Reactions involving H, OH and O species on rhodium in H2SO4·12H2O and HClO4·5.5H2O in the range 198–298 K

Florit, M.I.; Bolzán, Agustín Eduardo; Arvía, Alejandro Jorge

doi:10.1016/0022-0728(95)03983-n

Cited by 9 publications

(4 citation statements)

References 25 publications

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“…Moreover, there is a less defined double layer in the cathodic scan direction due to the apparent overlapping of the surface oxide reduction peaks and hydrogen adsorption. That coincides with the previously published CV results for polycrystalline Rh in a sulfuric acid solution [31][32][33]35,37]. Figure 1c shows the CVs of Rh(poly) in 0.1 M NaOH.…”

Section: Electrochemical Characterization Of Rh(poly) In Acid and Alk...supporting

confidence: 91%

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Study of Oxygen Reduction Reaction on Polycrystalline Rhodium in Acidic and Alkaline Media

Golubović,

Varničić,

Štrbac

2024

Catalysts

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This study examines the kinetics and mechanism of the oxygen reduction reaction (ORR) on a polycrystalline rhodium electrode (Rh(poly)) in acidic and alkaline media, using rotating disc electrode measurements. This study found that the ORR activity of the Rh(poly) electrode decreases in the order of 0.1 M NaOH > 0.1 M HClO4 > 0.05 M H2SO4 concerning the half-wave potentials. The Tafel slopes for ORR on Rh(poly) in the cathodic direction are 60 and 120 mV dec−1 at low and high overpotentials, respectively, in perchloric acid and alkaline solutions. However, strongly adsorbed sulfate anions hinder the ORR on Rh(poly) in sulfuric acid, leading to higher Tafel slopes. The highest ORR activity of Rh(poly) in an alkaline media suggests the promoting role of the specifically adsorbed OH− anions and RhOH. In all cases, ORR on Rh(poly) proceeds through the 4e-series reaction pathway.

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Section: Electrochemical Characterization Of Rh(poly) In Acid and Alk...supporting

confidence: 91%

“…Rh surface oxidation can also occur through other mechanisms, which include the formation of Rh 2 O, RhO, Rh 2 O 3, and RhO(OH) 3 species on the electrode surface [25,32,33].…”

Section: Electrochemical Characterization Of Rh(poly) In Acid and Alk...mentioning

confidence: 99%

Study of Oxygen Reduction Reaction on Polycrystalline Rhodium in Acidic and Alkaline Media

Golubović,

Varničić,

Štrbac

2024

Catalysts

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“…Cycle 2 represents formation and reduction of the surface layer of Rh(III) oxide. It should be noted, that the shape of voltammograms was identical to that known from the literature for polycrystalline rhodium [9,12] and was practically independent of the nature of supporting electrolyte. One can see that upon the reversal of the potential scan at ca.…”

Section: Resultsmentioning

confidence: 89%

Realization of Rhodium Metal‐Oxide Electrode in Indifferent Electrolytes

Juodkazytė¹,

Juodkazis²

2004

Electroanalysis

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The pH-dependence of the stationary open-circuit potential E i¼0 st of rhodium electrode with a surface layer of anodically formed insoluble compounds has been studied in sulfate and phosphate solutions by means of cyclic voltammetry and chronopotentiometry. The range of potentials of the investigations performed has been confined to the region of rhodium electrochemical oxidation/reduction, i.e., 0.2 < E < 1.2 V (RHE) in order to prevent any possible interference of other reactions such as H 2 and O 2 evolution. It has been shown that rhodium electrode with a layer of surface compounds formed anodically at E << 1.23 V (RHE) behaves like a reversible metal-oxide electrode within the range of pH values from ca. 1.0 to ca. 8.0. It has been presumed that the stationary potential of such electrode is determined by the equilibrium of the following electrochemical reaction:The pH-dependence of the reversible potential of E Rh/Rh(OH) 3 electrode has been found to be:In acid solutions (pH < 2.0) rhodium hydroxide dissolves into the electrolyte, therefore, to reach equilibrium, the solution must be saturated with Rh(OH) 3 . This has been achieved by adding Rh 3þ ions in the form of Rh 2 (SO 4 ) 3 . The solubility product of Rh(OH) 3 , estimated from the experimental E Rh/Rh(OH) 3 À pH dependence obtained, is ca. 1.0 Â 10 À48, which is close to the value given in literature.

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“…The inset of Figure shows this CV. The CV shows the typical surface features associated with a polycrystalline rhodium electrode . The hydrogen adsorption/desorption on rhodium was seen around −0.2 V as a reversible couple.…”

Section: Resultsmentioning

confidence: 99%

Electrocrystallization of Rhodium Clusters on Thiolate-Covered Polycrystalline Gold

et al. 2005

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This study reports on the electrochemical deposition of rhodium metal clusters on a polycrystalline gold electrode, modified with a monolayer of dodecanethiol through self-assembly from solution. The deposition process was investigated using cyclic voltammetry, chronoamperometry, and electrochemical quartz crystal microbalance. It is shown that the presence of the thiol monolayer drastically alters the nucleation and growth mechanism compared with the mechanism on the bare gold electrode. The small uncovered gold domains, located at the imperfections in the thiolate monolayer which are induced by the gold nanoroughness, act as nucleation sites for small rhodium clusters. At longer times, these clusters can outgrow the organic monolayer. The resulting surface morphology was characterized by scanning electron microscopy. Rhodium electrocrystallization on the bare gold substrate resulted in an ensemble of a very large amount of very small clusters that are difficult to distinguish from the gold roughness. In contrast, in the presence of a self-assembled monolayer (SAM) of dodecanethiol covalently attached to the gold electrode, the resulting deposit consisted of an ensemble of hemispherical particles. The size distribution of the rhodium particles obtained by using double step chronoamperometry was compared to the ones obtained with cyclic voltammetry and "classical" chronoamperometry. It is shown by X-ray photoelectron spectroscopy that the SAM is still present after rhodium deposition on the thiolate-covered gold substrate. Because the rhodium clusters are directly attached to the gold substrate and can thus easily be electrified, the resulting interface could be used as a composite electrode consisting of a random array of gold supported rhodium nano/microparticles separated from each other by an organic phase. On the other hand, it is shown that the SAM is easily removed by electrochemical oxidation without dissolving the rhodium clusters and, thus, leaving a different array of rhodium clusters on the gold surface compared with the topography obtained in the absence of the SAM. From this point of view, substrate modification with such "removable" organic monolayers was found to be an interesting tool to tune the nano- or microtopography of electrochemically deposited rhodium.

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Reactions involving H, OH and O species on rhodium in H2SO4·12H2O and HClO4·5.5H2O in the range 198–298 K

Cited by 9 publications

References 25 publications

Study of Oxygen Reduction Reaction on Polycrystalline Rhodium in Acidic and Alkaline Media

Study of Oxygen Reduction Reaction on Polycrystalline Rhodium in Acidic and Alkaline Media

Realization of Rhodium Metal‐Oxide Electrode in Indifferent Electrolytes

Electrocrystallization of Rhodium Clusters on Thiolate-Covered Polycrystalline Gold

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