scholarly journals Single entity electrochemistry and the electron transfer kinetics of hydrazine oxidation

Nano Research ◽  
2021 ◽  
Author(s):  
Ruiyang Miao ◽  
Lidong Shao ◽  
Richard G. Compton
Keyword(s):  
Electron Transfer ◽  
Bulk Solution ◽  
Relative Contribution ◽  
Rate Determining Step ◽  
Multistep Process ◽  
Ph Range ◽  
Electro Catalytic Oxidation ◽  
Single Particle Impact ◽  
The Impact ◽  
Kinetics Of

AbstractThe mechanism and kinetics of the electro-catalytic oxidation of hydrazine by graphene oxide platelets randomly decorated with palladium nanoparticles are deduced using single particle impact electrochemical measurements in buffered aqueous solutions across the pH range 2–11. Both hydrazine, N2H4, and protonated hydrazine N2H5+ are shown to be electroactive following Butler-Volmer kinetics, of which the relative contribution is strongly pH-dependent. The negligible interconversion between N2H4 and N2H5+ due to the sufficiently short timescale of the impact voltammetry, allows the analysis of the two electron transfer rates from impact signals thus reflecting the composition of the bulk solution at the pH in question. In this way the rate determining step in the oxidation of each specie is deduced to be a one electron step in which no protons are released and so likely corresponds to the initial formation of a very short-lived radical cation either in solution or adsorbed on the platelet. Overall the work establishes a generic method for the elucidation of the rate determining electron transfer in a multistep process free from any complexity imposed by preceding or following chemical reactions which occur on the timescale of conventional voltammetry.

The Oxidation of Dithiocarbamate Anion by Substitution Inert Metal Complexes

1989 ◽  
Vol 42 (7) ◽  
pp. 1085 ◽  
Author(s):  
PJ Nichols ◽  
MW Grant
Keyword(s):  
Electron Transfer ◽  
Exchange Rate ◽  
Metal Complexes ◽  
Radical Anion ◽  
Outer Sphere ◽  
Aqueous Acetone ◽  
Kinetics Of Oxidation ◽  
Rate Determining Step ◽  
Exchange Rate Constant ◽  
Kinetics Of

The kinetics of oxidation of dithiocarbamate anions to thiuram disulfides in aqueous acetone by {Fe(CN)6}3- and 11 other substitution inert metal complexes have been investigated. Outer-sphere electron transfer, resulting in the formation of dithiocarbamate thio radicals, is the rate determining step. A Marcus cross reaction treatment allows an estimate for the redox potential for the dithiocarbamate radical/anion couple. For diethyldithiocarbamate, E �(edtc/edtc-) = 425 � 33 mV v.s.c.e. and the outer-sphere electron self-exchange rate constant is log kex = 7.0 � 0.3. A comparison with thiophenolate oxidation is also given.

Galvanostatic study of the kinetics of lithium deposition on platinum electrode in dimethylformamide

1991 ◽  
Vol 56 (1) ◽  
pp. 241-245
Author(s):  
Dafeng Xu ◽  
Shengmin Cai ◽  
Xizun Wu ◽  
Wenzhi Zhang
Keyword(s):  
Electron Transfer ◽  
Metal Surface ◽  
Platinum Electrode ◽  
Deposition Process ◽  
Constant Current ◽  
Rate Determining Step ◽  
Current Pulses ◽  
Lithium Deposition ◽  
Kinetics Of

The deposition of lithium in dimethylformamide (DMF) has been studied by means of galvanostatic measurements. The overpotential was recorded during constant current pulses of so short a duration that only a few monolayers per pulse were deposited. The experiments were carried out under conditions of minimum contamination of the metal surface. The deposition process of Li in DMF is irreversible, the electron transfer being the rate-determining step. A mechanism of Li electrodeposition in DMF was proposed.

Kinetics of the interactions between dyes and micelles

1986 ◽  
Vol 64 (5) ◽  
pp. 955-959 ◽  
Author(s):  
Vincent C. Reinsborough ◽  
Josef F. Holzwarth
Keyword(s):  
Hydrophobic Interactions ◽  
Sodium Dodecylsulfate ◽  
Bulk Solution ◽  
Sds Micelles ◽  
Ph Jump ◽  
Wide Ph Range ◽  
Ph Range ◽  
Rate Limiting ◽  
Kinetics Of ◽  
Continuous Flow Method

The rates of association of three azo dyes, methyl red (MR), methyl orange (MO), and pyridine-2-azo-p-dimethylaniline (PADA), with sodium dodecylsulfate (SDS) and cetyltrimethylammonium bromide (CTAB) micelles in water were measured at 25 °C over a wide pH range by the continuous flow method of integrating observation (CFMIO). The association was considered in 3 steps: bulk solution encounter, pH jump, and electrostatic and hydrophobic interactions. Either the first or third step is rate limiting depending on the charge of the dye. The rate constant of association of neutral PADA, MR, and MO with SDS micelles is approximately 2 × 106 dm3mol−1s−1 while charging the dyes positively increases k to 109 dm3mol−1 s−1. Increasing the hydrophobicity of dye or micelle increases k for the interaction with the neutral dye species. Changes in k with pH for the dye–CTAB association were less pronounced.

Kinetics of solvent extraction of metal ions with HEDHP. III. The kinetics and mechanism of solvent extraction of Cr(III) from acidic aqueous solutions with bis-(2-ethyl hexyl) phosphoric acid in benzene

1979 ◽  
Vol 57 (23) ◽  
pp. 3011-3016 ◽  
Author(s):  
Muhammad Fakhrul Islam ◽  
Ranjit Kumar Biswas
Keyword(s):  
Solvent Extraction ◽  
Phosphoric Acid ◽  
Aqueous Phase ◽  
Organic Phase ◽  
Forward Rate ◽  
Nitrate Ions ◽  
Rate Determining Step ◽  
Ethyl Hexyl ◽  
Ph Range ◽  
Kinetics Of

The rate of solvent extraction of chromium(III) from aqueous sulphuric acid solutions (containing 0.05 mol dm−3 sulphate ion and 0.25 mol dm−3 acetate buffer, ionic strength, I = 0.40 mol dm−3) with bis-(2-ethyl hexyl) phosphoric acid (HDEHP or H2A2) in benzene has been measured under various conditions. The rate of backward extraction measurement of Cr(III) from organic phase to aqueous phase is not possible due to the inert property of Cr(III)–DEHP chelate. The forward rate is found to be first-order w.r.t. Cr(III) concentration in the aqueous phase and HDEHP concentration in the organic phase. The order w.r.t. H+ concentration varies from −1 to 1 over the pH range 1.5 to 5.25. The rate is found to decrease with increasing sulphate and nitrate ions concentrations in the aqueous phase. At (30 ± 1) °C, the rate expression, in the presence of sulphate, acetate, and nitrate ions, is found to be represented by:[Formula: see text]In the absence of the anions, the formation of CrHA22+ intermediate complex (Cr(OH)2+ + H2A2(0) → CrHA22+ + H2O) is the rate determining step at all acidities. The effects of the anions on the rate are discussed.

scholarly journals The impact of surface coverage on the kinetics of electron transfer through redox monolayers on a silicon electrode surface

2015 ◽  
Vol 186 ◽  
pp. 216-222 ◽  
Author(s):  
Simone Ciampi ◽  
Moinul H. Choudhury ◽  
Shahrul Ainliah Binti Alang Ahmad ◽  
Nadim Darwish ◽  
Anton Le Brun ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Electrode Surface ◽  
Surface Coverage ◽  
The Impact ◽  
Kinetics Of

KINETICS OF THE OXIDATION OF MERCURY(I) BY THALLIUM (III) IN AQUEOUS SOLUTION

1957 ◽  
Vol 35 (9) ◽  
pp. 1020-1030 ◽  
Author(s):  
A. M. Armstrong ◽  
J. Halpern
Keyword(s):  
Electron Transfer ◽  
Mercury Atom ◽  
Perchloric Acid Solution ◽  
Transfer Processes ◽  
Rate Determining Step ◽  
Aqueous Perchloric Acid ◽  
The Right ◽  
Electron Transfer Processes ◽  
Kinetics Of ◽  
Hydrolysis Of

The kinetics of the oxidation of mercury(I) by thallium(III) in aqueous perchloric acid solution, i.e. Hg(I)2 + Tl(III) → 2Hg(II) + Tl(I), have been examined. The rate law was found to be of the form −d[Hg(I)2]/dt = kexp[Hg(I)2][Tl(III)]/[Hg(II)] where kexp is inversely dependent on the concentrations of H+ and of ClO4−. The rate-determining step of the reaction appears to be a 'two-electron transfer' between a mercury atom, formed by the dismutation of Hg2++, and a hydrolyzed thallium ion, i.e. Hg + TlOH++ → Hg++ + Tl+ + OH−. The rate constant, k, of this reaction is given by k = 1016±2 exp[−14000 ± 3000/RT] liters mole−1 sec.−1.H+ retards the reaction by opposing the hydrolysis of Tl+++, while the effect of ClO4− appears to be due to its complexing with Hg2++, Cl− and Br− catalyze the reaction probably by complexing with Hg++, thus displacing the Hg2++dismutation equilibrium, [Formula: see text], to the right and increasing the concentration of Hg atoms. The kinetics and mechanism of the Tl(I)–Tl(III) isotopic electron exchange reaction and of other electron transfer processes in solution are considered in the light of these observations.

Kinetic of oxidation of methyl orange by vanadium(V) under conditions VO2+ and decavanadates coexist: Catalysis by Triton X-100 micellar medium

2019 ◽  
Author(s):  
Chem Int
Keyword(s):  
Methyl Orange ◽  
Solution Ph ◽  
Vanadium Concentration ◽  
Limiting Behavior ◽  
First Order ◽  
First Order Kinetics ◽  
Ph Range ◽  
Kinetic Pattern ◽  
Triton X ◽  
Kinetics Of

The kinetics of oxidation of methyl orange by vanadium(V) {V(V)} has been investigated in the pH range 2.3-3.79. In this pH range V(V) exists both in the form of decavanadates and VO2+. The kinetic results are distinctly different from the results obtained for the same reaction in highly acidic solution (pH < 1) where V(V) exists only in the form of VO2+. The reaction obeys first order kinetics with respect to methyl orange but the rate has very little dependence on total vanadium concentration. The reaction is accelerated by H+ ion but the dependence of rate on [H+] is less than that corresponding to first order dependence. The equilibrium between decavanadates and VO2+ explains the different kinetic pattern observed in this pH range. The reaction is markedly accelerated by Triton X-100 micelles. The rate-[surfactant] profile shows a limiting behavior indicative of a unimolecular pathway in the micellar pseudophase.

Kinetics of carbon monoxide methanation on a Ni/SiO2 catalyst

1990 ◽  
Vol 55 (7) ◽  
pp. 1678-1685
Author(s):  
Vladimír Stuchlý ◽  
Karel Klusáček
Keyword(s):  
Carbon Monoxide ◽  
Reaction Rate ◽  
Catalyst Activity ◽  
Adsorbed Hydrogen ◽  
Reaction Products ◽  
Co Methanation ◽  
Molar Ratios ◽  
Rate Determining Step ◽  
Higher Temperature ◽  
Kinetics Of

Kinetics of CO methanation on a commercial Ni/SiO2 catalyst was evaluated at atmospheric pressure, between 528 and 550 K and for hydrogen to carbon monoxide molar ratios ranging from 3 : 1 to 200 : 1. The effect of reaction products on the reaction rate was also examined. Below 550 K, only methane was selectively formed. Above this temperature, the formation of carbon dioxide was also observed. The experimental data could be described by two modified Langmuir-Hinshelwood kinetic models, based on hydrogenation of surface CO by molecularly or by dissociatively adsorbed hydrogen in the rate-determining step. Water reversibly lowered catalyst activity and its effect was more pronounced at higher temperature.

Some Aspects of the Electroreduction of Niazid to Nicotinamide on Mercury Electrodes in Acidic Media

1992 ◽  
Vol 57 (9) ◽  
pp. 1836-1842 ◽  
Author(s):  
Rafael Marín Galvín ◽  
José Miguel Rodríguez Mellado
Keyword(s):  
Electron Transfer ◽  
Essential Role ◽  
Uv Spectroscopy ◽  
Acidic Media ◽  
Polarographic Wave ◽  
Rate Determining Step ◽  
Tafel Slopes ◽  
Reaction Orders ◽  
Mercury Electrodes ◽  
The Waves

The electroreduction of niazid on mercury electrodes has been studied in acidic media (pH < 6). Tafel slopes and reaction orders were obtained at potentials corresponding to the foot of the first polarographic wave. On the basis of both polarographic and voltammetric results it has been shown that the waves appearing at more negative potentials correspond to the reduction of nicotinamide. Protonation of niazid plays an essential role in its reduction and pK values of 1.4, 3.2 and 11.5 were obtained by UV spectroscopy. The process corresponding to the first wave is irreversible, being the second one-electron transfer the rate determining step. Above pH 4 the process is complex due to the overlapping of the waves caused by the occurrence of protonation reactions.

Sign in / Sign up

Export Citation Format

Share Document