Preliminary Investigations of Ta Surface Chemistry in Aqueous Solutions of TeO_2, and the Possible Formation of TaTe_2

摘要

Reductive removal of Ta oxide electrochemically was studied using Cyclic Voltammetry (CV), in-situ electrochemical scanning tunneling microscopy (EC-STM), and X-ray photoelectron spectroscopy (XPS). From CVs, it was shown that the longer a Ta electrode was maintained at negative potentials in excess of-1.5 V, the more surface oxide was reduced, as evidenced by increases in hydrogen evolution. Atomically-resolved EC-STM images were obtained after reduction at -1.8 V, and then imaging at -1.0 V. The efficacy of using Te to passivate the Ta surface was also investigated, and Te appeared to suppress oxide formation, as evidenced by EC-STM, CVs and XPS. Images of the Ta surface in a TeO_2 solution suggested the formation of TaTe_2 at the surface.