First observation of an ordered sulfate adlayer on Ag single crystal electrodes

Sulfate adsorption on Ag(1 1 1) and Ag(1 0 0) in 0.1 M H2SO4 has been studied by cyclic voltammetry and in situ STM. An ordered adlayer of sulfate or bisulfate has been found on the (1 0 0) and (1 1 1) faces of well-prepared silver single crystal electrodes for the first time. With a new preparation method involving inductive heating, which allows to exclude oxygen during the annealing procedure, high quality Ag(1 1 1) and Ag(1 0 0) surfaces were obtained. Unlike for other (1 1 1) surfaces of fcc metals, an unusual c(3 × 33) adlayer structure has been found for Ag(1 1 1). On Ag(1 0 0) an incommensurate (1.3 × 3) structure was observed. No ordered adlayer has been found on Ag(1 1 0).