Potential of a Platinum Electrode at Low Partial Pressures of Hydrogen or Oxygen

Warner, Theodore B.; Schuldiner, Sigmund

doi:10.1149/1.2423710

Cited by 37 publications

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“…As the redox concentration increases, the contribution of the redox half reactions increases and eventually dominates over the background half reactions. As far as we are aware, the only previous study that has observed a concentration dependent deviation from Nernstian behavior for molecules involves an inner-sphere electron transfer reaction, such as O 2 and H 2 …”

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confidence: 99%

“…As far as we are aware, the only previous study that has observed a concentration dependent deviation from Nernstian behavior for molecules involves an inner-sphere electron transfer reaction, such as O 2 and H 2 . 13 ■ EXPERIMENTAL SECTION Electrode Fabrication. The electrodes used in this study were constructed by sealing either a 25 μm Pt wire (Alfa Aesar, 99.95% purity) into a borosilicate glass capillary (0.75 mm inner diameter and 1.5 mm outer diameter, Sutter Instrument) under vacuum.…”

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confidence: 99%

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Ultra-Sensitive Potentiometric Measurements of Dilute Redox Molecule Solutions and Determination of Sensitivity Factors at Platinum Ultramicroelectrodes

Percival

Bard

2017

Anal. Chem.

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Open circuit potential (OCP) measurements can be very sensitive to small changes in the electrode environment and may allow detection of electron transfer events involving few, and maybe single, electrons. Factors affecting the overall sensitivity of OCP measurements were investigated to achieve the highest sensitivity. The OCP of platinum ultramicroelectrodes (UMEs) was determined in solutions that initially contained only supporting electrolyte where the OCP is a mixed potential governed by background faradaic processes. Then, increasing amounts of a redox couple at equimolar amounts of oxidized and reduced forms were added. In dilute solutions of the redox couple, the OCP deviates from the redox potential because of additional background half reactions occurring at the electrode. These dominate the OCP through their partial current contributions, shifting the OCP to a mixed potential region. The OCP at a platinum UME remains unchanged from the aqueous electrolyte solution mixed potential until ∼10 to 10 M concentrations of redox molecules are reached. At higher concentrations, the OCP moves toward the formal potential of the redox couple and eventually becomes poised at this value. By using a simple surface modification, the sensitivity to changing concentrations can be increased by almost 2 orders of magnitude. Numerical calculations with a Butler-Volmer formalism can estimate the contribution to the OCP mixed potential from background half reaction currents which are used to extract sensitivity factors from the change in potential with respect to current. The relative sensitivity to changing concentrations is shown to increase as the electrode size decreases.

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Ultra-Sensitive Potentiometric Measurements of Dilute Redox Molecule Solutions and Determination of Sensitivity Factors at Platinum Ultramicroelectrodes

Percival

Bard

2017

Anal. Chem.

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“…Dependence of currentless (stationary) potential of oxygen electrode on oxygen pressure (see (13)) was observed in solutions of various electrolytes: KOH [31], H 2 SO 4 [30,31,48], and HClO 4 [28,29]. This experimental fact indicates a single-electron character of reaction which defines the nature of currentless potential of platinum oxygen electrode.…”

Section: Discussion Of Orr Redox Cycle On Pt-electrodesmentioning

confidence: 99%

Oxygen-Containing Nanoclusters on the Surface of Pt-Electrodes and Oxygen Reduction Reaction in Alkaline Medium

Trunov

2018

International Journal of Electrochemistry

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Analysis of the role of oxygen-containing nanoclusters in oxygen reduction reaction (ORR) on Pt-electrodes in alkaline media is provided on the basis of the concept of electrochemical processes with slowed stage of consecutive heterogeneous chemical reaction (ConHCR). Under the ConHCR concept, the main factor determining the ORR characteristics is energetic inhomogeneity of electrode surface (EIES) according to Temkin. A new concept, according to which EIES is determined by the Gibbs energy of formation of oxygen-containing surface structures with inclusions of surface defects of the platinum crystal structure, s,d Pt, is formulated. A correlation between the level of EIES of Pt-electrodes and packing density of s,d Pt atoms on the surface of Pt(hkl) monocrystals is determined. The concept, according to which the stationary potential of ORR process is considered as a "mixed potential" of two reactions (electrochemical reduction of surface atom

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“…From repeated cathodic stripping determinations (3), the equivalent of about 3 or 4 monolayers of sorbed oxygen were detected. Rapid dissolution of oxygen in Pt was reported by Schuldiner and Warner (5), but this oxygen penetrated no further into the Pt surface than the first 2 or 3 atomic layers (5,6). The term "dermasorption" was suggested (5,6) to describe this form of occluded oxygen and to distinguish it from oxygen (known as absorbed oxygen) which had penetrated deeper into the metal lattice.…”

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confidence: 97%

On Dissolved Oxygen in Bulk Platinum

Hoare

1969

J. Electrochem. Soc.

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The hydrogen overvoltage was determined on the front side of a bright Pt foil in 2N H2SO4 solution while the solution on the back side was stirred with H2, N2, or 02. No change in the ~ was detected when the foil was connected as a diaphragm and when H2 stirring was replaced with 02 stirring on the back side. With the foil connected as a bielectrode, the ~ increased after an induction period depending on the thickness of the .foil when H2 stirring was" replaced with 02 stirring on the back side. These results indicate that under anodic polarization, oxygen can be dissolved in Pt. The dissolved oxygen can penetrate to the front side of the Pt foil where its presence as dermasorbed oxygen modified the catalytic activity of the Pt surface for the H2 evolution reaction. In the absence of anodization, oxygen sorbed from solution can penetrate the Pt lattice no further than the dermasorbed region.

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Potential of a Platinum Electrode at Low Partial Pressures of Hydrogen or Oxygen

Cited by 37 publications

References 0 publications

Ultra-Sensitive Potentiometric Measurements of Dilute Redox Molecule Solutions and Determination of Sensitivity Factors at Platinum Ultramicroelectrodes

Ultra-Sensitive Potentiometric Measurements of Dilute Redox Molecule Solutions and Determination of Sensitivity Factors at Platinum Ultramicroelectrodes

Oxygen-Containing Nanoclusters on the Surface of Pt-Electrodes and Oxygen Reduction Reaction in Alkaline Medium

On Dissolved Oxygen in Bulk Platinum

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