Hydrogen peroxide decomposition theories

It follows from this theory that hydrogen peroxide is to be regarded as a reduction product of the oxygen molecule, and not as an oxidation product of the water molecule. Such a conception, though fundamentally different, was not entirely new. Weltzien 2 had already in 1860 suggested the same idea, and it receives support, Traube points out, from the heat liberated when hydrogen peroxide is decomposed. For if hydrogen peroxide were produced by the oxidation of water, already formed, an absorption of heat would be expected upon decomposition. 

III H) 1910-1 Lotka, A. Contribution to the Theory of Periodic Reactions, J. Phys. Chem. vol. 14, (III C) 1975 Marek, M., Svobodova, E. Nonlinear Phenomena in Oscillatory Systems of Homogeneous Reactions-Experimental Observations, Biophysical Chemistry, vol. 3, 263—273 (III A) 1974 Matsuzaki, I., Nakajima, T., Liebhafsky, H. A. The Mechanism of the Oscillatory Decomposition of Hydrogen Peroxide by the I2-IO3-couple, Chem. Letters (Japan) 1463-1466 (IIT O) 1969 Nakamura, S., Yokota, K., Yamazaki, I. Sustained Oscillations in a Lactoperoxidase, NADPH and 02 system Nature vol. 222, 794... 

In both theories considered above, which have been current for many years, it will be seen that the decomposition of hydrogen peroxide into oxygen and water is always accompanied by the stoichiometric formation of the peroxidic intermediate or an equivalent amount of oxidation and reduction of the catalyst. However, from recent work it appears that this need not always be the case. Thus Haber and Willstatter (3) in a speculative paper, which attempted to explain certain aspects of some... 

The catalytic decomposition of hydrogen peroxide on solid and colloidally dispersed metals has been studied particularly by Bredig et al. (20). These reactions have been treated by Weiss (21) from the point of view of the radical mechanism. On the basis of the electron theory the metal can be considered both as a source and as a sink of electrons. In conformity with the electron transfer processes outlined above, the reactions at the surface of the metal catalyst can be considered to be represented by processes of the type ... 

There are two opposite points of view on the interpretation of the reduction mechanism (and also oxidation mechanism) of hydrogen peroxide on platinum according to one, it is a purely electrochemical process, and according to the other, the deciding role is played by chemical stages (oxidation of the metal by the peroxide and catalytic decomposition of the peroxide at the electrode surface). This difference in approach has already been mentioned when discussing decomposition in the absence of current. At the present time the purely electrochemical theory has practically no supporters, but there is still a large amoimt of controversy about the details of the process. 

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