Electrochemical scanning tunneling microscope study of irreversibly adsorbed Te on a Pt(111) single crystal electrode surface

Abstract

Atomic STM images of the irreversibly adsorbed oxygenated Te layer and its reduced layer on Pt(111) are presented. On the oxygenated Te layer, an atomic image with an apparent ( 2 × 2 ) ( α=80°) unit cell was observed, which was interpreted to be a (2× 3 ) rectangular structure containing one Te atom and one O atom, i.e. θ Te=0.25 and θ O=0.25. This structural information, combined with the voltammetric charge (244±2.4 μC cm −2) concerning the redox process of the adsorbed Te layer, led to the conclusion that the chemical unit of the oxygenated Te layer is TeO 2+. The reduced layer of Te on Pt(111) was observed to show two different structures of elemental Te: the (2×2) and (11×8) structures. The observed elemental Te structures differed from those anticipated from the (2× 3 ) rectangular structure of the oxygenated Te layer, implying the movement of the Te atom during reduction of the oxygenated layer. It is concluded that the elemental Te atoms move laterally to form the (2×2) ( θ Te=0.25) and (11×8) ( θ Te=0.284) structures.