AbstractSurface alloys can form spontaneously during the deposition of one metal onto another, especially in systems with a very large lattice mismatch that do not have bulk counterparts (so-called immiscible systems). Spontaneous surface alloying has been widely studied in Ultra High Vacuum (UHV) systems, but these new materials have not been exploited much in practical applications. Since a high control and scalability make a transfer to real and practical systems viable and versatile, surface alloying in an electrochemical environment is an ideal route to the design of new functional materials.
This work presents an investigation of the surface alloying process during underpotential deposition (UPD) of Pb on Au(111) and Pb on Cu(100) in the absence and presence of strongly adsorbing anions, e.g. chloride or bromide.
The phenomenon of surface alloying has been studied using several electrochemical protocols such as (1) polarisation at fixed potentials in the UPD region and (2) repeated potential cycling over a limited UPD range. By following the changes in electrochemical behaviour, the range of potentials and conditions at which the surface alloys form has been established together with quantification of their composition.
Finally, the structural and compositional changes have been investigated by surface sensitive techniques such as X-ray Photoelectron Spectroscopy (XPS), Ultraviolet Photoelectron Spectroscopy (UPS), Energy-Filtered Photoemission Electron Microscopy (EF-PEEM) and Work Function (WF) mapping.
|Date of Award||21 Jun 2022|
|Supervisor||Natasa Vasiljevic (Supervisor) & Neil A Fox (Supervisor)|