Electrodeposition of Zn-rich CuxZn(1−x) Films with Controlled Composition and Morphology

Zn-rich CuxZn(1−x) alloy films (60–88 at% Zn) are grown in a pyrophosphate-based bath via potentiostatic deposition as a precursor for the synthesis of nanoporous Cu. Voltammetric studies show a selective negative shift in the reduction potential of Cu after its complexation with pyrophosphate, allowing for co-reduction of Cu and Zn at similar potential ranges. Anodic stripping characterization reveals a distinct three-stage alloy dissolution behavior that enables the estimation of the alloys' compositions. Moreover, a systematic study has been done to determine the optimal conditions for Cu–Zn electrodeposition routines at current efficiency of 63%–73% with precise control over the elemental composition and morphology of the alloy. Scanning electron micrographs reveal highly crystalline and uniform alloy deposits, while energy dispersive X-ray spectroscopy results suggest tunability of the alloys' elemental composition by simple adjustment of the precursor Cu2+:Zn2+ ratio in the deposition bath at the optimized potential of −2.0 V vs MSE. CuxZn(1−x) alloys of similar elemental composition and morphological quality were also electrodeposited on Cu and glassy carbon substrates. Finally, X-ray diffraction patterns of the electrodeposited alloys reveal the presence of CuZn5 and Cu5Zn8 intermetallic compounds that represent brass alloys in the composition range of interest.