Silver and silver-copper electrodeposition from a pyridinium-based ionic liquid

摘要

Silver(I) was extracted from aqueous solutions in the absence and presence of copper(II) with the ionic liquid (IL) 3-butylpyridinium bis(trifluoromethanesulfonyl)imide, [3-BuPyr][NTf_2]. After extraction, silver and silver-copper were electrodeposited on glassy carbon at room temperature from the ionic liquid phase. The mechanism of silver electrodeposition has been studied using electrochemical techniques such as cyclic voltammetry (CV) and chronoamperometry (CA). At suitably overpotentials silver electrocrystallization proceeds via a diffusion controlled mechanism and was analyzed using the Scharifker and Hills model for potentiostatic growth. The growth-nucleation mechanism of silver from the extracted phase is more progressive in character at low overpotentials, while at elevated overpotentials an instantaneous nucleation behavior was determined. In contrast, the silver nucleation closely followed the response predicted for instantaneous nucleation in neat [3-BuPyr][NTf_2]. The electrochemical co-deposit of Ag-Cu was studied by linear sweep stripping voltammetry (LSSV). The resultant electrodeposits were characterized by scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) analysis.