ИСТИНА

Electrodeposition of Cr is of great practical importance. However, Cr plating from aqueous Cr(III) solutions is accompanied by intense hydrogen evolution and characterized by low current efficiency. Hence it is of great interest to use alternative chromium plating electrolytes that would be free of the above disadvantages. Air- and water-stable room-temperature ionic liquids (ILs) can be such an excellent alternative medium for metal deposition [1]. ILs possess good intrinsic ionic conductivity, nonvolatility, high thermal stability, and a wide electrochemical window. These features caused vast interest in studying ILs as deposition electrolytes [2], but fundamental understanding of the electrodeposition processes in ILs is only at a preliminary stage. This study is focussed on exploring the possibility of Cr electrodeposition on various supports (Pt and Au single crystals, polycrystalline Pt, and glassy carbon) from Cr(III) solutions in ILs with dicyanamide anion. We attempt to reveal the effect of the substrate material and surface structure at the initial stages of the electrodeposition. For this, we employ conventional electrochemical techniques in combination with in situ and ex situ scanning probe microscopy (STM and AFM). We show significant difference in the Cr deposition process on Pt and Au electrodes. The tuning of the deposition conditions allows obtaining deposits of different morphologies on Pt(111) electrodes, ranging from two-dimensional Cr islands (Figure 1) to compact low–roughness layers at low and high overpotentials, respectively.