Effects of cathodic hydrogen evolution on electrodeposited Au-Cu-Cd alloys

Hydrogen can be incorporated into electrodeposited Au alloys either during electrodeposition or by cathodic charging. Incorporated hydrogen in these a lloys generally impairs their mechanical properties. In this work, we prese nt results of a study of electrochemical, structural, surface composition, and morphological effects of cathodic charging of Au-Cu-Cd alloys electrode posited from a cyanoalkaline bath. Different kinds of linear sweep voltamme tric behaviors are observed for alloys with different compositions and for repeated scans, which is related to a loss of electrocatalytic activity for high Cu content alloys and prolonged cathodic charging. The surface compos ition of alloys is altered by cathodic charging, resulting in a decrease in Au content. The surface morphology, as observed by scanning electron and a tomic force microscopies, is modified by cathodic charging: large crystalli tes are attacked and globular features appear on Bat deposits. The crystall ographic structure of the alloys is affected by prolonged hydrogen evolutio n; the original preferred orientation is disrupted and a Cu-rich phase appe ars. (C) 2001 The Electrochemical Society.