Template-Assisted Growth of Ultrathin Single-Crystalline IrO2(110) Films on RuO2(110)/Ru(0001) and Its Thermal Stability

A template-assisted growth of a flat, covering, and single-crystalline IrO2(110) film with controlled film thickness is reported that is suitable for use in model catalysis and as model electrodes in electrocatalysis. The template consists of a single-crystalline covering RuO2(110) layer grown on Ru(0001). In the first step, we formed IrO2 seeds on the RuO2(110) layer, which then continue to grow by deposition of Ir in an oxygen atmosphere of 3 X 10(-7) mbar at a sample temperature of 700 K. The IrO2 seeds are prepared by depositing nanometer size metallic Jr particles on RuO2(110) (in total 0.3-0.5 monolayer (ML) of Ir) at room temperature. Subsequently, the Ir particles are oxidized in 10(-5) mbar of O-2 at a sample temperature of 700 K. The techniques of scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy, and low-energy electron diffraction (LEED) are employed to characterize the morphology, crystallinity, and electronic structure of the prepared ultrathin IrO2(110) films. Thermal desorption spectroscopy, LEED, and STM provide conclusive evidence that the thermal decomposition of IrO2(110) films already started at 500 K under ultrahigh vacuum conditions.