In Situ STM Studies on the Underpotential Deposition of Antimony on Au(111) and Au(100) in a BMIBF4 Ionic Liquid

Abstract

In this article, the underpotential deposition (UPD) of Sb on Au(111) and Au(100) over a wide potential range in a BMIBF4 ionic liquid containing SbCl3 is investigated by cyclic voltammetry and in situ scanning tunneling microscopy (STM). The cyclic voltammograms of the two surfaces show similar features of Sb UPD, which is kinetically sluggish at high underpotential shift but rapid at low underpotential shift with a large and broad reduction peak. The total charge flux associated with the UPD suggests an equivalent of nearly 1 ML quantity of Sb deposit. In situ STM results showed precursor adsorption and several stages of the UPD. The prior UPD reversible adsorption of SbCl3 precursor occurs only on Au(111) with an ordered hexagonal array of six- and seven-membered clusters in (√31 × √31)R8.9° registration with the Au(111) surface. On both Au(111) and Au(100), the initial stage of Sb UPD (from −0.2 to −0.4 V) proceeds with the formation of similar short atomic strips of Sb atoms with a length of 2−2.5 nm...