Electron Transfer at Liquid/Liquid Interfaces. The Effects of Ionic Adsorption, Electrolyte Concentration, and Spacer Length on the Reaction Rate

2002 ◽  
Vol 106 (15) ◽  
pp. 3933-3940 ◽  
Author(s):  
Biao Liu ◽  
Michael V. Mirkin
Keyword(s):  
Electron Transfer ◽  
Reaction Rate ◽  
Electrolyte Concentration ◽  
Liquid Interfaces ◽  
Spacer Length ◽  
Ionic Adsorption

Chemical Transformation of Fe, Air & Water to Ammonia: Variation of Reaction Rate with Temperature, Pressure, Alkalinity and Iron

2018 ◽  
Author(s):  
Ping Peng ◽  
Fang-Fang Li ◽  
Xinye Liu ◽  
Jiawen Ren ◽  
jessica stuart ◽  
...  
Keyword(s):  
Particle Size ◽  
Reaction Rate ◽  
Electrolyte Concentration ◽  
Iron Concentration ◽  
Reaction Medium ◽  
Iron Particle ◽  
Intermediate Step ◽  
Ammonia Production ◽  
Pure Nitrogen ◽  
Alkaline Reaction

The rate of ammonia production by the <u>chemical </u>oxidation of iron, N<sub>2</sub>(from air or as pure nitrogen) and water is studied as a function of (1) iron particle size, (2) iron concentration, (3) temperature, (4) pressureand (5) concentration of the alkaline reaction medium. The reaction meduium consists of an aqueous solution of equal molal concentrations of NaOH and KOH (Na<sub>0.5</sub>K<sub>0.5</sub>OH). We had previously reported on the <u>chemical </u>reaction of iron and nitrogen in alkaline medium to ammonia as an intermediate step in the <u>electrochemical </u>synthesis of ammonia by a nano-sized iron oxide electrocatlyst. Here, the intermediate <u>chemical </u>reaction step is exclusively explored. The ammonia production rate increases with temperature (from 20 to 250°C), pressure (from 1 atm to 15 atm of air or N<sub>2</sub>), and exhibits a maximum rate at an electrolyte concentration of 8 molal Na<sub>0,5</sub>K<sub>0,5</sub>OH in a sealed N<sub>2</sub>reactor. 1-3 µm particle size Fe drive the highest observed ammonia production reaction rate. The Fe mass normalized rate of ammonia production increases with decreasing added mass of the Fe reactant reaching a maximum observed rate of 2.2x10<sup>-4</sup>mole of NH<sub>3</sub>h<sup>-1</sup>g<sup>-1</sup>for the reaction of 0.1 g of 1-3 µm Fe in 200°C 8 molal Na<sub>0.5</sub>K<sub>0.5</sub>OH at 15 atm. Under these conditions 5.1 wt% of the iron reacts to form NH<sub>3</sub>via the reaction N<sub>2</sub>+ 2Fe + 3H<sub>2</sub>O ®2NH<sub>3</sub>+ Fe<sub>2</sub>O<sub>3</sub>.

The dehydrogenation of 1,4-dihydronaphthalene by tetrachloro-p-benzoquinone

1976 ◽  
Vol 54 (14) ◽  
pp. 2261-2265 ◽  
Author(s):  
Z. M. Hashish ◽  
I. M. Hoodless
Keyword(s):  
Electron Transfer ◽  
Charge Transfer ◽  
Reaction Rate ◽  
Second Order ◽  
Charge Transfer Complexes ◽  
Ion Transfer ◽  
Hydride Ion ◽  
Rate Determining Step ◽  
Hydride Ion Transfer

The dehydrogenation of 1,4-dihydronaphthalene by tetrachloro-p-benzoquinone in phenetole solution has been investigated. The present work does not fully confirm earlier studies which report that the reaction follows second-order kinetics and that the hydride ion transfer is rate determining. In the investigations described in this paper second-order kinetics are only observed in the later stages of the reaction and a 1:1 stoichiometry of the reactants in the process is not obtained. Substitution of tritium in the 1,4-positions of the hydrocarbon appears to not significantly affect the reaction rate. The present results indicate that charge-transfer complexes are formed in the reaction and it is suggested that electron transfer within these complexes could be the rate-determining step in the dehydrogenation.

Concerted double proton-transfer electron-transfer between catechol and superoxide radical anion

2017 ◽  
Vol 19 (38) ◽  
pp. 26179-26190 ◽  
Author(s):  
Jorge Quintero-Saumeth ◽  
David A. Rincón ◽  
Markus Doerr ◽  
Martha C. Daza
Keyword(s):  
Electron Transfer ◽  
Proton Transfer ◽  
Superoxide Anion ◽  
Radical Anion ◽  
Reaction Rate ◽  
Superoxide Radical ◽  
Superoxide Radical Anion ◽  
Double Proton Transfer

Catechol reacts with a superoxide anion via concerted double proton-transfer electron-transfer with a reaction rate that is dominated by tunneling.

Volumes of activation for electrode processes of various charge-types in nonaqueous solvents

2001 ◽  
Vol 79 (12) ◽  
pp. 1864-1869 ◽  
Author(s):  
Mitsuru Matsumoto ◽  
Delanie Lamprecht ◽  
Michael R North ◽  
Thomas W Swaddle
Keyword(s):  
Electron Transfer ◽  
Reaction Rate ◽  
Electrode Reaction ◽  
State Theory ◽  
Exchange Reactions ◽  
Pt Electrode ◽  
Electrode Processes ◽  
Solvent Dynamics ◽  
The Mean ◽  
Dynamical Control

Volumes of activation (ΔV‡el) are reported for electron transfer at a Pt electrode of Mn(CN-cyclo-C6H11)62+/+ in acetonitrile, acetone, methanol, and propylene carbonate, and of Fe(phen)33+/2+ in acetonitrile. In all cases, ΔV‡el is markedly positive, whereas for the homogeneous self-exchange reactions of these couples in the same solvents the corresponding parameter is known to be strongly negative. The rate constants for the electrode reactions correlate loosely with the mean reactant diffusion coefficients (i.e., with solvent fluidity) and the ΔV‡el values with the volumes of activation for diffusion (i.e., for viscous flow), consistent with solvent dynamical control of the electrode reaction rate in organic solvents. A detailed analysis of ΔV‡el values of the kind presented for a couple with an uncharged member (Zhou and Swaddle, Can. J. Chem. 79, 841 (2001)) fails, however, either because of ion-pairing effects with these more highly charged couples or because of breakdown of transition-state theory in predicting the contribution of the activational barrier. Attempts to measure ΔV‡el for the oxidation of the uncharged molecule ferrocene at various electrodes in acetonitrile were unsuccessful, although ΔV‡el was again seen to be clearly positive.Key words: electrode kinetics, volumes of activation, nonaqueous electron transfer, solvent dynamics.

scholarly journals Stochastic Analysis of Electron Transfer and Mass Transport in Confined Solid/Liquid Interfaces

Surfaces ◽  
2020 ◽  
Vol 3 (3) ◽  
pp. 392-407
Author(s):  
Marco Favaro
Keyword(s):  
Electron Transfer ◽  
Photoelectron Spectroscopy ◽  
Ambient Pressure ◽  
Chemical Properties ◽  
Liquid Films ◽  
Liquid Interfaces ◽  
Electrical Potentials ◽  
Voltammetric Behavior ◽  
Current Densities ◽  
Solid Liquid

Molecular-level understanding of electrified solid/liquid interfaces has recently been enabled thanks to the development of novel in situ/operando spectroscopic tools. Among those, ambient pressure photoelectron spectroscopy performed in the tender/hard X-ray region and coupled with the “dip and pull” method makes it possible to simultaneously interrogate the chemical composition of the interface and built-in electrical potentials. On the other hand, only thin liquid films (on the order of tens of nanometers at most) can be investigated, since the photo-emitted electrons must travel through the electrolyte layer to reach the photoelectron analyzer. Due to the challenging control and stability of nm-thick liquid films, a detailed experimental electrochemical investigation of such thin electrolyte layers is still lacking. This work therefore aims at characterizing the electrochemical behavior of solid/liquid interfaces when confined in nanometer-sized regions using a stochastic simulation approach. The investigation was performed by modeling (i) the electron transfer between a solid surface and a one-electron redox couple and (ii) its diffusion in solution. Our findings show that the well-known thin-layer voltammetry theory elaborated by Hubbard can be successfully applied to describe the voltammetric behavior of such nanometer-sized interfaces. We also provide an estimation of the current densities developed in these confined interfaces, resulting in values on the order of few hundreds of nA·cm−2. We believe that our results can contribute to the comprehension of the physical/chemical properties of nano-interfaces, thereby aiding to a better understanding of the capabilities and limitations of the “dip and pull” method.

Zur Theorie der Elektronenübergangsreaktionen in molekularen Komplexen / Theory of Electron Transfer Reactions in Molecular Complexes

1974 ◽  
Vol 29 (6) ◽  
pp. 880-887 ◽  
Author(s):  
P. P. Schmidt
Keyword(s):  
Activation Energy ◽  
Electron Transfer ◽  
Charge Transfer ◽  
Rate Constant ◽  
Reaction Rate ◽  
Charge Transfer Complex ◽  
Rate Theory ◽  
Transfer Step ◽  
Donor And Acceptor ◽  
Inner Sphere

This paper reports a theory of the inner sphere-type electron transfer reaction. Inner sphere reactions, as opposed to the outer sphere variety, require that the solvate or ligand shells surrounding the electron donor and acceptor species undergo considerable change in the course of the electron transfer. In this paper we assume that the electron transfer step takes place in a molecular complex which exists in equilibrium with the reactants. The electron transfer step occurs as a non-radiative charge transfer-type transition. In this manner we treat the charge transfer kinetics, in particular, the evaluation of the reaction rate constant, in the same manner as is usual for non-radiative problems. The analysis leading to the rate constant expression is based on Yamamoto’s general chemical reaction rate theory. The rate constant expressions obtained are quite general, they hold for any degree of strength of coupling between subsystems comprising the entire system. The activation energy, in the Arrhenius form for the rate constant, shows a dependence on the energy (work) of formation of the intermediate charge transfer complex, on vibrational shift energies associated with the molecular motions of the ligands, and on solvent repolarization energies. The activation energy also shows an important dependence on coupling terms which link the vibrations of the molecular inner shell with the polarization states of the (assumed) dielectric continuum which surrounds the charge transfer participants. The approach we take in developing this theory we believe points the way towards the development of a more complete theory capable of accounting for the dynamics of the molecular reorganization leading to the intermediate charge transfer complex as well as accounting for the electron transfer step itself.

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