Oxygen reduction phosphoric acid

Jalan V, Taylor EJ. 1983. Importance of interactomic spacing in catalytic reduction of oxygen in phosphoric acid. J Electrochem Soc 130 2299-2301. 

Bregoli LJ. 1978. The influence of platinum crystallite size on the electrochemical reduction of oxygen in phosphoric acid. Electrochim Acta 23 489-492. 

Giordano N, Passalacqua E, Pino L, Arico AS, Antonucci V, Vivaldi M, Kinoshita K. 1991. Analysis of platinum particle-size and oxygen reduction in phosphoric-acid. Electrochim Acta 36 1979-1984. 

P.N. Ross, "Oxygen Reduction on Supported Pt Alloys and Intermetallic Compounds in Phosphoric Acid," Final Report, EM-1553, prepared under Contract 1200-5 for the Electric Power Research Institute, Palo Alto, CA, September 1980. 

T. Ito, K. Kato, S. Kamitomai, M. Kamiya, "Organization of Platinum Loading Amount of Carbon-Supported Alloy Cathode for Advanced Phosphoric Acid Fuel Cell," in Fuel Cell Seminar Abstracts, 1990 Fuel Cell Seminar, Phoenix, AZ, November 25-28, 1990. J.S. Buchanan, G.A. Hards, L. Keck, R.J. Potter, "Investigation into the Superior Oxygen Reduction Activity of Platinum Alloy Phosphoric Acid Fuel Cell Catalysts," in Fuel Cell Seminar Abstracts, Tucson, AZ, November 29-December 2, 1992. 

The electrode kinetics of cathodic oxygen reduction at Pt in contact with the acidic polymer is enhanced by a factor of at least 10 compared to aqueous sulfuric or phosphoric acid at temperatures of 50 to 80°C (759) because the sulfonic acid groups interact adsorptively less with Pt than S04 2 or P04 ions, leaving the greater part of the Pt surface free for adsorption of O2. 

In particular, Yeager and co-workers (42) have described a = a 4- j3 T for the reduction of oxygen on platinum in concentrated phosphoric acid in the temperature range 25—250°C with cathodic Tafel slopes nearly independent of temperature (a — 0.08 and j3 = 0.0012/K). The effect of electrode potential on the reaction kinetics is mainly through the entropy of activation [43]. 

Alkaline fuel cells (AFC) — The first practical -+fuel cell (FC) was introduced by -> Bacon [i]. This was an alkaline fuel cell using a nickel anode, a nickel oxide cathode, and an alkaline aqueous electrolyte solution. The alkaline fuel cell (AFC) is classified among the low-temperature FCs. As such, it is advantageous over the protonic fuel cells, namely the -> polymer-electrolyte-membrane fuel cells (PEM) and the - phosphoric acid fuel cells, which require a large amount of platinum, making them too expensive. The fast oxygen reduction kinetics and the non-platinum cathode catalyst make the alkaline cell attractive. 

Figure 6. X-ray diffraction platinum atom nearest neighbour distances versus specific activity for oxygen reduction at 0.9 V in phosphoric acid at 200 °C ( ) Man and Taylor28 and (0) Luczak.

---