Hydrogen peroxide electrode behaviour

This is observed for example with a solution containing Fe(III) ions and hydrogen peroxide Fe(II) ions formed at the electrode are converted back to Fe(III) ions by the hydrogen peroxide such behaviour results in an enhanced diffusion wave. 

Electrode behaviour at high hydrogen peroxide concentrations... 

Unlike the RDE technique, which is quite popular for characterizing catalyst activities, the gas diffusion electrode (GDE) technique is not commonly used by fuel cell researchers in an electrochemical half-cell configuration. The fabrication of a house-made GDE is similar to the preparation of a membrane electrode assembly (MEA). In this fabrication, Nation membrane disks are first hot-washed successively in nitric acid, sulphuric acid, hydrogen peroxide, and ultra-pure water. The membranes are then coated with a very thin active layer and hot-pressed onto the gas diffusion layer (GDL) to obtain a Nation membrane assembly. The GDL (e.g., Toray paper) is very thin and porous, and thus the associated diffusion limitation is small enough to be ignored, which makes it possible to study the specific kinetic behaviour of the active layer [6],... 

The behaviour of the glass electrode has also been examined.42-43 The glass-calomel electrode system yields stable and reproducible potentials which vary in the normal way with changes in hydrogen ion concentration. However, the EMF of the couple shifts several hundred millivolts as the solution composition changes from water to hydrogen peroxide. Table 1.2 summarizes the apparent and true pH of aqueous solutions of hydrogen peroxide. 

These modified electrodes did not create voltammetric signals in the presence of PHGPx alone or after incubation of PHGPx with hydrogen peroxide as measured between + 500 and - 600 mV. However, a distinct reduction current was induced by the addition of GSH to PHGPx preincubated with hydrogen peroxide. This was manifested by the appearance of a wave in the cyclic voltammogram at a potential of -280 mV (Fig. 2.8). This is in contrast to the behaviour of heme peroxidases. 

Reduction Behaviour of Hydrogen Peroxide at the Ti02 Electrode... 

The fact that the photosynthesis of hydrogen peroxide on irradiated titanium dioxide suspensions is manifestly ineffective is easily understood when one examines together the cathodic and the photoanodic behaviour of H2O2 at a Ti02 electrode . Thus, the reduction of the HOJ ions... 

Figure 2.15. The anthraquinone process (AO process) to produce H2O2 [30]. (With kind permission from Springer Science+Business Media Journal of Applied Electrochemistry, Electrochemical reduction of 2-ethyl-9,10-anthraquinone (EAQ) and mediated formation of hydrogen peroxide in a two-phase medium Part I Electrochemical behaviour of EAQ on a vitreous carbon rotating disc electrode (RJ5E) in the two-phase medium, 29, 2004, 11-16, A. Huissoud, Scheme 1, 3Springer.)...

Sometimes, currents may be found which are many times larger than would be expected for a diffusion-controlled process. These are found when a species is reduced at the dropping electrode to form a product which rapidly reacts chemically with some other species in the solution to regenerate the original depolarizer. Such behaviour is shown by ferric species in the presence of hydrogen peroxide, the reaction scheme being simply... 

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