Heterogeneous catalysis in solution. Part 17.—Kinetics of oxidation–reduction reaction catalysed by electron transfer through the solid: an electrochemical treatment

A quantitative expression is derived for the catalytic effect of electron-conducting catalysts on redox reactions by using an electrochemical model. In this the catalyst takes up the mixture potential (Emix) imposed on it by the interacting redox couples; from the equations of their individual current against voltage curves it is then possible to calculate the equal anodic and cathodic currents at Emix. These currents lead directly to the catalytic rate. If both current against voltage curves around Emix are in the Tafel region, the catalytic rate is proportional to the concentrations of the two reactants raised to fractional powers. If the curve of one of the reagents is in the limiting current region, the catalytic rate will be proportional to the concentration of that reagent alone.