COMPARISON OF ELECTROCATALYTIC ACTIVITY OF SMOOTH AND PLATINIZED PLATINUM-ELECTRODES - THE SIZE-EFFECT APPROACH

Electrochemical behavior of S2O82- anion in alkaline media on smooth and platinized Pt electrodes with a roughness factor R(f) less-than-or-equal-to 590 was studied. The S2O82- anion was shown not to form a product strongly chemisorbed on platinum in the studied solutions. With increasing R(f), the specific rate of S2O82- reduction decreased by almost two orders. We analysed the R(f)-dependence of the specific rate of electrode processes for the case, in which the process on small (and imperfect) particles is slower than on large particles and compact platinum. To do this we used two simple models of platinum deposit that provide for the occurrence of particles with particular properties, including particles of different size. Experimental data on S2O82- reduction on the Pt/Pt-electrode does not contradict the hypothesis of a size effect.