Scanning tunneling microscopy and electrochemical study of the surface structure of Pt(10,10,9) and Pt(11,10,10) electrodes prepared under different cooling conditions

The effect of three surface electrochemical preparation techniques for single crystal surfaces on two platinum stepped surfaces [Pt(10,10,9) and Pt(11,10,10)] has been investigated by scanning tunneling microscopy and cyclic voltammetry. The preparation techniques consisted of a thermal treatment followed by a cooling step in (a) a hydrogen+argon atmosphere, (b) air (c) iodine vapor+air. For Pt(10,10,9) and Pt(11,10,10) surfaces, the hydrogen+argon treatment provides surfaces that have a very narrow distribution of terrace widths around the nominal value and monatomic steps. On the other hand, facetted surfaces with terrace widths and steps four to five times their nominal values are obtained when the cooling is in the presence of iodine vapor. The air treatment generates surfaces in which the terrace width is not as uniform as in the H-2+Ar case and some kink sites are created. The changes in the surface topography can be followed in the voltammetric profile of the surfaces recorded in a sulfuric acid solution. (C) 1999 Elsevier Science B.V. All rights reserved.