Realization of Rhodium Metal‐Oxide Electrode in Indifferent Electrolytes

Juodkazytė, Jurga; Juodkazis, Kȩstutis

doi:10.1002/elan.200302989

Cited by 4 publications

(3 citation statements)

References 25 publications

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“…However, contrary to sulfuric acid solution, an overall increase in iridium electrode mass was observed in the course of the first four potential cycles, whereas the subsequent cycling led to mass decrease. 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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“…On the basis of morphological evolution and electrochemical studies, we also illustrate a tentative growth mechanism for their structural evolution through microgalvanic cell formation. These Rh nanostructures are of potential relevance to many applications such as single electron devices, fuel cell electrocatalysis, , photoelectrochemical cells, and catalysis of a variety of organic reactions , (hydrogenation, hydroformylation, and hydride transformation, etc.) as demonstrated by their enhanced electrocatalytic properties toward formaldehyde oxidation.…”

Section: Discussionmentioning

confidence: 99%

Preparation and Characterization of Rhodium Nanostructures through the Evolution of Microgalvanic Cells and Their Enhanced Electrocatalytic Activity for Formaldehyde Oxidation

2009

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Shape-controlled morphological evolution of nanostructured Rh has been demonstrated with the help of a galvanic displacement reaction using Al in 1 mM aqueous Rh(III) chloride at an open circuit potential 0.99 V and at a temperature of 273 K (room temperature). Nanospheres composed of small nanoparticles of size around 2.9 ± 0.4 nm having uniform distribution with a FCC pattern have been evolved during the course of the reaction. Electrochemical results coupled with structural and morphological characterization data from transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and cyclic voltammetry (CV) suggested the formation of Rh nanostructures. Considering the role of the potential of substrate Al and Rh and diffusion of reactant and product species toward and from the surface of the Al, we proposed the tentative mechanism for the formation of microgalvanic cell. Significantly, these rhodium nanostructures exhibit enhanced electrocatalytic activity toward many fuel cell reactions as demonstrated by formaldehyde oxidation in 0.5 M NaOH. The present strategy is expected to be valid for preparing many other similar electrocatalysts (Pt, Au, and Pd) capable of exhibiting such a remarkable size- and shape-dependent reactivity.

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“…An anodic peak at around 1.4 V (vs. RHE) of Rh(nP)/nC LSV polarization curve might be attributed to an oxidation process of Rh 3+ to Rh 4+ before oxygen evolution. 41 Meanwhile, the electrochemical surface areas (ECSAs) were measured by means of CV in 0.1 M KOH solution as shown in Fig. S9.…”

Section: Resultsmentioning

confidence: 99%