Application to the Influence of Mass Transport in Electrocatalysts

For electrocatalysts we generally define the reaction rate in terms of an electrode polarization equation. The polarization equation describes the transfer of charge from the matrix to the solution. For an electrochemical reaction O + ne R, this can be written in the Butler-Volmcr form1,7 

The problem of diffusion in electrocatalysts is analogous to that of diffusion in heterogeneous catalysis. The assumptions adopted in the model are as follows 

the model of three dimensional electrodes can be simplified into one dimensional, 

A solution-phase reactant will be depleted during the operation of a three-dimensional electrode (electrocatalysts), and diffusion of this species from a reservoir at the face of the electrode represents a loss by concentration difference. 

This process involves a redox reaction obeying the Eq. (41). The rate of reaction per unit volume for species O can be written in the form1 

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