Abstract
Zirconia stabilized with 8 mole per cent of scandia has a very high oxygen ion conductivity and can "pump" oxygen from oxygen‐bearing gases thus decomposing them. In this study the rate of decomposition of the air‐pollutant species, nitric oxide, to harmless species (via the reaction: 
) was found to be markedly catalyzed when a potential above 1V was applied across a zirconia disk coated with either a porous platinum or porous gold electrode. It is known that platinum can both form oxides and catalyze the decomposition of 
; whereas, gold does neither. The catalytic decomposition of 
on platinum metal is inhibited by 
, such behavior being attributed to preferential chemisorption of 
over 
as well as the possible formation of an inhibiting platinum oxide surface. The original rationale for this investigation was the possibility that the decomposition of 
might be enhanced if
were electrolytically "pumped" away from a platinum electrode deposited on zirconia, keeping the platinum oxygen‐free. However it was not anticipated that at high potentials dissociation rates a thousandfold that on nonporous platinum electrodes occur in the presence of either a platinum or gold porous electrode. No reactivity at all was observed on a nonporous gold electrode. These results suggest that catalysis occurs mainly on a surface other than the platinum or gold, namely, on the zirconia surface itself. It is proposed that F‐centers on the zirconia surface formed by the applied potential are primarily responsible for the observed enhanced catalysis.