Oxygen reduction reaction in alkaline medium

Feng Y, Alonso-Vante N. Carbon-supported cubic CoSe2 catalysts for oxygen reduction reaction in alkaline medium. Electrochim Acta 2012 72(0) 129—33. 

Nitrogen-doped carbon nanotubes as a cathode catalyst for the oxygen reduction reaction in alkaline medium. Electrochem. Commun., 12 (3), 338- 341. 

Oliveira MC, Rego R, Fernandes LS, Tavares PB (2011) Evaluation of the catalytic activity of Pd-Ag alloys on ethanol oxidation and oxygen reduction reactions in alkaline medium. J Power Sources 196(15) 6092-6098... 

Mamuru SA, Ozoemena KI (2010) Iron (II) tetrakis(diaquaplatinum) octacarboxyphtha-locyanine supported on multi-walled carbon nanotubes as effective electrocatalyst for oxygen reduction reaction in alkaline medium. Electrochem Commun 12(11) 1539-1542... 

Li ZP, Liu ZX, Zhu KN, Li Z, Liu BH (2012) Synergy among transition element, nitrogen, and carbon for oxygen reduction reaction in alkaline medium. J Power Sources 219 163-171... 

The advantage of AFCs over the other systems lies in the fact that the reduction of oxygen to OH- is much faster than the acidic equivalent of oxygen to H20 due to a better kinetics, which makes the AFC a more efficient system [15]. The hydrogen oxidation reaction in alkaline medium, however, is slower. 

Jiang L, Cui L, He X. Cobalt-porphyrin noncovalently functionalized grapheme as nonprecious-metal electrocatalyst for oxygen reduction reaction in an alkaline medium. J Solid State Electrochem 2015 19 497-506. 

In summary, little work has been done in past years to better understand electrocatalysts in alkaline medium and to develop new effective catalysts for this new and promising alkaline membrane fuel cell technology. Moreover, almost no work has been done in real alkaline membrane fuel cells with catalysts other than platinum. The development of non-Pt and non-Pt group metal (non-PGM) catalysts toward oxygen reduction reaction for alkaline membrane fuel cells now requires further research in order to make this a real affordable technology. 

Most reactions with hydrazine are carried out with aldehydes and ketones in the presence of alkali. The reduction proper is preceded by formation of hydrazones that decompose in alkaline medium at elevated temperatures to nitrogen and compounds in which the carbonyl oxygen has been replaced by two hydrogens. The same results are obtained by alkaline-thermal decomposition of ready-made hydrazones of the carbonyl compounds. Both reactions are referred to as Wolff-Kizhner reduction [280]. 

The reverse reaction, dissolved O2 reduction in alkaline and acid solutions, was also studied [117, 118]. The reduction was found to be highly inhibited, probably due to the lack of adsorption sites for oxygen and/or reduced intermediates. The reaction is hypothesized to proceed mainly at sp3-sites the non-diamond sp2 carbon was deactivated by anodic prepolarization. The kinetic parameters were found as a = 0.24, k° = 7 10-5 cm s-1 in alkaline medium. It is significant that, owing to its high overvoltage, the dissolved O2 reduction does not interfere with other reactions, which thus can be studied on diamond electrodes without air removal from the cell this could be advantageous in certain types of analytical applications. 

However, due to a different experimental setup, the assignation of these species could not be confirmed from the infrared spectroscopy measurements carried out on a gold catalyst in alkaline medium, " which was found to present an exclusive series of oxygen reduction pathway. " The presence of these species as intermediates in the ORR mechanism was observed by Raman spectroscopy coupled with electrochemistiy in acidic medium on a gold electrode with bismuth adatoms. " Later, this mechanistic study of ORR by Raman spectroscopy was extended to a gold electrode in alkaline medium "" with an evidence for O2 formation as a reaction intermediate. H02 was also identified, but as a product of the ORR in alkaline medium. 

Restovic A, Rios E, Barbato S, Ortiz J, Gautier JL (2002) Oxygen reduction in alkaline medium at thin MnxCo3 x04 (0 < x < 1) spinel films prepared by spray pyrolysis. Effect of oxide cation composition on the reaction kinetics. J Electroanal Chem 522(2) 141-151... 

In this chapter, recent results on the oxygen reduction reaction will be covered. We will focus on the results obtained with gold nanoparticles. However, some results obtained with single-crystal electrodes will be presented since they are necessary to understand the results found for the nanoparticle electrodes. Although the mean electrocatalytic activity of the gold electrode is lower than that of platinum, Au(lOO) electrode in alkaline medium has a similar activity for the ORR than platinum, and for that reason, it has been studied systematically and abundantly. 

The oxygen reduction reaction overpotential loss in alkaline membrane fuel cells is very similar to that in proton exchange membrane fuel cells, i.e., the cathode overpotential loss remains an important factor limiting the efficiency and performance of alkaline membrane fuel cells [6, 7]. However, switching to an alkaline medium as in alkaline membrane fuel cells allows for the use of... 

Whereas research on oxygen reduction reaction catalysts in the alkaline medium has only now begun, studies on hydrogen oxidation reaction catalysts for alkaline membrane fuel cells constitute an entirely unexplored field. 

Moa G, liao S, Zhang Y, Zhang W, Ye J (2012) Synthesis of active iron-based electrocatalyst fm the oxygen reduction reaction and its unique electrochemical response in alkaline medium. Electrochim Acta 76 430-439... 

As described before in this chapter, conventional DEFCs can be divided into two types as a function of fhe employed membrane, namely proton exchange membrane DEFCs (PEM-DEFCs) and anion exchange membrane DEFCs (AEM-DEFCs), used in acidic and alkaline medium, respectively. As previously reported, Pt-based catalysts undergo rapid poisoning of the catalytic sites, which compromises cell performance. On the other hand, the kinetics of both ethanol oxidation (OER) and the oxygen reduction reaction (ORR) in alkaline medium are much faster than the corresponding kinetics in acidic medium, which substantially improves cell performance. The main limitation to the cell performance in AEM-DEFCs is the physical and chemical stability of the AEM [71]. Another problem encountered with the AEM is that its ionic conductivity is about one order of magnitude lower than that of Nafion membranes. 

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