Vacancy dynamics on CO-covered Pt(111) electrodes

Abstract

In situ video-STM studies of Pt(111) electrodes in CO-saturated 0.1 M H₂SO₄ solution are presented, which reveal the presence of defined point defects in the CO pre-oxidation regime, where the surface is covered by a highly dynamic apparent (1 × 1)-CO adlayer. These defects are generated at the Pt steps and can switch between a mobile and an immobile state. They are assigned to diffusing vacancies in the Pt surface layer, induced by interaction of the highly mobile CO adsorbates with Pt surface atoms at potentials as low as 0.30 V_Ag/AgCl.