Pt(111) thin-layer electrodes on α-Al2O3(0001): Morphology and atomic structure

Pt films with a thickness of 3 to 15 nm were grown by vapor deposition on atomically smooth α-Al2O3(0001) single-crystal surfaces and characterized by scanning tunneling microscopy (STM), atomic force microscopy, cyclic voltammetry, Auger electron spectroscopy and Fourier transform infrared spectroscopy. Iodine adsorption was used to directly verify the (111) surface structure of our Pt films: STM images of ordered iodine adlayers revealed the same ( 4 × 3 3 ) superstructure on the films as observed on the (111) surface of a Pt single crystal. The effects of deposition temperature and film thickness on the surface morphology of the Pt films on α-Al2O3(0001) were investigated. The electrochemical characterization of our thin-film electrodes includes a comparison with voltammograms of well-oriented and stepped Pt(111) surfaces.