In-situ observations of adsorption and film formation on metal electrodes by synchrotron far infrared reflectance spectroscopy.
Adsorption and film formation are key processes associated with the passivation and inhibition of metallic corrosion. New experimental approaches are needed to advance our knowledge in these areas. We have developed the technique of Synchrotron Far Infrared Reflectance Spectroscopy (SFIRS) for in situ investigations of the structure and composition of surface films and adsorbed layers on metals. We demonstrate its application to the determination of the nature of surface films on copper in aqueous solutions and the adsorption of anions on gold. The anodic corrosion films on copper in alkaline solution were found to consist of Cu{sub 2}O in the passive region at about {minus}0.05 V vs SCE and CUO, together with CU(OH){sub 2}, at 0.30 V. We have also observed for the first time the adsorption of anions at monolayer coverage on the surface of a gold electrode in perchloric acid solution. Halides (Cl-, Br-), nitrate, sulfate, and phosphate have been studied. When two different anions are present in solution, the more strongly adsorbed species determines the corrosion behavior of the metal. This is illustrated in the competitive adsorption of bromide and phosphate on gold.
- Research Organization:
- Argonne National Lab., IL (US)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 11817
- Report Number(s):
- ANL/CMT/CP-99057
- Country of Publication:
- United States
- Language:
- English
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Synchrotron far infrared spectroscopy of surface films on a copper electrode in aqueous solutions.
"In-situ" synchrotron far infrared spectroscopy of surface films on a copper electrode in aqueous solutions.