Ta Surface Chemistry in Aqueous Solutions and the Possible Formation of TaTe₂and TaS₃

Abstract

This report discusses the reductive removal of Ta oxide electrochemically 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 potentials negative of −1.5 V, the more surface oxide that was reduced, as evidenced by increases in hydrogen evolution. Atomically-resolved EC-STM images were obtained after reduction at −1.8 V. The efficacy of Te at passivating Ta surfaces was investigated and found to work well, from EC-STM, CVs and XPS. S and Cu were also deposited onto Ta following an oxide reduction step. EC-STM images of the Ta surface in HTeO 2 + and Na 2 S solutions suggested the formation of TaTe 2 and TaS 3 , respectively, on the surface.

Selective Electrodeposition of Tantalum(V) Oxide Electrodes

“…This observation readily implies that at more negative potentials the Ta in the electrodeposited film was reduced, which results in the formation of Ta suboxides with lower oxidation states of Ta. This is further consistent with the previous study by Stickney and co-workers where they showed that the surface oxide layer on the tantalum foil can be reduced in aqueous solutions at potentials below −1.5 V . Thus, electrodeposition was performed at −1 V vs Ag/AgCl.…”

Microwave‐Assisted Synthesis of Few‐Layered TaTe2 and Its Application as Supercapacitor

“…Their crystals can exhibit ionic, covalent, and metallic bonding interactions. [26][27][28][29][30][31] In particular, the relatively low electronegativity of tellurium in transition metal tellurides frequently leads to complex competition between metals and nonmetals for the valence electrons and, as a consequence, to valence electron localizations. It is interesting to note that TaTe 2 has been reported to have a distorted 1T structure with space group C2/m.…”