Effects of anions on the underpotential deposition behavior of Cu on polycrystalline Pt.

ABSTRACT: The process of Cu underpotential deposition (UPD) on polycrystalline Pt (pc Pt) has been investigated by cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy techniques using (bi)sulfate and perchlorate (with/without the addition of a small amount of NaCl) as supporting electrolytes, respectively. The results showed that the adsorption capacity of the anions influences both the reversibility and charge transfer resistance (R _ct) of Cu UPD reactions on pc Pt. With a negative shift of the applied potential, R _ct of the (bi)sulfate system decreases monotonously, whereas R _ct of the perchlorate system (with/without Cl^- ions) decreases at first and then increases. Cu UPD on pc Pt follows Langmuir-type adsorption and two-dimensional nucleation/growth mechanisms. The specific adsorption anions ((bi)sulfate and chloride ions) can not only enhance the Cu UPD process by decreasing R _ct, but also favor instantaneous 2D nucleation and subsequent grain growth. Finally, the possible deposition mechanisms of the Cu UPD process in the presence of specific adsorption anions were proposed.

SUBMITTER: Liu J 

PROVIDER: S-EPMC9080622 | biostudies-literature | 2018 May

REPOSITORIES: biostudies-literature