The Required Quantity of Active Substance

Finally, the required quantity of catalyst for the activation of an inert substrate can now be estimated as follows. The volume of hemispherical microelectrode, Vm, is given by 

Equation (57) is valid for the cathodic processes. In similar way, the corresponding equation for the anodic ones can be derived. 

It is obvious from (57) that the quantity of catalyst in the form of small hemispherical grain required to transform an inert electrode into an active one decreases rapidly with decrease in size of the particles, for one and the same Sw, as well as with the increase of the 

The current density on the graphite electrode partially covered with silver grains obtained from the nitrate solution by a pulse of an overpotential of 100 mV for 20 ms and by further growth at an overpotential of 40 mV for 30 s (Fig. 14a) is practically the same as the current density on a massive silver electrode at an overpotential of 40 mV The same occurs with a graphite electrode covered with silver grains by a pulse of an overpotential of 500 mV for 5 ms and by further growth at an overpotential of 40 mV for 5 s (Fig. 14b). It can be seen that the deposits depicted in Fig. 14a and this in Fig. 14b, 

It seems to be practically identical with the deposit shown in Fig. 14a, which can also be concluded from calculated x/2rm values, being 2.5 for the deposit shown in Fig. 14a and 2.9 for that shown in Fig. 14b. It is obvious that despite the grains being many times smaller, their mutual relations are similar to those shown in Fig. 14a, producing the same activity with a many times lower quantity of electrodeposited metal, which is in the accordance with (37) and (38). 

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