The Effect of Dislocations and Orientation on the Electrical Double Layer Capacity of Silver Surfaces

Abstract

This study was undertaken in an attempt to obtain a better understanding of the effects of dislocations, crystal orientation, and surface imperfections on the catalytic activity of metals. Relative surface areas of pure silver crystals were determined from measurements of double layer capacities for {110}, {111}, and {211} planes with dislocation densities ranging from 106 to 108 cm−2. Care was taken to insure that clean, oxide‐free surfaces were used during measurements. Although it was found that the relative areas of {110} and {211} planes were proportional to the log of dislocation density, the relative area of {111} planes was found to be independent of dislocation density. The behavior of the double layer capacity as influenced by abrasion, cracks, notches, grain boundaries, and dislocations is discussed in terms of changes in physical area and changes in effective area resulting from additional dislocations. Models of metal surfaces and knowledge about the structure of the double layer are inadequate, at present, to allow positive conclusions to be drawn about the effect of dislocations on double layer capacity. The double layer capacity of mercury in was experimentally determined to be which agrees favorably with values reported recently.