First demonstration of in situ electrochemical control of a base metal catalyst: Spectroscopic and kinetic study of the CO plus NO reaction over Na-promoted Cu

Controlled, reversible electrochemical promotion (EP) of a base metal catal yst has been demonstrated for the first time. Electropumping of Na from a b eta" alumina solid electrolyte to a Cu film catalyst results in large impro vements in both activity and selectivity of the latter. In the catalytic re duction of NO by CO, the reactive behavior, surface composition, and respon se to EP are a strong function of the composition of the reactant gas. Elec tron spectroscopic data show that these effects are due to pumping of Na to the catalyst when, under reaction conditions, it is present as NaNO3 on an oxidized Cu surface. Taken together, the spectroscopic and reactor results show that Cu-0 sites are not of significance and that the catalytically ac tive surface is dominated by Cu+ and Cu2+ sites. They also suggest that Cu is of principal importance for the dissociative adsorption of NO and that EP is due to Na-induced enhancement of the adsorption and dissociation of N O at these sites.