Surface roughness of bismuth, antimony and cadmium electrodes

Abstract

Electric double layer properties of variously treated Bi, Sb and Cd electrodes were studied in terms of the Debye length dependent roughness theory, recently developed by Daikhin et al. The geometrical roughness factor, root mean square departure of the surface from flatness, height of surface roughness and the medium lateral correlation length values have been obtained. According to the experimental data and results of theoretical simulation the surface roughness rises in the order of Bi electrodes: electrochemically polished single crystal Bi(111) plane<cut at the temperature of liquid nitrogen Bi(111) plane<Bi solid drop electrode with additionally remelted surface<cut at the room temperature Bi(111) plane<electrochemically etched Bi(111) plane<chemically etched Bi(111) plane. This order of the electrode surface roughness was in agreement with the ex situ AFM data. At small electrolyte concentrations ( c el≤0.01 M) the deviation of experimental roughness function–inverse Debye length curves from the theoretically simulated ones has been observed, explained by the influence of energetic inhomogeneity of polycrystalline surfaces on the non-equal surface charge density at various homogeneous regions, exposed at the macro-polycrystalline electrode surface.