Underpotential Deposition of Silver on Au(111) from an Air‐ and Water‐Stable Ionic Liquid Visualized by In‐Situ STM

Abstract

AbstractThere is a steadily increasing interest in room‐temperature ionic liquids (ILs) as media for metal electrodeposition. However, the fundamental understanding of the underlying surface processes at the electrode/IL interface and of the initial stages of electrodeposition is still at a very preliminary stage. In this article, we investigate the underpotential deposition (upd) of Ag on a well‐defined Au(111) single crystal surface from an air‐ and water‐stable IL, 1‐butyl‐1‐methylpyrrolidinium dicyanamide [BMP][DCA]. By employing in‐situ scanning tunneling microscopy (STM), we could visualize individual stages of the Ag upd process as a function of the applied electrode potential and correlate voltammetric responses to the obtained STM data. The initial Ag upd process results in the formation of an Ag‐(4×4) lattice, which is further transformed into a pseudomorphic Ag‐(1×1) monolayer at the underpotential of ∼40 mV. The structural stability of the Au(111) surface in [BMP][DCA] is also examined in the absence of Ag+ ions in both the negative and positive potential regions.