Tellurium underpotential deposited ad-atoms on Au electrodes: A new electrodeposition mechanism using an electrochemical quartz crystal nanobalance

Interfacial phenomena involved in the underpotential deposition of tellurium layers were studied with an electrochemical quartz crystal nanobalance (EQCN) in perchloric acid solution (pH = 1). The in situ study of the oxidation kinetics showed that the oxidation of the Te layer deposited neighbor a Teads/Au provides evidence of TeO2ads formation with the incorporation of oxygen to induce the formation of H2TeO3. From the calculations of the first tellurium layer (82 ng cm−2), the mass expected for the second layer deposited in underpotential control was found. Moreover, the oxidation of Teads followed a bi-functional mechanism involving the oxygen incorporated before the tellurium oxidation at high overpotentials. The combination of powerful interfacial methods (cyclic voltammetry and EQCN) gives a new perspective on tellurium electrodeposition and leads to a comprehensive understanding of the interfacial architecture.