Compositional Control in Electrodeposited Ni (subscript x) Pt (subscript 1-x) Films

Published

October 29, 2007

Author(s)

J Mallett, Erik B. Svedberg, John E. Bonevich, Alexander J. Shapiro, William F. Egelhoff Jr., Thomas P. Moffat

Abstract

Electrochemical co-deposition of a series of fcc Ni(subscript x)PT(subscript 1-x) alloys is demonstrated. The alloy composition is a monotonic function of potential. The Pt-rich Ni(subscript x)PT(subscript 1-x) alloys are formed at potentials positive to that required to deposit elemental NI. Co-deposition is ascribed to the negative enthalpy of Ni(subscript x)PT(subscript 1-x) alloy formation that proceeds via a Ni underpotential deposition reaction in concert with Pt deposition. Interestingly, this process occurs at higher Ni underpotentials than anticipated based on extrapolated literature data from thermochemical measurements and ab-initio calculations of alloy formation. In contrast, Ni rich Ni(subscript x)PT(subscript 1-x) alloys are produced at Ni overpotentials although the films are formed under conditions were pure Ni deposition is otherwise kkinetically hindered. The alloy composition corresponding to the transition from underpotential deposition is a function of the PtCl(subscript 4)/NiCl(subscript 2) electrolyte composition. Films with Ni atomic fraction, x, between 0-0.3 and 0.5-0.95, are bright and specular (grain size

Citation

Journal of the Electrochemical Society

Volume

155

Issue

1

Pub Type

Journals

Citation

Mallett, J. , Svedberg, E. , Bonevich, J. , Shapiro, A. , Egelhoff, W. and Moffat, T. (2007), Compositional Control in Electrodeposited Ni (subscript x) Pt (subscript 1-x) Films, Journal of the Electrochemical Society (Accessed April 26, 2024)