SURFACE-ANALYSIS AND ELECTROCHEMISTRY OF MOS2 THIN-FILMS PREPARED BY INTERCALATION-EXFOLIATION TECHNIQUES

MoS2 thin films of ca 390 angstrom on a TiO2/Ti substrate, prepared by an intercalation-exfoliation method, have been characterized by elect ron spectroscopy for chemical analysis, Rutherford backscattering spec troscopy, scanning electron microscopy, x-ray fluorescence, and electr ochemical methods. Scanning electron micrograph analyses indicates the presence of two surfaces, one composed of basal planes and another of axial planes. Cyclic voltametry of ferrocene, tetracyanoquinodimethan e, chloranil, tetramethylphenylenediamine, and decamethylferrocene wit h MoS2 thin film electrodes without illumination showed linear diffusi on cyclic voltammetric waves. This is due to the metallic-like behavio ur of the MoS2 thin film which have a high density of axial planes on the electrode surface. Under illumination, the cyclic voltammetric wav es of the redox systems had a sigmoidal shape, characteristic of semic onducting surfaces. The electrochemical behavior of the MoS2 electrode , without illumination, is compared to that of an ultramicroelectode ( UME) array. In this case the UME is a MoS2 axial plane site, and it is within MoS2 basal planes (i.e., semiconducting surfaces).