Surface Analysis and Electrochemistry of MoS2 Thin Films Prepared by Intercalation‐Exfoliation Techniques

MoS 2 thin films of ca . 390 Å on a TiO 2 / Ti substrate, prepared by an intercalation‐exfoliation method, have been characterized by electron spectroscopy for chemical analysis, Rutherford backscattering spectroscopy, scanning electron microscopy, x‐ray fluorescence, and electrochemical methods. Scanning electron micrograph analyses indicates the presence of two surfaces, one composed of basal planes and another of axial planes. Cyclic voltammetry of ferrocene, tetracyanoquinodimethane, chloranil, tetramethylphenylenediamine, and decamethylferrocene with MoS 2 thin film electrodes without illumination showed linear diffusion cyclic voltammetric waves. This is due to the metallic‐like behavior of the MoS 2 thin film which have a high density of axial planes on the electrode surface. Under illumination, the cyclic voltammetric waves of the redox systems had a sigmoidal shape, characteristic of semiconducting surfaces. The electrochemical behavior of the MoS 2 electrode, without illumination, is compared to that of an ultramicroelectrode (UME) array. In this case the UME is a MoS 2 axial plane site, and it is within MoS 2 basal planes ( i.e. , semiconducting surfaces).