Surface oxides on platinum at higher anodic potentials in sulphuric acid solutions

Balej, J.; Špalek, Otomar

doi:10.1135/cccc19720499

Cited by 55 publications

(12 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Under these conditions an oxide multilayer on the electrode surface is apparently formed. The structure of the multilayer was interpreted in terms of two distinguishable types of oxides (OxI and OxlI) [18,19,26,28]. The characteristic of the electrochemical reduction of the thick oxide layers has also been investigated under different experimental conditions including the influence of anions [32,33].…”

Section: Introductionmentioning

confidence: 99%

Changes in the electrochemical response of noble metals produced by square-wave potential perturbations

Chialvo

Triaca

Arvía

1983

Journal of Electroanalytical Chemistry and Interfacial Electroc

144

View full text Add to dashboard Cite

A square-wave potentaat anodizing procedure to obtain noble metal surfaces with both a controlled roughness and a reproducable electrochemacal response is presented. The influence of the charactenstacs of the square-wave potentaal perturbauon are systematxcally stu&ed. The mo&ficataon of the surface takes place through the formation of a hydrated platinum oxade layer wluch is later electroreduced. The mechamsm of growth of the hydrated oxide layer under both square-wave potentml perturbation and potentaostatac conditions ~s critically &scussed m terms of a complex sandwich-type structure.

show abstract

Section: Introductionmentioning

confidence: 99%

Changes in the electrochemical response of noble metals produced by square-wave potential perturbations

Chialvo

Triaca

Arvía

1983

Journal of Electroanalytical Chemistry and Interfacial Electroc

144

View full text Add to dashboard Cite

show abstract

“…According to the literature (14)(15)(16), there are at least two kinds of surface Pt sites for the adsorption of hydrogen on Pt. Evidence for the existence of more than one kind of surface Pt site for the adsorption of oxygen has been presented recently (17)(18)(19)(20)(21). We associate the two peaks in Fig.…”

Section: Discussionmentioning

confidence: 87%

On the Differential Thermal Analysis of the Platinum‐Oxygen System

Hoare

Paluch

Meibuhr

1976

J. Electrochem. Soc.

View full text Add to dashboard Cite

Differential thermal analyses (DTA) curves were obtained on preanodized and HNOs-passivated platinum (Pt) samples. In both cases two kinds of adsorption states for oxygen on Pt were detected as well as oxygen dissolved in the interior of the Pt metal. The DTA results agree well with the cathodic stripping pulse data obtained earlier.From x-ray diffraction analysis and vacuum fusion studies on samples of bright Pt passivated in air-saturated concentrated HNO3, it was concluded (1) that the Pt metal contained enough dissolved oxygen to be considered a Pt-O alloy. It was also found that oxygen could be made to diffuse through a thin Pt foil (2) under conditions of strong anodic polarization (6 mA/ cm ~ at 2V) of the back side of the Pt diaphragm in solutions of H2804 and that this anodization process can cause relatively large quantities of oxygen to be dissolved in the Pt lattice (3,4). In these studies three kinds of sorbed oxygen were distinguished: surface adsorbed oxygen, dermasorbed oxygen dissolved in the first two or three metallic layers, and absorbed oxygen dissolved in the bulk of the metal. The properties of Pt-O alloys made by passivation in HNO3 were somewhat different from those made by anodization (3, 5, 6). The HNQ-passivated Pt is much more stable than the Pt-O alloy obtained from anodization (6).Babenkova et al. (7) investigated the forms of hydrogen sorbed by palladium by measuring the desorption of hydrogen during a linearly programmed temperature rise experiment. They were able to find two forms of adsorbed hydrogen on the surface as well as the hydrogen dissolved in the bulk Pd.It seemed likely that a differential thermal analysis (DTA) of the platinum-oxygen system might enable one to observe the various forms of oxygen sorbed by Pt as well as to shed light on possible differences in the structure of Pt-O alloy formed by HNO3 passivation or by anodization.This report describes some DTA experiments made on Pt-O alloys. ExperimentalAll DTA curves were obtained with a furnace platform assembly with which analyses may be made on the sample in any controlled atmosphere at pressures ranging from 1.3 • 10 -6 to 2 atm. The reference sample was A1203 which is thermally inert in the temperature range of the scan, 0-1000~ The Pt-O alloy samples were made from small beads (0.11 cm in diameter) melted at the end of a Pt(99.99% pure) wire. These beads were cleaned by repeatedly heating to white heat in a H2 jet followed by quenching in concentrated HNO3. Afterward, three beads were mounted in a Teflon cell filled with concentrated HNO~ (70%) to soak for periods of time greater than 72 hr (6). Another set of three Pt beads were mounted in a Teflon cell filled with 2N H2SO4 solution and were anodized at 6 mA/cm 2 (2.00 • 0.05V) against a Pt gauze counterelectrode for periods of time greater than 24 hr. All Pt-O alloy samples were made at room temperature (24 ~ • 1~After formation of the Pt-O alloy, a bead was cut off of the wire and weighed ,-~37 mg) in a small Pt dish of * Electrochemical Society Active Mem...

show abstract

“…Rhodium, Rh, like other noble metals, forms surface oxides upon anodic polarization even in the region of water stability, thus below the thermodynamic reversible potential of the oxygen evolution reaction, E^ = 1.23 V, SHE (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20). In aqueous H 2 S0 4 solution, the oxide growth on Rh commences at 0.55 V, RHE (reversible hydrogen electrode), and up to ca.…”

mentioning

confidence: 99%

“…In the case of electroformation of oxides, the extend of surface oxidation depends on the nature of the metals, the polarization conditions (polarization potential, current density or time, E p , i p and t p , respectively) and the electrolyte composition and pH (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20). The oxide formed on an electrode surface markedly affects anodic Faradaic electrode processes at the double-layer by: (i) afFecting the reaction energetics; (ii) changing electronic properties of the metal electrode; (iii) imposing a barrier to the charge transfer; (iv) affecting the adsorption properties of the reaction intermediates and products (14)(15)(16)(17).…”

mentioning

confidence: 99%

Temperature Dependence of Growth of Surface Oxide Films on Rhodium Electrodes

Villiard

Jerkiewicz

1997

ACS Symposium Series

View full text Add to dashboard Cite

Surface oxides on Rh electrodes were formed by anodic polarization at potentials, E p , between 0.70 and 1.40 V, RHE, with an interval of 0.05 V for polarization times, t p , up to 10 000 s and at temperatures, T, between 278 and 348 K. This procedure results in thin films having their charge density, q ox , of less than 1260 μC cm -2 , thus their thickness, X, of up to 2 ML of Rh(OH) 3 . Cyclic-voltammetry, CV, reveals one states, OC1, in the oxide reduction profiles. Increase of Τ leads to augmentation of the oxide thickness but it does not influence its surface state; thermodynamics of their reduction are not affected by Τ variation. Plots of q ox versus log t p or 1 / q ox versus log t p for a wide range of Τ and E p allow one to discriminate between the logarithmic and the inverse-logarithmic oxide growth kinetics. Two kinetic regions are observed in the oxide formation plots, each one giving rise to a distinct growth mechanism. Oxides having X ≤ 1 ML of RhOH are formed according to the logarithmic kinetics and the process is limited by the rate of the place exchange between the Rh surface atoms and the electroadsorbed OH groups. Formation of oxides having X between 1 ML of RhOH and 2 ML of Rh(OH) 3 follows the inverse-logarithmic kinetics and the process is limited by the rate of escape of Rh 3+ from the metal into the oxide. Theoretical treatment of the data in the region corresponding to X > 1 ML of RhOH leads to determination of the potential drop across the film and the electric field within the oxide layer, the latter being of 10 9 V m -1 .Surface oxide films on various transition metals can be formed by application of electrochemical techniques or by exposure to an oxidizing atmosphere and the extent of surface oxidation, thus the oxide thickness, is affected by the oxidation conditions.

show abstract

Surface oxides on platinum at higher anodic potentials in sulphuric acid solutions

Cited by 55 publications

References 0 publications

Changes in the electrochemical response of noble metals produced by square-wave potential perturbations

Changes in the electrochemical response of noble metals produced by square-wave potential perturbations

On the Differential Thermal Analysis of the Platinum‐Oxygen System

Temperature Dependence of Growth of Surface Oxide Films on Rhodium Electrodes

Contact Info

Product

Resources

About