism for the understanding of Pt stability at bimetallic surfaces will be demonstrated by evaluating the energy diagram of a Cu ML /Pt(111) near-surface alloy.

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Platinum Electro-dissolution in Acidic Media upon Potential Cycling

Cited by 98 publications

References 23 publications

A Comparative Study on Gold and Platinum Dissolution in Acidic and Alkaline Media

A Comparative Study on Gold and Platinum Dissolution in Acidic and Alkaline Media

Platinum Dissolution in Fuel Cell Electrodes: Enhanced Degradation from Surface Area Assessment in Automotive Accelerated Stress Tests

Atomistic Mechanism of Pt Extraction at Oxidized Surfaces: Insights from DFT

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