Formic acid oxidation on pure and Bi-modified Pt(111): Temperature effects

Temperature effects on the kinetics of formic acid electrooxidation are stu died on Pt(111) and on Pt(111) modified by irreversibly adsorbed Bi under b oth potentiodynamic and potentiostatic conditions. We propose two modes of action of irreversibly adsorbed Pi on the kinetics of HCOOH oxidation: (i) the inhibiting effect due to a blocking of active Pt sites and (ii) the cat alytic effect due to the enhanced adsorption of OHad on the Pt sites adjace nt to Bi. This counteracting behavior led to the fact that under steady-sta te conditions no difference in the overall activity was observed between Pt (111) and Pt(111)/Bi. Therefore, Pt(111)/Bi does not represent a catalytica lly active system of technological relevance.