Adsorption on metal electrodes: examples

Abstract

The adsorption of halides on single crystal metals is a paradigmatic example of the competition between the interactions adsorbate – substrate and adsorbate – adsorbate. Because of their weak solvation shells, anions adsorb easily on metal surfaces, particularly at potentials positive of the pzc. However, it is not easy to determine the coverage. Often the adsorbed ions carry a partial charge, they repel each other, and the coverage increases only slowly with increasing electrode potential. This makes it difficult to determine the coverage by measuring the charge that flows during a potential sweep or an adsorption transient. In systems where the adsorbed anions form a regular lattice, the structure can be elucidated by local probe techniques such as the scanning tunneling microscope (STM), or X-ray scattering and spectroscopy using synchrotron radiation, which allow direct studies of the electrochemical interface on the atomic and nanometer scale.