Rhodium deposits on pyrolytic graphite substrate: Physico-chemical properties and electrocatalytic activity towards nitrate reduction in neutral medium

We study the physico-chemical properties and electrocatalytic activity towards oxygen reduction of two Fe–N–C catalysts based on carbide derived carbon.

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Electrocatalytic hydrogen evolution on the noble metal-free MoS2/carbon nanotube heterostructure: a theoretical study

Scientific Reports ◽

10.1038/s41598-021-83562-w ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Farhad Keivanimehr ◽

Sajjad Habibzadeh ◽

Alireza Baghban ◽

Amin Esmaeili ◽

Ahmad Mohaddespour ◽

...

Keyword(s):

Hydrogen Evolution ◽

Noble Metal ◽

Electrocatalytic Activity ◽

Density Functional ◽

Minimum Energy ◽

Chemical Properties ◽

Binding Energies ◽

Functional Theory ◽

Metal Free ◽

Physico Chemical

AbstractMolybdenum disulfide (MoS2) is considered as a promising noble-metal-free electrocatalyst for the Hydrogen Evolution Reaction (HER). However, to effectively employ such material in the HER process, the corresponding electrocatalytic activity should be comparable or even higher than that of Pt-based materials. Thus, efforts in structural design of MoS2 electrocatalyst should be taken to enhance the respective physico-chemical properties, particularly, the electronic properties. Indeed, no report has yet appeared about the possibility of an HER electrocatalytic association between the MoS2 and carbon nanotubes (CNT). Hence, this paper investigates the synergistic electrocatalytic activity of MoS2/ CNT heterostructure for HER by Density Functional Theory simulations. The characteristics of the heterostructure, including density of states, binding energies, charge transfer, bandgap structure and minimum-energy path for the HER process were discussed. It was found that regardless of its configuration, CNT is bound to MoS2 with an atomic interlayer gap of 3.37 Å and binding energy of 0.467 eV per carbon atom, suggesting a weak interaction between CNT and MoS2. In addition, the energy barrier of HER process was calculated lower in MoS2/CNT, 0.024 eV, than in the MoS2 monolayer, 0.067 eV. Thus, the study elaborately predicts that the proposed heterostructure improves the intrinsic electrocatalytic activity of MoS2.

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Modified lead dioxide for organic wastewater treatment: Physicochemical properties and electrocatalytic activity

Journal of the Serbian Chemical Society ◽

10.2298/jsc180712091s ◽

2019 ◽

Vol 84 (2) ◽

pp. 187-198 ◽

Cited By ~ 3

Author(s):

Olesia Shmychkova ◽

Tatiana Luk’yanenko ◽

Larisa Dmirtikova ◽

Alexander Velichenko

Keyword(s):

Wastewater Treatment ◽

Physicochemical Properties ◽

Electrochemical Oxidation ◽

Oxygen Evolution ◽

Electrocatalytic Activity ◽

Lead Dioxide ◽

Chemical Properties ◽

Destruction Rate ◽

Physico Chemical ◽

Pbo2 Anode

An investigation is reported on lead dioxide electrodeposition from methanesulfonate electrolytes additionally containing Ni2+ ions. It is shown that lead dioxide electrodes micromodified by nickel have different physico-chemical properties vs. nonmodified PbO2-anodes that are formed during the deposition. Electrocatalytical reactivity of electrodes involved in comparison to both the oxygen evolution, as well as to the electrooxidation of 2,4- dichlorophenoxyacetic (2,4-D) acid is investigated. Processes of electrochemical oxidation of 2,4-D on various materials occur qualitatively with the same mechanism and differ only in the rate. It is shown that the Ni-PbO2-anode possesses the highest electrocatalytic activity: the destruction rate of 2,4-D on it increases in 1.5 times in comparison with nonmodified lead dioxide. The COD of a 0.4 mM solution of 2,4-D, determined by the dichromate method, is 90.0 mg dm-3 which is 94 % of the theoretical value.

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COMPARATIVE CHARACTERISTICS OF PHYSICO-CHEMICAL PROPERTIES OF DRUGS TOPICAL APPLICATION FOR THE PREVENTION OF COMPLICATIONS OF TOOTH EXTRACTION

The actual problems in dentistry ◽

10.18481/2077-7566-2018-14-4-64-70 ◽

2018 ◽

Vol 14 (4) ◽

pp. 64-70

Author(s):

Ирина Костина ◽

Irina Kostina ◽

Вера Молвинских ◽

Vera Molvinskikh ◽

Надежда Белоконова ◽

...

Keyword(s):

Tooth Extraction ◽

Chemical Properties ◽

Iodine Content ◽

Iodine Concentration ◽

Bound State ◽

Collagen Sponge ◽

Model Systems ◽

Neutral Medium ◽

Duration Of Action ◽

Physico Chemical

Background. A comparative study of the dynamics of iodine desorption from drugs containing iodoform and used after tooth extraction to preserve blood clots and prevention, treatment of inflammatory complications. This took into account the type and form of drugs. The content and desorption of iodine determine the duration of local exposure to the drug on the tissues of the tooth well. Objectives. To study the physico-chemical properties of iodoform containing topical preparations for the prevention and treatment of alveolitis of the jaw. Methods. The objects of the study were complex multicomponent preparations of domestic production, presented in the dental market in the form of gauze bandage, collagen sponge, paste, powder containing iodoform. A standard titrimetric method was used to quantify the iodine content in aqueous systems. For the analysis of changes of iodine content in aqueous model systems applied to the spectrophotometric method in which the concentration of a substance was assessed according to the calibration chart from 0 minutes to 48 hours. In the model solution, the albumin and pH were changed, iodine concentration was determined in 1, 15 and 30 min. Results. Medications significantly differed in both the number of iodoform and desorption in the aquatic environment of the iodine. However, the content of iodoform in the preparations did not exceed the maximum permissible concentration. Desorption of iodine from the bandage after 15 minutes is significantly less than from the viscose flagellum. Desorption of iodine from the collagen sponge remains constant for 24 hours., but increases after 48 hours. Desorption of iodine from the powder is reduced after 45 minutes. Desorption of iodine from the paste gradually increases, reaches a maximum of 105 minutes and persists after 48 hours. In the albumin-bound state, iodine is more easily desorbed in an acidic medium, and at low concentrations of iodine, desorption in a neutral medium is significantly less. Conclusions. The duration of action of iodoform when applied topically affect the dosage form of the carrier (fiber, sponge, paste, powder), the concentration of the drug, the pH and albumin content in the aqueous medium.

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Decoration of specific sites on freeze-fractured membranes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100081565 ◽

1978 ◽

Vol 36 (2) ◽

pp. 140-141

Author(s):

H. Gross ◽

H. Moor

Keyword(s):

Pure Water ◽

Freeze Fracture ◽

Chemical Properties ◽

Surface Forces ◽

Sulfate Pentahydrate ◽

Copper Sulfate Pentahydrate ◽

Physico Chemical ◽

Water Of Hydration ◽

Small Container ◽

Binding Forces

Fracturing under ultrahigh vacuum (UHV, p ≤ 10-9 Torr) produces membrane fracture faces devoid of contamination. Such clean surfaces are a prerequisite foe studies of interactions between condensing molecules is possible and surface forces are unequally distributed, the condensate will accumulate at places with high binding forces; crystallites will arise which may be useful a probes for surface sites with specific physico-chemical properties. Specific “decoration” with crystallites can be achieved nby exposing membrane fracture faces to water vopour. A device was developed which enables the production of pure water vapour and the controlled variation of its partial pressure in an UHV freeze-fracture apparatus (Fig.1a). Under vaccum (≤ 10-3 Torr), small container filled with copper-sulfate-pentahydrate is heated with a heating coil, with the temperature controlled by means of a thermocouple. The water of hydration thereby released enters a storage vessel.

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Thin Pyrolytic Graphite Films for Electron Microscope Substrates

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100065183 ◽

1971 ◽

Vol 29 ◽

pp. 226-227 ◽

Cited By ~ 1

Author(s):

George H. N. Riddle ◽

Benjamin M. Siegel

Keyword(s):

Vacuum Chamber ◽

Pyrolytic Graphite ◽

High Vacuum ◽

Dark Field ◽

Ultra High Vacuum ◽

Graphite Substrate ◽

Nickel Substrate ◽

Routine Procedure ◽

Field Electron Microscopy ◽

Dark Field Electron

A routine procedure for growing very thin graphite substrate films has been developed. The films are grown pyrolytically in an ultra-high vacuum chamber by exposing (111) epitaxial nickel films to carbon monoxide gas. The nickel serves as a catalyst for the disproportionation of CO through the reaction 2C0 → C + CO2. The nickel catalyst is prepared by evaporation onto artificial mica at 400°C and annealing for 1/2 hour at 600°C in vacuum. Exposure of the annealed nickel to 1 torr CO for 3 hours at 500°C results in the growth of very thin continuous graphite films. The graphite is stripped from its nickel substrate in acid and mounted on holey formvar support films for use as specimen substrates.The graphite films, self-supporting over formvar holes up to five microns in diameter, have been studied by bright and dark field electron microscopy, by electron diffraction, and have been shadowed to reveal their topography and thickness. The films consist of individual crystallites typically a micron across with their basal planes parallel to the surface but oriented in different, apparently random directions about the normal to the basal plane.

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PHYSICO CHEMICAL PROPERTIES OF NICKEL OXIDE AT HIGH TEMPERATURE

Le Journal de Physique Colloques ◽

10.1051/jphyscol:1976798 ◽

1976 ◽

Vol 37 (C7) ◽

pp. C7-438-C7-442 ◽

Cited By ~ 2

Author(s):

R. FARHI ◽

G. PETOT-ERVAS

Keyword(s):

High Temperature ◽

Nickel Oxide ◽

Chemical Properties ◽

Physico Chemical

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Physico-Chemical Properties of Recombinant Desulphatohirudin

Thrombosis and Haemostasis ◽

10.1055/s-0038-1645073 ◽

1990 ◽

Vol 63 (03) ◽

pp. 499-504 ◽

Cited By ~ 4

Author(s):

A Electricwala ◽

L Irons ◽

R Wait ◽

R J G Carr ◽

R J Ling ◽

...

Keyword(s):

Molecular Weight ◽

Gel Filtration ◽

Chemical Properties ◽

Alpha Helix ◽

Apparent Molecular Weight ◽

Correlation Spectroscopy ◽

Nmr Studies ◽

Recombinant Hirudin ◽

Physico Chemical ◽

Recombinant Molecule

SummaryPhysico-chemical properties of recombinant desulphatohirudin expressed in yeast (CIBA GEIGY code No. CGP 39393) were reinvestigated. As previously reported for natural hirudin, the recombinant molecule exhibited abnormal behaviour by gel filtration with an apparent molecular weight greater than that based on the primary structure. However, molecular weight estimation by SDS gel electrophoresis, FAB-mass spectrometry and Photon Correlation Spectroscopy were in agreement with the theoretical molecular weight, with little suggestion of dimer or aggregate formation. Circular dichroism studies of the recombinant molecule show similar spectra at different pH values but are markedly different from that reported by Konno et al. (13) for a natural hirudin-variant. Our CD studies indicate the presence of about 60% beta sheet and the absence of alpha helix in the secondary structure of recombinant hirudin, in agreement with the conformation determined by NMR studies (17)

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