Determination of the morphology of surface groups formed and PVDF-binder materials dispersed on graphite composite electrodes in terms of fractal geometry

Abstract

Morphological structures of surface groups formed and poly-vinylidene fluoride (PVDF)-binder materials dispersed on the PVDF-bonded graphite composite electrode were investigated in terms of fractal geometry using cyclic voltammetry combined with Kelvin probe force microscopy (KFM). When a fractal surface has single fractal geometry consisting of binder materials only, the overall fractal dimension was determined to be 1.82 from cyclic voltammetry based upon the peak current-scan rate relation, which is just the same in value as the individual fractal dimension of binder materials determined from KFM based upon the perimeter-area relation. By contrast, when a fractal surface has multifractal geometry composed of surface groups and binder materials, the overall fractal dimension was determined to be 1.77 from cyclic voltammetry. But the individual fractal dimensions were determined from KFM to distinguish the fractal. dimension (1.70) of surface groups from that fractal dimension (1.82) of binder materials. The overall fractal dimension determined from cyclic voltammetry is just the average of the two individual fractal dimensions determined from KFM. (C) 2003 Elsevier B.V. All rights reserved.