Effect of 1-Butyl-1-Methylpyrrolidnium Dicyanamide on the Structure of Pd Electrodeposit

Abstract

One of the most widely investigated applications of ionic liquids (ILs) is electrodeposition (1). Wide electrochemical window, good conductivity, metal complexing ability, and low water content are the advantages of doing electrodeposition in ILs. Electrodeposition of metals from every group of the periodic table has been studied (2). One of such metal is Pd, which has hydrogen embrittlement issues in aqueous-based solutions. In ILs, the embrittlement issue could be avoided (3). Although many ILs have been tried for Pd electrodeposition, the morphology of the electrodeposit has often been often been powdery and prone to cracks (3-5). Understanding the structure of the Pd electrodeposited in ILs could reveal ways to improve its morphology. In this work, structure of the Pd electrodeposited in 1-butyl-methylpyrrolidinium dicyanamide ([Bmpyrr][DCA]) is studied. Due to the metal complexing ability of [DCA]- anions, previous works have shown that [Bmpyrr][DCA] is a suitable room-temperature ILs to electrodeposit Pd (6, 7). After electrodeposition, we found significant presence of nitrogen on the Pd deposits through X-ray photoelectron spectroscopy (Figure 1). Since the source of nitrogen cannot be atmosphere, we hypothesized that the nitrogen was from [Bmpyrr][DCA] tethered to the Pd electrodeposit. This raises interesting questions as to the role of ILs in the structure of the Pd deposits. We will present further characterization of the Pd deposits using X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron microscopy (XPS) to study the role of [Bmpyrr][DCA] on structure of the Pd deposit.