Electrochemical dissolution of metals of the platinum group by alternating current

Styrkas, A. D.; Styrkas, D. A.

doi:10.1007/bf00260693

Cited by 11 publications

(10 citation statements)

References 3 publications

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“…Such behavior of Ir electrode in acid and alkaline solutions could be understood presuming that a layer of slightly soluble hydrous iridium oxides [8] is formed/reduced during the anodic/ [23,24,28,29]. Styrkas et al [30] have demonstrated that platinum group metals can be dissolved in acid solutions using an alternating current.…”

Section: Resultsmentioning

confidence: 99%

EQCM Study of Iridium Anodic Oxidation in H₂SO₄ and KOH Solutions

et al. 2005

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In the present study anodic oxidation of iridium layer formed thermally on a gold-sputtered quartz crystal electrode has been investigated by electrochemical quartz crystal microgravimetry (EQCM) in the solutions of 0.5 M H 2 SO 4 and 0.1 M KOH. The emphasis here has been put on the microgravimetric behavior of iridium as a metal, because a few previous EQCM studies reported in literature have been devoted to iridium oxide films (IROFs). The objective pursued here has been to elucidate the nature of the main voltammetric peaks, which occur at different ranges of potential in the solutions investigated. It has been found that anodic oxidation of iridium electrode in 0.5 M H 2 SO 4 and 0.1 M KOH solutions is accompanied by irregular fluctuations of the electrode mass at 0.4 V < E < 0.8 V followed by regular increase in mass at 0.8 V < E < 1.2 V. The cathodic process initially, at 1.2 V > E > 0.9 V, proceeds without any or with slight increase in electrode mass, whereas at E < 0.8 V a regular decrease in mass is observed. It has been found that mass to charge ratio characterizing the processes of interest is 2 to 3 g F À1 in acidic medium, whereas in the case of alkaline one it is 4 to 6 g F À1. The main pair of peaks seen in the voltammograms of Ir electrode in alkaline medium at E < 0.8 V is attributable to redox transition Ir(0) ! Ir(III), whereas those observed in the case of acidic medium at E > 0.8 V should be related to the redox process Ir(0) ! Ir(IV) going via intermediate stage of Ir(III) formation. As a consequence of these redox transitions, the gel-like surface layer consisting of Ir(III) or Ir(IV) hydrous oxides forms on the electrode surface.

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Section: Resultsmentioning

confidence: 99%

EQCM Study of Iridium Anodic Oxidation in H₂SO₄ and KOH Solutions

et al. 2005

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“…After chronoamperometry test, TEM image and EDS maps show Rh H‐NSs completely maintain their hollow structures and chemical compositions (Figures S17 and S18, Supporting Information), indicating Rh H‐NSs are stable under long time running. On the one hand, Rh has high chemical inertness, resulting in excellent resistant to extremely harsh conditions . On the other hand, 3D interconnected structure of Rh H‐NSs can inhibit the Ostwald ripening phenomenon.…”

Section: Resultsmentioning

confidence: 99%

“…On the one hand, Rh has high chemical inertness, resulting in excellent resistant to extremely harsh conditions. [19,20] On the other hand, 3D interconnected structure of Rh H-NSs can inhibit the Ostwald ripening phenomenon. [13a,35] Thus, the high chemical inertness and particular 3D structures endow Rh H-NSs with excellent self-stability, which contributes the high stability of Rh H-NSs for the MOR.…”

Section: Stability Tests Of Rh H-nssmentioning

confidence: 99%

“…Besides, the strong oxidation property of aqua regia can dissolve the many other noble metal catalysts such as Pd and Ni, etc. However, Rh cannot be dissolved in aqua regia either at room temperature or even at 300 °C, implying that Rh nanostructures are resistant to extremely harsh conditions. Besides, it is note that Rh is stable in alkaline media at high voltage even 1.6 V versus RHE running for several hours .…”

Section: Introductionmentioning

confidence: 99%

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Selective Etching Induced Synthesis of Hollow Rh Nanospheres Electrocatalyst for Alcohol Oxidation Reactions

Kang

Xue

Zhao

et al. 2018

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The hollow noble metal nanostructures have attracted wide attention in catalysis/electrocatalysis. Here a two-step procedure for constructing hollow Rh nanospheres (Rh H-NSs) with clean surface is described. By selectively removing the surfactant and Au core of Au-core@Rh-shell nanostructures (Au@Rh NSs), the surface-cleaned Rh H-NSs are obtained, which contain abundant porous channels and large specific surface area. The as-prepared Rh H-NSs exhibit enhanced inherent activity for the methanol oxidation reaction (MOR) compared to state-of-the-art Pt nanoparticles in alkaline media. Further electrochemical experiments show that Rh H-NSs also have high activity for the electrooxidation of formaldehyde and formate (intermediate species in the course of the MOR) in alkaline media. Unfortunately, Rh H-NSs have low electrocatalytic activity for the ethanol and 1-propanol oxidation reactions in alkaline media. All electrochemical results indicate that the order of electrocatalytic activity of Rh H-NSs for alcohol oxidation reaction is methanol (C ) > ethanol (C ) > 1-propanol (C ). This work highlights the synthesis route of Rh hollow nanostructures, and indicates the promising application of Rh nanostructures in alkaline direct methanol fuel cells.

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“…In the first case, very harsh chemical or electrochemical conditions are typically applied,3b, 6b, 8 and all of the components of the electrode are dissolved or oxidized together with the platinum. For instance, for electrochemical dissolution processes, potential differences as high as 8 V are applied,9 or currents as high as 5 A cm −2 are used at temperatures in the range 50–100 °C 6a. For chemical dissolution processes, extremely corrosive liquids such as aqua regia are used 3a.…”

Section: Introductionmentioning

confidence: 99%

Environmentally Friendly Carbon‐Preserving Recovery of Noble Metals From Supported Fuel Cell Catalysts

2015

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The dissolution of noble-metal catalysts under mild and carbon-preserving conditions offers the possibility of in situ regeneration of the catalyst nanoparticles in fuel cells or other applications. Here, we report on the complete dissolution of the fuel cell catalyst, platinum nanoparticles, under very mild conditions at room temperature in 0.1 M HClO4 and 0.1 M HCl by electrochemical potential cycling between 0.5-1.1 V at a scan rate of 50 mV s(-1) . Dissolution rates as high as 22.5 μg cm(-2) per cycle were achieved, which ensured a relatively short dissolution timescale of 3-5 h for a Pt loading of 0.35 mg cm(-2) on carbon. The influence of chloride ions and oxygen in the electrolyte on the dissolution was investigated, and a dissolution mechanism is proposed on the basis of the experimental observations and available literature results. During the dissolution process, the corrosion of the carbon support was minimal, as observed by X-ray photoelectron spectroscopy (XPS).

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Electrochemical dissolution of metals of the platinum group by alternating current

Cited by 11 publications

References 3 publications

EQCM Study of Iridium Anodic Oxidation in H₂SO₄ and KOH Solutions

EQCM Study of Iridium Anodic Oxidation in H₂SO₄ and KOH Solutions

Selective Etching Induced Synthesis of Hollow Rh Nanospheres Electrocatalyst for Alcohol Oxidation Reactions

Environmentally Friendly Carbon‐Preserving Recovery of Noble Metals From Supported Fuel Cell Catalysts

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Electrochemical dissolution of metals of the platinum group by alternating current

Cited by 11 publications

References 3 publications

EQCM Study of Iridium Anodic Oxidation in H2SO4 and KOH Solutions

EQCM Study of Iridium Anodic Oxidation in H2SO4 and KOH Solutions

Selective Etching Induced Synthesis of Hollow Rh Nanospheres Electrocatalyst for Alcohol Oxidation Reactions

Environmentally Friendly Carbon‐Preserving Recovery of Noble Metals From Supported Fuel Cell Catalysts

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EQCM Study of Iridium Anodic Oxidation in H₂SO₄ and KOH Solutions

EQCM Study of Iridium Anodic Oxidation in H₂SO₄ and KOH Solutions