Untersuchung mesoskopischer Strukturen an der Grenzflaeche fest-fluessig

Abstract

Metal clusters have been deposited on metal substrates and characterized with in-situ electrochemical Scanning Tunneling Microscopy (STM). These samples are model electrodes with defined mesoscopic structure and were used to investigate correlation between structure and electrochemical behavior of nanometer sized metal clusters. Different size distribution (1,5-9 nm), mean particle distance (0-50 nm) and chemical composition (Pt, Ru, PtSn and PtRu alloy) have been used. The model electrodes were electrochemically characterized by cyclic voltammetry and by electrooxidation of absorbed CO. Preliminary experiments have been done to use the tip of the in-situ STM as an analytical tool in order to investigate single metal clusters. Hydrogen has been electrochemically developed at Pt clusters and was detected as a current at the STM tip. A summary is given of the theoretical background concerning in-situ STM, metal clusters and their use as model electrodes. The experimental set-up and methods used are described. First the structural and electrochemical properties of the substrates are presented. Flame annealed Au surfaces, Au and Pt single crystal surfaces were used as substrates. It is demonstrated that clean electrochemical conditions can be achieved in the in-situ STM electrochemical cell by monitoring the characteristic single crystal surface voltamogram of Pt(111). Also electrooxidation of adsorbed CO is performed under in-situ STM conditions. (orig.)SIGLEAvailable from TIB Hannover: RA 831(3827) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman