A Comparative Study of the Electrodeposition of Nanoporous Ir and Pt Thin Films

Abstract

This work compares the properties of thin, porous Ir and Pt films, formed by electrodeposition (ED) from solutions containing their respective chloro-complexes, in preparation for the future co-electrodeposition of thin Pt-Ir alloy films for electrocatalytic applications. ED was carried out on Au using potentiodynamic and potentiostatic methods with simultaneous in situ mass measurements, using the quartz crystal microbalance technique. While Ir ED is found to depend on the ED potential in a more complex manner than does Pt, the specific surface area (SSA) of both metal films increases linearly with potential, but decreases with increasing solution concentration. All of the films were found to be highly porous, as confirmed using field emission scanning electron microscopy. The optimum conditions for Ir ED (0.2 V vs. RHE and a precursor concentration of < 0.05 mM) were found to be very suitable for Pt ED as well, giving films 1 to 5 nm in thickness, 25% in porosity, and exhibiting an ED charge efficiency of 75-95%. © 2013 The Electrochemical Society. All rights reserved.