Accession Number : AD0649570

Title :   POTENTIOSTATIC CURRENT-POTENTIAL MEASUREMENTS ON A PLATINUM ELECTRODE IN A HIGH-PURITY CLOSED SYSTEM.

Descriptive Note : Interim rept.,

Corporate Author : NAVAL RESEARCH LAB WASHINGTON D C

Personal Author(s) : Schuldiner,S. ; Warner,T. B. ; Piersma,B. J.

Report Date : 06 MAR 1967

Pagination or Media Count : 23

Abstract : In a high-purity, closed, electrochemical system, voltage regions at which very slow reactions are rate-controlling, were accurately separated and measured. In the potential range from 0.06 to 0.13 volt, the rate-controlling step is Pt-H + H(+) + e = H2 under conditions of rapid stirring with helium. A second region between 0.30 and 0.46 volt indicated a slow hydrogen-ion discharge. In the anodic range from 0.46 to >2 volts, four distinct regions were found: a region in which oxidizable impurities reacted; a region at which water was probably oxidized to give chemisorbed OH; a region in which chemisorbed and dermasorbed O was formed; and a region in which O2 was generated. Maximum oxidizable and reducible impurity levels were quantitatively determined both in solution and as adsorbed species on the working electrode surface. It is shown that the impurity levels were very low. Very small additions of hydrogen or oxygen in the critical transition region (net cathodic to anodic reactions) did not appear to have catalytic effects. However, at oxygen partial pressures above 0.0000001 atm, a poisoning effect was apparent. (Author)

Descriptors :   (*FUEL CELLS, *ELECTRODES), (*PLATINUM, ELECTROCHEMISTRY), ELECTROSTATICS, VOLTAGE, REACTION KINETICS, HYDROGEN, OXIDATION REDUCTION REACTIONS, IMPURITIES, CHEMISORPTION, OXYGEN, WATER, CATALYSIS, INHIBITION

Subject Categories : Physical Chemistry
      Electric Power Production and Distribution

Distribution Statement : APPROVED FOR PUBLIC RELEASE