Interactions of adsorbed organic layers with hydrogen atoms on platinum electrodes

The adsorptive properties of platinized electrodes, as indicated by cyclic voltammetry, depended on the potential of platinum electrodeposition. Electrodes deposited above 0.05 V v. reversible hydrogen electrode were similar to smooth platinum, while those deposited at negative potentials showed anomalous behaviour, particularly with regard to hydrogen sorption. Measurements with such electrodes over a range of sweep rates showed slow sorption of about two hydrogen atoms in excess of the usual fast adsorption of one hydrogen atom per surface platinum atom. Freshly electrodeposited platinum had a specific activity for methanol oxidation of one-quarter to one-half that of smooth platinum. The lower activity was attributed to the effects of disordered surface structure and/or small particle size. Anodic-cathodic cycling produced surface recrystallization and activities close to that for smooth platinum.

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Organic layers via aryl diazonium electrochemistry: towards modifying platinum electrodes for interference free glucose biosensors

Electrochimica Acta ◽

10.1016/j.electacta.2016.04.145 ◽

2016 ◽

Vol 206 ◽

pp. 226-237 ◽

Cited By ~ 17

Author(s):

Matei D. Raicopol ◽

Corina Andronescu ◽

Ruxandra Atasiei ◽

Anamaria Hanganu ◽

Eugeniu Vasile ◽

...

Keyword(s):

Platinum Electrodes ◽

Glucose Biosensors ◽

Organic Layers ◽

Free Glucose

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SOME ABNORMAL HYDROGEN ELECTRODE REACTIONS

Canadian Journal of Chemistry ◽

10.1139/v59-028 ◽

1959 ◽

Vol 37 (1) ◽

pp. 213-221 ◽

Cited By ~ 17

Author(s):

D. J. G. Ives

Keyword(s):

Current Flow ◽

Reducing Power ◽

Open Circuit ◽

Theoretical Treatment ◽

Platinum Electrodes ◽

Thermal Deactivation ◽

Reaction Step ◽

Hydrogen Atoms ◽

Hydrogen Electrode ◽

Hydrogen Overpotential

A brief account is given of experiments in which gold electrodes, as a result of thermal deactivation in hydrogen, change from a state in which their behavior in relation to the hydrogen evolution reaction is normal to a state characterized by high positive rest potentials, greatly enhanced overpotentials which increase progressively during current flow, and which decay slowly on open circuit, generating potential–time curves which resemble desorption isotherms.Conclusions based on these phenomena are supported by the results of experiments with poisoned platinum electrodes, which not only behave similarly but are also shown to retain reducing power for a limited time on open circuit.It is suggested that electrodeposited hydrogen atoms may sometimes evaporate from an electrode into solution by a mechanism involving the participation of molecule-ions. A recent theoretical treatment of hydrogen overpotential can be extended to allow for the occurrence of such a final reaction step.

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Remarks on the diffuse interstellar lines

Symposium - International Astronomical Union ◽

10.1017/s0074180900100750 ◽

1967 ◽

Vol 31 ◽

pp. 91-93 ◽

Cited By ~ 4

Author(s):

G. Herzberg

Keyword(s):

Hydrogen Atoms ◽

Interstellar Gas

It is suggested that the diffuse interstellar lines are produced in the interstellar gas by molecules consisting of a few hydrogen atoms and one other atom, such as CH4+ or NH4. Diffuseness of the lines is assumed to result from predissociation of these molecules.

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Control of Metal Alloy Oxidation with Electric Fields

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100071260 ◽

1973 ◽

Vol 31 ◽

pp. 164-165

Author(s):

R. R. Dils ◽

P. S. Follansbee

Keyword(s):

Electric Fields ◽

Oxidation Process ◽

Base Alloy ◽

Oxide Surface ◽

Platinum Electrodes ◽

Insulating Layer ◽

Iron Base Alloy ◽

Alloy Oxidation ◽

Aluminum Oxide Layer ◽

And Control

Electric fields have been applied across oxides growing on a high temperature alloy and control of the oxidation of the material has been demonstrated. At present, three-fold increases in the oxidation rate have been measured in accelerating fields and the oxidation process has been completely stopped in a retarding field.The experiments have been conducted with an iron-base alloy, Pe 25Cr 5A1 0.1Y, although, in principle, any alloy capable of forming an adherent aluminum oxide layer during oxidation can be used. A specimen is polished and oxidized to produce a thin, uniform insulating layer on one surface. Three platinum electrodes are sputtered on the oxide surface and the specimen is reoxidized.

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Cerebral Tissue Response in Chronic Electrode Implantation

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100080547 ◽

1977 ◽

Vol 35 ◽

pp. 624-625

Author(s):

R.F. Dodson ◽

L.W-F Chu ◽

N. Ishihara

Keyword(s):

Tissue Response ◽

Whole Body ◽

Platinum Electrodes ◽

Fixed Tissue ◽

Electrode Implantation ◽

Surface Areas ◽

Tissue Changes ◽

Micron Diameter ◽

Extent Of Damage ◽

Electrode Sheath

The extent of damage surrounding an implanted electrode in the cerebral cortex is a question of significant importance with regard to attaining consistency and validity of physiological recordings. In order to determine the extent of such tissue changes, 150 micron diameter platinum electrodes were implanted in the cortex of four adult baboons, and after eight days the animals were sacrificed by whole body perfusion with a 3% glutaraldehyde in 0.1M phosphate fixative.The calvarium was carefully removed and the electrode tracts were readily discernible in the firm, glutaraldehyde fixed tissue.Careful dissection of the zone of the electrode tract resulted in a small block which was further sectioned into tip, mid-tract and surface areas. Ultrastructurally, damage extended from the electrode sheath to the greatest extent of from 0.2 to 3.5 mm.

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Use of fractals to describe microstructures of porous thick-film platinum electrodes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100121971 ◽

1992 ◽

Vol 50 (1) ◽

pp. 314-315

Author(s):

Steven D. Toteda

Keyword(s):

Fractal Dimension ◽

Power Plants ◽

Electrical Response ◽

Cubic Phase ◽

Platinum Electrodes ◽

Fine Grained ◽

Impedance Response ◽

Platinum Particles ◽

Energy Surfaces ◽

Highly Porous

Zirconia oxygen sensors, in such applications as power plants and automobiles, generally utilize platinum electrodes for the catalytic reaction of dissociating O2 at the surface. The microstructure of the platinum electrode defines the resulting electrical response. The electrode must be porous enough to allow the oxygen to reach the zirconia surface while still remaining electrically continuous. At low sintering temperatures, the platinum is highly porous and fine grained. The platinum particles sinter together as the firing temperatures are increased. As the sintering temperatures are raised even further, the surface of the platinum begins to facet with lower energy surfaces. These microstructural changes can be seen in Figures 1 and 2, but the goal of the work is to characterize the microstructure by its fractal dimension and then relate the fractal dimension to the electrical response. The sensors were fabricated from zirconia powder stabilized in the cubic phase with 8 mol% percent yttria. Each substrate was sintered for 14 hours at 1200°C. The resulting zirconia pellets, 13mm in diameter and 2mm in thickness, were roughly 97 to 98 percent of theoretical density. The Engelhard #6082 platinum paste was applied to the zirconia disks after they were mechanically polished ( diamond). The electrodes were then sintered at temperatures ranging from 600°C to 1000°C. Each sensor was tested to determine the impedance response from 1Hz to 5,000Hz. These frequencies correspond to the electrode at the test temperature of 600°C.

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A TEM study of the interface between organic matrix and aragonite in a biological hard tissue, nacre

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100129759 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1024-1025

Author(s):

Jun Liu ◽

Katie E. Gunnison ◽

Mehmet Sarikaya ◽

Ilhan A. Aksay

Keyword(s):

Mechanical Properties ◽

Ion Beam ◽

Laminated Composite ◽

Organic Matrix ◽

Pearl Oyster ◽

Interfacial Structure ◽

Interfacial Region ◽

Thin Sections ◽

Organic Layers ◽

Transmission Electron

The interfacial structure between the organic and inorganic phases in biological hard tissues plays an important role in controlling the growth and the mechanical properties of these materials. The objective of this work was to investigate these interfaces in nacre by transmission electron microscopy. The nacreous section of several different seashells -- abalone, pearl oyster, and nautilus -- were studied. Nacre is a laminated composite material consisting of CaCO3 platelets (constituting > 90 vol.% of the overall composite) separated by a thin organic matrix. Nacre is of interest to biomimetics because of its highly ordered structure and a good combination of mechanical properties. In this study, electron transparent thin sections were prepared by a low-temperature ion-beam milling procedure and by ultramicrotomy. To reveal structures in the organic layers as well as in the interfacial region, samples were further subjected to chemical fixation and labeling, or chemical etching. All experiments were performed with a Philips 430T TEM/STEM at 300 keV with a liquid Nitrogen sample holder.

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