Electrochemical kinetic studies are reported on the anodic oxidation of ammonia in aqueous potassium hydroxide solutions a t platinum black electrodes. A kinetic scheme of consecuti\~e reactions is proposed; Tafel slopes are deduced for various rate-determining mechanisms and compared with the experimental behavior. The reaction pathway is correlated with that iilvolved in the analogous catalyzed ammonia vapor decomposition. The exchange currents obtained, compared with those for hydrogen oxidation, render the system u~lfavorable for fuel cell applications.

Electrodeposition of zinc onto foil electrodes from alkaline zincate solutions with direct current results in dendritic or black, porous mossy deposits. Smoother deposits are obtained with a pulsed current source or periodic reversal of current. The nature of the deposit with pulsed charging depends on the current density, the amount of charge passing through the electrolytic cell, the on time, and off time. The optimum values of these parameters are dependent on the cell geometry and the differences between the apparatus used in the present study and a cell containing a secondary zinc electrode are discussed.

A highly dispersed platinum catalyst (platinum crystallite size less than 15Aå) on a conductive carbon support was prepared. These doped carbons were made into Teflon‐bonded fuel cell electrodes and the platinum surface area and the dispersed platinum specific activity (i.e., the activity per unit area of platinum) for oxygen electroreduction in acid electrolyte was determined. The specific activity of the dispersed platinum was found to be approximately twenty times less than that of crystalline platinum black. The lower activity of this catalyst compared with that of platinum black may be due either to the difference in the platinum crystallite sizes, or to the influence of the support on the platinum activity, or to a combination of both these factors.

No abstract

Apparatus and technique for cathodic reduction of α‐Fe2O3 films is described. Measurements of the reduction efficiency in buffered and unbuffered electrolytes are given. Effects of pH of the electrolyte, dissolved oxygen current density, and film thickness are noted and discussed. Electrolytes containing “ferrous‐complexing” ions have also been investigated. Methods of determining quantities of α‐Fe2O3 in thin films are suggested and their limits of accuracy considered.