Electrodeposition of Ag from nitrate solutions : Part I. Effect of phosphate ions on morphology

Abstract

The initial steps of silver deposition from nitrate solutions on silver and platinum substrate were studied. The formation of boulders was observed on both substrates, their growth onto platinum being the more regular. A compact Ag-surface film was not produced under the applied conditions, even after prolonged deposition. Instead, growth of (i) independent large Ag grains occurred at lower overpotentials and (ii) dendrites formed at higher overpotential values. In the presence of phosphate in unstirred solutions 2D and/or 3D dendrites were formed at lower and higher overpotentials, respectively. Increase in electrolyte temperature above 25∘C was found to cause dendrite coarsening, even at lower overpotentials. In stirred solutions compact Ag-surface films were deposited over a wide range of overpotentials, showing different structural features depending on the applied overpotential.