Study of the influence of nitrite anions on the electrode processes in ammonium electrolyte for Ag-Cu deposition

By means of the cyclic voltammetry (CV) the effect of nitrite anions (in the form of NaNO2) on the kinetics of separate and of codeposition of Ag and Cu is examined. The effect of the electrode substrate and the proportion of the basic components of the solution on the deposition kinetics and the powder formation of Ag-Cu alloys is also established. It is found that the one step process of silver deposition in the absence of nitrite anions is fully reversible. In presence of nitrite anions in the solution, the stage of reduction of the silver-ammonium complexes is preceded by reversible chemical reaction of AgNO2 formation. The copper in nitrite ions absence and presence is deposited by twostage mechanism – incomplete reduction of the cupri-ammonium ions to cupro-ammonium ions and the main process of electrodeposition of cupri-ammonium ions to elementary copper. As a whole the presence of NO2 - ions and the decrease of the Ag + /Cu 2+ - ratio in the electrolyte impedes the Ag and Cu electrodeposition and results in production of more