H2O2 reduction

Despite the high catalytic activity toward H2O2 reduction and disproportionation, ORR catalysis does not appear to proceed via free H2O2 as inferred from... 

The low limit on the rate constant fehetero of 0-0 bond heterolysis in the putative ferric-hydroperoxo intermediate by analyzing the turnover frequency of H2O2 reduction at potentials 0.6-0.4 V (vs. NHE at pH 7). 

Loetzbeyer T, Schuhmann W, Schmidt H-L. 1995. Direct electrocatalytic H2O2 reduction with hemin covalently immobilized at a monolayer-modified gold electrode. J Electroanal Chem 395 341. 

To understand the effect of the protein on this modeled reaction mechanism, we selected the first reaction step, H2O2 reduction by a glutathione molecule for further investigations using the ONIOM (QM MM) method [28], The computational setup was similar to the structural study, but the effects of the additional water molecules were added from the active-site model. It is assumed that the reaction coordinate is the same as in the active-site study and no additional reaction pathways were investigated. An important point of the present ONIOM study is the full optimization of QM MM transition states using the novel ONIOM algorithms [9],... 

Catalases and peroxidases both promote H2O2 reduction by mechanisms that involve ferryl intermediates. Catalases differ from peroxidases by their ability to use H2O2 both as an electron acceptor and as donor, thus catalysing the disproportionation reaction (catalatic activity) (equation 1) ... 

P2Wi706iFe "(H20) H2O2 reduction Nitrite reduction Sulfate buffer (pH 3) Acetate buffer (pH 5) 94b... 

Fig. 32 Electrocatalysis of O2 and H2O2 reductions in the presence of 10 M CU4P4W30 in a pH 5 medium. The scan rate was 2 mV s, the working electrode was glassy carbon and the reference electrode was SCE. Eor more detailed information see text (taken from Ref 115).

CH3COOU -E CH3COOH) for O2 and H2O2 reductions with various e lect rocata lysts ... 

The modified electrode showed a very good stability even at pH 9. Although at this pH a decrease in the redox peaks in CV is observed after 250 cycles, the PB layer is still highly electroactive and sufficient to catalyse the H2O2 reduction. In fact, stirred batch amperometric measurements of H202 (10 pm oil ) were carried out before and after the continuous cycling at pH 9, and the decrease of the signal was only 10% of the initial value. 

The discussed nonlinear phenomena during H2O2 reduction on Pt in acidic media constitute impressive examples of how small differences in the interfacial kinetics owing to structural effects, for example, or to minor changes in the composition of the electrolyte, can affect the dynamic response in a qualitative manner. 

Product of H2O2 reduction by Fenton-type reaction... 

Figure 14 Morse potentials for le and 2e H2O2 reduction illustrating the 10kcalmol more favorable AG forthe latter. (Reproduced by permission of Wiley-VCH)...

Figure 11.3. Sketch of pe°H = 7 and pH = values for four-electron, two-electron, and one-electron redox processes of oxygen compounds. H2O2, O2, OH, and O3 are treated as if they were metastable. Thermodynamically, the OH radical (reduction to H2O) and O3 (reduction to O2) and H2O2 (reduction to H2O) are the strongest oxidants oxygen with regard to its reduction to H2O2 and with regard to its reduction to O2 is a weak oxidant.

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