Chemistry of oxygen, reduction

It is important to compare the catalytic properties of Prussian blue with known hydrogen peroxide transducers. Table 13.2 presents the catalytic parameters, which are of major importance for analytical chemistry selectivity and catalytic activity. It is seen that platinum, which is still considered as the universal transducer, possesses rather low catalytic activity in both H202 oxidation and reduction. Moreover, it is nearly impossible to measure hydrogen peroxide by its reduction on platinum, because the rate of oxygen reduction is ten times higher. The situation is drastically improved in case of enzyme peroxidase electrodes. However, the absolute records of both catalytic activity... 

Figure 3, Standard reduction potentials associated with the chemistry of oxygen values in upper and lower halves of diagram refer to pH 0,0 and pH 7,0 conditions,...

Anderson and his coworker carried out a series quantum chemistry studies of oxygen reduction reactions.52-57 Anderson and Abu first studied reversible potential and activation energies for uncatalyzed oxygen reduction to water and the reverse oxidation reaction using the MP2/6-31G method. The electrode was modeled by a non-interacting electron donor molecule with a chosen ionization potential (IP). The primary assumption is that when the reactant reaches a point on the reaction path where its electron affinity (EA) matched the donor IP, an electron transfer is initialized. The donor s IP or reactant s EA was related to the electrode potential by,... 

A detailed catalytic cycle that corresponds to the proposed model is shown in Figure 4.8. We are not going discuss the details of chemistry involved in the catalysis of oxygen reduction the interested reader is referred to the original papers. Refs. [22,26]. 

Before we go onto OH and O3 chemistry, we now turn to hydrogen peroxide H2O2 or HOOH, which is seen in (5.102) as the final product of oxygen reduction but which is also considered an intermediate because of its reactivity in aqueous solution (in contrast to the gas phase). In Chapter 1.3.3 we cited Proufs notable idea on the existence of H2O2 in air (just after its discovery by Thenard in 1818) and the bleaching qualities of dew . Dew, surface droplet water in intensive contact with the surrounding air and the underlying surface, often provides plants with chromo-... 

More recent reviews on the electro catalysis of oxygen reduction in PEFC have been given in [23,49]. Surface chemistry of platinum, particularly the coverage of the metal surface with oxygen containing species above a potential of 750 mV vs. RHE caused difficulties in the kinetic description of the oxygen reduction reaction. 

Wang, H. Xie, K, Investigation of Oxygen Reduction Chemistry in Ether and Carbonate Based Electrolytes for Li-02 Batteries. Electrochimica Acta 2012,64,29-34. 

Johnson, L. and Walsh, D.A. (2012) Tip generation-substrate collection-tip collection mode scanning electrochemical microscopy of oxygen reduction electrocatalysts. Journal of Elec-troanalytical Chemistry, 682, 45-52. 

Figure 2.17. Tafel plots for oxygen reduction reaction at a Pt working electrode [8]. (Reprinted from Journal of Electroanalytical Chemistry, 574(2), Wakabayashi Noriaki, Takeichi Masajoiki, Itagaki Masayuki, Uchida Hiroyuki and Watanabe Masahiro, Temperature-dependence of oxygen reduction activity at a platinum electrode in an acidic electrolyte solution investigated with a channel flow double electrode, 339-46, 2005, with permission from Elsevier.)...

Figure 5.18. Proposed redox cycle for the electrocatalytic reduction of oxygen to hydrogen peroxide on Co(II) hydroxide [99]. (Reprinted from Journal of Electroanalytical Chemistry, 599(2), Wass Tobias Johnsson JR, Panas I, Asbjomsson J, Ahlberg E. Quantum chemical modelling of oxygen reduction on cobalt hydroxide and oxyhydroxide, 295-312, 2007 with permission from Elsevier.)...

Stamenkovic, V., T.J. Schmidt, P.N. Ross et al. 2002. Sruface composition effects in electro catalysis Kinetics of oxygen reduction on well-defined Pt3Ni and Pt3Co alloy srufaces. Journal of Physical Chemistry B 106 11970-11979. 

Chen, C.-H. Meadows, K. E. Cuharuc, A. Lai, S. C. Unwin, P. R., High resolution mapping of oxygen reduction reaction kinetics at polycrystalline platinum electrodes. Physical Chemistry Chemical Physics 2014,16, 18545-18552. 

Electrocatalysis of oxygen reduction and small alcohol oxidation in alkaline media. Physical Chemistry Chemical Physics, 9 (21), 2654-2675. 

Wang, J., Markovic, N. Adzic, R. (2004). Kinetic analysis of oxygen reduction on Pt(lll) in acid solutions Intrinsic kinetic parameters and anion adsorption effects. Journal of Physical Chemistry B 108(13) 4127-4133. 

H. Wang and K. Xie, Investigation of oxygen reduction chemistry in ether and carbonate based electrolytes for Li-Oj batteries, Electrochim. Acta 64,2012,29-34. 

Generally the oxidant is compounded in one part of the adhesive, and the reductant in the other. Redox initiation and cure occur when the two sides of the adhesive are mixed. There also exist the one-part aerobic adhesives, which use atmospheric oxygen as the oxidant. The chemistry of the specific redox systems commonly used in adhesives will be discussed later. The rates of initiation and propagation are given by the following equations ([9] p. 221). 

---