2007 Volume 56 Issue 11 Pages 497-504
Surface stress and surface tension are important parameters for surface energetics of metal electrode. At first, the difference and relation between surface stress and surface tension were explained briefly and then, the bending beam method (BBM) was introduced as a powerful tool for measurement of the changes in surface stress of metal electrode in aqueous solution.
The results of changes in surface stress obtained by BBM for the Pt and Au electrode surfaces oriented mainly to the (111) plane were exampled and discussed from the viewpoint of surface energetics. The surface stress of the Pt (111) electrode changed to the compressive direction during OH adsorption prior to the formation of PtOH monolayer. Particularly, the derivative of surface stress with electrode potential took a maximum, which was explained by the increase in compressive surface elastic strain due to strong bond of adsorbed OH with substrate Pt atom, inducing the surface charge density resulted in the major contribution to the maximum. The similar behavior of the change in surface stress for the Au (111) electrode in aqueous solution containing iodide ions was observed during iodine adsorption prior to the formation of AuI monolayer and was explained by the same manner as those of the Pt electrode.
Moreover, the two dimensional isothermal compressibility of the iodine adlayer or the underpotentially deposited Pb monolayer on Au (111) electrode was evaluated by connecting the changes in compressive surface stress with the changes in the nearest neighbor distance between adatoms obtained from surface X-ray scattering.
