Preparation and evaluation of electrocatalysts for phosphoric-acid fuel cells. Final technical report, May 1, 1978-December 31, 1979

The overall objective of this electrocatalysis program was to define the feasibility of lowering the electrocatalyst cost and to increase the electrocatalyst activity in phosphoric acid fuel cells to improve the commercial viability of fuel cells for producing electric power. Highly dispersed platinum was placed on carbon supports. These catalysts were characterized for both the platinum surface areas and crystallite sizes. For a given carbon impregnation technique with the noble metal salt, a definite correlation between the specific surface area of the derived platinum crystallites and the BET surface area of the carbon support was found. A high dispersion of platinum was achieved on a novel high surface area catalyst support - CONSEL. Using high resolution phase contrast electron microscopy, the crystal lattice of highly dispersed platinum on carbon was resolved and, with the lattice images of graphitic carbon black as an internal calibration, the lattice spacing for a small crystallite of platinum was measured within 2% of the value for bulk platinum. Twenty-one catalysts were formulated with variations in the type of carbon support, the platinum metal loading, and the platinum crystallite size. Characteristics and test results are described. (WHK