FRACTAL DIMENSION OF PLATINUM PARTICLES DISPERSED IN HIGHLY POROUS CARBONIZED POLYACRYLONITRILE MICROCELLULAR FOAM

A new fuel-cell electrocatalyst based on highly porous carbonized poly acrylonitrile (PAN) microcellular foam with platinum particles was pre pared recently in this laboratory. Its surface morphology one of the m ost important aspects of a practical electrocatalyst. has been examine d in terms of fractal theory and methods. The fractal dimension of the platinum particles dispersed in porous carbonized PAN foam was determ ined by using chronometric and rotating-disk-electrode methods in oxyg en-saturated solutions. A fractal dimension smaller than 2 was obtaine d, which was attributed to the partially active nature of the surface of this electrocatalytic material. This value of fractal dimension is also proposed to be considered as a reaction dimension. A reaction dim ension smaller than 2 may indicate that not all of the platinum partic le surface is accessible to the incoming oxygen molecules.