In-situ STM characterisation of the surface morphology of platinum single crystal electrodes as a function of their preparation

A systematic study of the surface morphology of Pt(111) and Pt(100) electro des as prepared by flame-annealing and cooling in different atmospheres (ai r, N-2, H-2 + N-2 and CO + N-2) is presented. The electrodes were character ised by cyclic voltammetry and in-situ STM in 0.1 M H2SO4. Preliminary volt ammetric results for Pt(110) are also shown. In this case, Cu upd served as a structure sensitive probe. It was observed that the presence of oxygen d uring cooling induces surface defects and leads to rough surfaces. Cooling in pure Nz preserves the reconstructed Pt(100) and Pt(110) surfaces, while cooling in H-2 + N-2 or CO + N-2 lifts the reconstruction. The use of CO as the cooling gas turned out to be advantageous for the preparation of clean and well-ordered (1 x 1)-surfaces. The stability of reconstructed Pt surfa ces in an electrochemical environment is discussed. For H-2 + N-2-cooled Pt electrodes, a clear influence of the H-2-concentration on the surface morp hology was observed. (C) 2000 Elsevier Science S.A. All rights reserved.