Voltammetric study of the influence of EDTA on the silver electrodeposition and morphological and structural characterization of silver films

The electrodeposition of silver onto platinum from an alkaline electrolyte containing EDTA (ethylenediaminetetraacetic acid) was investigated. Voltammetric studies indicated that the reduction process is influenced thermodynamically and kinetically by the EDTA concentration. Moreover, hydrodynamic studies showed that silver deposition involved different silver complexes, depending on the EDTA concentration. Scanning electron microscopy analysis showed that the presence of EDTA in the plating bath was beneficial, since the silver films coated the substrate completely, regardless of the EDTA concentration. Furthermore, the silver films were uniform, without cracks and with fine granularity, while in the absence of EDTA the granularity was rough. Energy dispersive X-ray spectroscopy showed that carbon was not incorporated into the silver films. X-ray diffraction analysis of the Ag deposits obtained at various EDTA concentrations indicated the occurrence of polycrystalline silver and that the main orientation was (1 1 1), as found in the silver film obtained from a cyanide bath.