Precursor Adsorption of SbBr3 on Au(111) and Au(100) for Antimony Underpotential Deposition in a BMIBF4 Ionic Liquid-A Comparison with SbCl3

摘要

By employing in-situ STM, we have studied precursor adsorption and initial stage of Sb UPD on Au(111) and Au(100) in a SbBr3-containing BMIBF4 ionic liquid. It has been observed that the adsorption of SbBr3 selectively takes place on Au(100), in contrast to that of SbCl3, with formation of chains with (_(1 5)~(3 0)) structure as well as squares with (_(-1 6)~(6 1)) structure. The chains are composed of pairs of SbBr3 molecules, which are bridged with the adjacent SbBr3 molecules in the chain to form the anisotropy along either of the two characteristic directions of Au(100). The square configured structure is composed of periodically arranged monomeric and dimeric SbBr3, which will gradually replace the chain structure. Regardless of the precursor adsorption, however, the initial stage of Sb UPD is characterized by the formation of atomic strips, like in the SbCl3-containing system, which reveals the consistency of discharging behavior of Sb(III) from the SbCl3 and SbBr3 molecules. Together with the findings from me SbCl3-containing system, the results are discussed in view of matching of structures between the pyramidal antimony tri-halides and the crystalline surfaces. The role of the ionic liquid as well as properties of the electrified interface will also be mentioned.