Effect of Li on the adsorption of CO and O on Pt

The effect of Li preadsorption on the kinetics of CO and oxygen adsorption on a polycrystalline Pt surface has been investigated using the reverse fla sh method. Li preadsorption hardly affects the initial sticking coefficient s for CO and oxygen, while their saturation coverages, attained at room tem perature, are substantially decreased. The results are compared with data r eported for other alkalis, and the physical factors that determine the prom oting ability of electropositive adsorbates in gas adsorption kinetics and catalytic reactions are discussed.