Interfacial charge-transfer reactions

Interfacial Charge Transfer Reactions in Colloidal Dispersions and Their Application to Water Cleavage by Visible Light Gratzel, M. 15... 

In the absence of kinetic complications, the interfacial charge transfer reactions that occur during photoelectrolytic processes at illuminated semi-... 

Thus, the concentration of the diffusing species has the same value c at any t at f = 0 or for any r > 0 at x >. This is true for almost all electrochemical diffusion problems in which one switches on (at t = 0) the appropriate current or potential difference across the interface and thus sets up interfacial charge-transfer reactions which, by consuming or producing a species, provoke a diffusion flux of that species. 

From these modified forms of the Nernst-Planck flux equation (4.231), one can see that even if f,. - 0, it is still possible to have a flux of a species provided there is a concentration gradient, which is often brought into existence by interfacial charge-transfer reactions at the electrode-electrolyte interfaces consuming or generating the species. 

The effective valence for dissolution increases from a value of about 2 at low current density to a value of 4 in the electropolishing domain [59-63, 67-69], as shown in Fig. 10a [63] and Fig. 10b [67]. While gravimetric determinations may be subject to a number of errors derived from oxide formation and hydrogen adsorption, these data show that the dissolution process associated with pore formation, in the absence of illumination, proceeds through interfacial charge transfer reaction involving two... 

From thermodynamie and kinetic principles the interface between two immiscible liquids can have catalytic properties for interfacial charge-transfer reactions [1-10]. It is also possible to shift the redox potential scale in a desired direction by selecting appropriate solvents, thereby permitting reactions to occur that are highly unfavorable in a homogeneous phase [1,11-15]. The kinetic mechanism underlying the catalytic properties of the liquid/liquid interface was discussed first by Kharkats and Volkov [4-7] as they introduced a new term interfacial catalysis. ... 

Redox reactions at the interface between immiscible liquids fall into two classes. The first class includes spontaneous processes that occur in the absence of external electromagnetic fields [16-77]. This type of redox transformation has been investigated in bioenergetics, model membrane systems and at oil/water interfaces [78-99]. Redox reactions in the second class occur at the interface between immiscible electrolytes when external electrical fields are applied to the interface, and under these conditions interfacial charge-transfer reactions take place at controlled interfacial potentials [100-139]. 

Equation (35) is plotted in Figs 5 and 6, which show that the activation energy of the process decreases (or increases) greatly at low s. Accordingly, the rate constant of charge transfer across the interface increases (or decreases) sharply at relatively low sp. Figure 6 shows that the liquid-liquid interface has selective properties and can catalyze or inhibit interfacial charge-transfer reactions due to electrostatic effects. 

U. Kolle, J. Moser, M. Gratzel, Dynamics of interfacial charge-transfer reactions in semiconductor dispersions - reduction of cobaltoceniumdicarboxylate in colloidal Ti02, Inorg. Chem. 1985,24(14), 2253-2258. 

Long before interfacial charge transfer reactions began to be studied systematically. Bell [8] observed a multielectron transfer reaction across a benzene/water interface. This involved permanganate oxidation of benzoyl-o-tol-uidine to benzoylanthranilic acid ... 

Electrochemical reactions involve the transfer of electrons between an electronically conducting phase and localised energy levels on molecules or ions in an adjacent phase. In many cases, the reacting chemical species are present in an electrolyte solution, but interfacial charge transfer reactions can also involve solid ionic or covalent phases as well as ionic liquids (molten salts). Since the description of electron transfer should be applicable to a wide range of systems, it is useful to list some of the materials which can form part of the interface... 

---