Two electrochemical processes for the deposition of Sb on Au(100) and Au(111): irreversible adsorption and underpotential deposition

We report the voltammetric studies on the depositing behavior of Sb on Au(100) and Au(111) electrodes. It was found that two electrochemical processes are involved in depositing the metallic Sb layer of full coverage (theta congruent to 0.43) on the investigated electrode surfaces. One of the processes is the reduction of the irreversibly adsorbed oxygenous Sb layer, which is formed upon contact between Au electrodes and Sb-containing solution. The coverage of the metallic Sb layer obtained via the irreversible adsorption was 0.33 on both electrodes. The other process to complete the full monolayer deposition of Sb is the underpotential deposition of the oxygenous Sb species in solution. The deposition sites for the underpotential deposition process are proposed to be the vacancies generated during the reduction of the irreversible adsorbates of Sb, and a possible phase transition in the deposited Sb layer on Au(111) is discussed. (C) 1997 Elsevier Science S.A.