THEORETICAL-STUDIES ON ELECTROCOMPRESSION OF ELECTRODEPOSITED HALIDE MONOLAYER ON AU(111) SURFACE

A simple physical model and theory have been proposed to investigate t he electrocompression behavior of electrodeposited halide (chloride, b romide, and iodide) monolayer at the Au(111) electrode surface. By est ablishing the statistical thermodynamic formulas, the effective pair i nteraction energy, 2D spreading pressure, 2D isothermal compressibilit y, and electrode potential-coverage (theta-E) curves of halide monolay er at Au(111) surface have been calculated. The theoretical results ar e in good agreement with the experimental measurements, which show tha t the adatom-adatom interactions, especially repulsive interactions, d etermine the size of the compressibility in the halide adlayer on Au(1 11) surface with an increase in the electrode potential. The electroso rption valency gamma of halide also plays an important role on the ele ctrocompression. The theory in this paper is in principle applicable t o other anion species at metal electrode surface.