Temperature dependence of the Tafel slope and electrochemical barrier symmetry factor,. beta. , in electrode kinetics

Journal Article · Fri Sep 01 00:00:00 EDT 1989 · Journal of the Electrochemical Society; (USA)

DOI:https://doi.org/10.1149/1.2097440· OSTI ID:7227371

Conway, B E ^[1]; Tessier, D F ^[2]; Wilkinson, D P ^[3]

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1. Dept. of Chemistry, Univ. of Ottawa, Ontario (CA)
2. Alcan International, Research Labs. Kingston, Ontario (CA)
3. Moli Energy Limited, Burnaby, Vancouver, British Columbia (CA)

The significance of the new-established situation that the Tafel slopes, b, ( = d{eta}/d In i) for simple charge-transfer processes at electrodes are usually not represented with respect to variation with temperature, T, by the conventional relation b = RT/{beta} cpF, where {beta} is a constant-valued electrochemical charge-transfer barrier-symmetry coefficient, is examined in the light of recent comments on the problem. Clear evidence is given that b has the form b = RT({beta}sub H + T{beta}{sub s})F for proton transfer at Hg in water and various other solvents, where {beta}{sub H} and T{beta}{sub s} are enthalpic components of the overall {beta}, corresponding to experimentally observable potential-dependence of both the enthalpy and the entropy of activation, respectively. The frequent deviation from conventional behavior thus arises because the entropy of activation, as well as the energy of activation, can be potential-dependent, a situation that, until recently, has been neglected in inter-pretations of electrode-kinetic experiments. The origin of the conventional effect of potential on electrode reaction rates, through the change of electrode work function,{Phi}, with overpotential or electrode potential, V, ({Phi}{sub v} = {Phi}{sub v = O}{plus minus} eV), is examined critically in relation to the potential-dependent surface-potential component, {chi}{sub d}, in {Phi}, which can also be T-dependent.

• OSTI ID: 7227371
• Journal Information: Journal of the Electrochemical Society; (USA), Vol. 136:9; ISSN 0013-4651
• Country of Publication: United States
• Language: English

Related Subjects

25 ENERGY STORAGE
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ELECTROCHEMISTRY
DIFFUSION BARRIERS
ACTIVATION ENERGY
CHARGE TRANSPORT
CHEMICAL REACTION KINETICS
ENTHALPY
ENTROPY
EXPERIMENTAL DATA
MERCURY
PROTONS
TEMPERATURE DEPENDENCE
WATER
BARYONS
CHEMISTRY
DATA
ELEMENTARY PARTICLES
ELEMENTS
ENERGY
FERMIONS
HADRONS
HYDROGEN COMPOUNDS
INFORMATION
KINETICS
METALS
NUCLEONS
NUMERICAL DATA
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
REACTION KINETICS
THERMODYNAMIC PROPERTIES
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400400 - Electrochemistry