Electrodeposition of β′‐Brass from Cyanide Baths with Accumulative Underpotential Deposition of Zn

Abstract

Cu‐Zn alloys were deposited under potentiostatic conditions from cyanide baths with varied concentration ratio but with the same free concentration. The Zn content of the deposits showed the maximum at around −1.4 V vs. Ag/AgCl as a function of the applied potential. The deposits obtained at −1.4 V vs. Ag/AgCl had the composition near CuZn, and the β′‐brass superlattice whose structure is the CsCl type, was independent of the concentration ratio of the baths. In the absence of in the bath, elemental Zn was deposited only at potentials negative to −1.5 V vs. Ag/AgCl and the Zn electrode was dissolved in the bath at −1.4 V vs. Ag/AgCl. This shows that Zn was codeposited with Cu forming the β′‐brass deposits in the underpotential deposition region. The β′‐brass deposits were formed through the accumulative underpotential deposition of Zn onto the electrodeposited Cu atom. The underpotential deposition of Zn onto Cu was confirmed from the cyclic voltammograms of a Cu electrode. © 2000 The Electrochemical Society. All rights reserved.