Electrochemical characterization of irreversibly adsorbed tellurium monolayers on Au substrate and examination of the effect of tellurium adsorbates on the underpotential deposition of tellurium on Au substrate have been performed in this paper. The mechanism of Te underpotential deposition has also been studied. The results show that the tellurium adsorbates could be irreversibly adsorbed upon the Au substrate surface under the open-circuit conditions. Subsequent removal of the Te adsorbates was also proved to be very difficult within the Au double-layer region, and a standard electrochemical cleaning procedure was necessary to remove the Te adsorbates completely. When the potential was cycled into the Au oxidation region, a substantial loss of Te adsobates was observed, which occurred simultaneously with the Au oxidation features. The scan rate analysis of Te underpotential deposition on Au was fulfilled, which agreed well with the model developed by Sanchez-Maestre, and verified that Te underpotential deposition onto Au could proceed by a two-dimensional nucleation and growth mechanism.

Key words: electrochemical atomic layer epitaxy, underpotential deposition, irreversible adsorption, cyclic voltammetry, thermoelectric material