Multi-electron transfer processes

Among the double pulse techniques, DDPV is very attractive for the characterization of multi-electron transfer processes. Besides the reduction of undesirable effects, this technique gives well-resolved peak-shaped signals which are much more advantageous for the elucidation of these processes than the sigmoidal voltammograms obtained in Normal Pulse Voltammetry and discussed in Sect. 3.3. 

A. Molina, C. Serna, Q. Li, E. Laborda, C. Batchelor-McAuley, and R. G. Compton. Analytical solutions for the study of multi-electron transfer processes by staircase, cyclic and differential voltammetries at disc microelectrodes, J. Phys. Chem. C 116, 11470-11479 (2012). 

Commonly, only one electron is transferred between electrode and reactant. However, multi-electron transfer processes are of considerable interest due to their importance in catalytic processes such as those associated with the reduction of... 

On the other hand, the two sides of the same crystal of SrTiOs have been used for building a water splitting system that evolves H2 and O2 in separate compartments and avoids recombination. Thus irradiation of Au nanoparticles loaded SrTiOs causes electron transfer to the titanate conduction band. The trapped holes cause hydro q l oxidation in a multi electron transfer process, while the electrons reduce protons at the platinum surface adhering to the back side of the titanate ciystal. ... 

Skourtis, S. S. Beratan, D. N. Single- and Multi-electron Transfer Processes. In Principles and Theories-, Piotrowiak, P.,... 

This is another specific type of following reaction where the initial reaction product reacts chemically to yield a species O, which is itself at least as readily reduced as O. This type of reaction sequence is fairly common in multi-electron transfer processes in organic electrochemistry. It was discussed in some detail in an earlier chapter (Chapter 2) on pulse techniques, and the possibility of competing disproportionation reactions was considered. We will only consider here the case where homogeneous electron transfer can be ignored, the electron transfer are reversible, and the chemical reaction is irreversible. Other cases are discussed in the literature [7, 9-11]. 

Nitrate electroreduction has been extensively studied over the last few decades. This reactitMi is a multi-electron transfer process showing different mechanisms as a function of pH, nitrate and supporting electrolyte concentration, chemical composition and structure of the catalyst. In recent years, nitrate electroreduction has been widely studied over diamond and many monometallic electrodes such as Pb, Ni, Zn or Rh, Ru, Ir, Pd, Cu, Ag and Au. Because none of the common pure metals is able to provide high selectivities for nitrogen, bimetallic alloys or monometals modified with foreign metal adatoms were prepared and evaluated for the reduction of nitrate. More recently, an electrochemical process in which nitrate ions are reduced to ammonia at the cathode, and where the produced ammonia is oxidized at the anode to nitrogen with the contribution of hypochlorite ions, has been evaluated. 

Scheme 9.22 Multi-electron transfer processes facilitated by mixed-valence dirhodium complexes of the type Rh2° "(tfepma)2(L)2Cl2. Photocatalytic cycles for (a) Oj reduction, L = CN Bu, and (b) production,...

The use of solid photomaterials has been investigated since the 1980s using semiconductors as light absorbers and catalysts in several solvent media. The key issue in this case is that the band gap of the semiconductor used as photomaterials must match the potential of CO2 reduction. Figure 8.10 shows the band gap expressed in V of several semiconductors compared with the reduction potential of CO2 in one- and multi-electron transfer processes. 

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