Platinum oxygen reduction reaction

Obviously, it is not very easy to measure voltage variations inside a piece of iron, but we can artificially transport the oxygen-reduction reaction away from the metal by using a piece of metal that does not normally undergo wet oxidation (e.g. platinum) and which serves merely as a cathode for the oxygen-reduction reaction. 

The mechanism of the oxygen reduction reaction is by no means as fully understood as the h.e.r., and a major experimental difficulty is that in acid solutions (pH = 0) E02/H20 = 1 23, which means that oxygen will start to be reduced at potentials at which most metals anodically dissolve. For this reason accurate data on kinetics is available only for the platinum metals. In the case of an iridium electrode at which oxygen reduction is relatively rapid, a number of reaction sequences have been proposed, of which the most acceptable appear to be the following ... 

Gochi-Ponce Y, Alonso-Nunez G, Alonso-Vante N (2006) Synthesis and electrochemical characterization of a novel platinum chalcogenide electrocatalyst with an enhanced tolerance to methanol in the oxygen reduction reaction. Electrochem Commun 8 1487-1491... 

In this section, we summarize the kinetic behavior of the oxygen reduction reaction (ORR), mainly on platinum electrodes since this metal is the most active electrocatalyst for this reaction in an acidic medium. The discussion will, however, be restricted to the characteristics of this reaction in DMFCs because of the possible presence in the cathode compartment of methanol, which can cross over the proton exchange membrane. 

Parthasarathy A, Srinivasan S, Appleby AJ, et al. 1992b. Pressure dependence of the oxygen reduction reaction at the platinum microelectrode/Nafion interface Electrode kinetics and mass transport. J Electrochem Soc 139 2856-2862. 

Shao MH, Liu P, Adzic RR. 2006b. Superoxide is the intermediate in the oxygen reduction reaction on platinum electrode. J Am Chem Soc 128 7408-7409. 

Yano H, Inukai J, Uchida H, Watanabe M, Babu PK, Kobayashi T, Chung JH, Oldfield E, Wieckowski A. 2006b. Particle-size effect of nanoscale platinum catalysts in oxygen reduction reaction an electrochemical and Pt EC-NMR study. Phys Chem Chem Phys 8 4932-4939. 

Antoine O, Bultel Y, Durand R. 2001. Oxygen reduction reaction kinetics and mechanism on platinum nanoparticles inside Nafion . J Electroanal Chem 499 85-94. 

Durand R, Faure R, Gloaguen F, Aherdam D. 1996. Oxygen reduction reaction on platinum in acidic medium From bulk material to nanoparticles. In Adzic RR, Anson EC, Kinoshita K. editors. Proceedings of the Symposium on Oxygen Electrochemistry. Pennington, NJ The Electrochemical Society. 

Wang B. Recent development of non-platinum catalysts for oxygen reduction reaction. Journal of Power Sources. 2005 152(0) 1-15. 

Figure 5.3. Electrode potential effects on ORR impedance spectra using GDE AC frequency range 6 x 104 to 6 x 10 3 Hz. Electrode potentials (versus SCE) ( ) 0.54 V (+) 0.49 V (x) 0.44 V (o) 0.39 V [6], (Reprinted from Journal of Electroanalytical Chemistry, 499, Antoine O, Bultel Y, Durand R. Oxygen reduction reaction kinetics and mechanism on platinum nanoparticles inside Nafion , 85-94, 2001, with permission from Elsevier.)...

Figure 5.5. Experimental Nyquist diagrams for the ORR on a Pt nanoparticle catalyst (40% Pt/Pt+C) in alkaline solution (1 M NaOH) using an active layer on an RDE at 25°C (EIS frequency range 5 mHz-105 Hz). Electrode potentials (versus Hg/HgO electrode) ( ) -0.02 V ( ) -0.03 V (A) -0.06 V and ( ) -0.08 V [4], (Reprinted from Electrochimica Acta, 48(25-6), Genies L, Bultel Y, Faure R, Durand R. Impedance study of the oxygen reduction reaction on platinum nanoparticles in alkaline media, 3879-90, 2003, with permission from Elsevier.)...

Genies L, Bultel Y, Faure R, Durand R (2003) Impedance study of the oxygen reduction reaction on platinum nanoparticles in alkaline media. Electrochim Acta 48(25-6) 3879-90... 

Savadogo O and Essalik A, 1996, Effect of Platinum Particle Size on the Oxygen Reduction Reaction on 2%Pt-l%H2W04 in Phosphoric Acid. Journal of the Electrochemical Society, 143(6), 1814-1821. 

The preceding statement does not hold true for the oxygen reduction reaction Using platinum as an example, we note that oxygen evolution... 

O. Antoine, Y. Bultel, and R. Durand, "Oxygen Reduction Reaction Kinetics and Mechanism on Platinum Nanoparticles Inside Nafion," Journal of Electro-analytical Chemistry, 499 (2001) 85-94. 

The sluggish oxygen reduction reaction (ORR) in the cathode catalyst layer (CCL) induces a major fraction of voltage losses in PEFCs. Due to the requirement of sufficient membrane humidification, discussed in Sect. 8.2.2, and the limitation it imposes on the working temperature range (< 100 °C) only platinum-based catalysts can provide acceptable reaction rates. Platinum, however, is costly, and its resources are limited. 

Let us consider the oxygen reduction reaction (ORR) that occurs in the cathode of the polymer electrolyte membrane fuel cell (PEMFC), in an acidic environment. Although a variety of ORR mechanisms have been proposed, the four-electron pathway is primarily used to characterize the behavior of this reaction at a platinum electrode or a glassy carbon electrode coated with a platinum-based catalyst. The overall reaction is given by... 

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