Processing, Activity and Microstructure of Oxygen Evolution Anodes Prepared by a Dry and Direct Deposition Technique

Abstract

Thin films of RuxIr1-xO2-y have been deposited by a dry combustion process directly onto polypropylene and quartz coupons for characterization and on a gold disk to evaluate the electrochemical suitability as an oxygen evolution electrode. Compositional analysis on the oxygen evolution catalyst suggests a chemical formula of Ru0.41Ir0.59O2-y. Bulk diffraction of the thin film Ru0.41Ir0.59O2-y suggests phases of IrO2 and RuO2 and to a lesser extent Ru metal with no Ir metal. The photoelectron emission spectrum of the film suggests that Ru exists primarily in the oxidized state. The integrated area of the Ir metal peaks is an order of magnitude larger than the RuO2 peaks and 6 times larger than the corresponding oxide suggesting a surface enriched in Ir metal in contrast to the diffraction findings. An exceptional oxygen evolution current of 25-40 mA/cm2 was observed for a Ru0.41Ir0.59O2-y thin film supported on a gold rotating disk electrode in a 0.5 M H2SO4 electrolyte measured at a potential of 1.6 V. The corresponding mass activity of the electrode is exceptionally high at 400 mA/mg of Ru0.5Ir0.5O2 compared to 50-75 mA/mg of Ru0.5Ir0.5O2 from the literature.