Fuel cell electrocatalysis current density

The intrinsic exchange current density,/ , is not a mere materials constant, but it depends on size distributions of catalyst nanoparticles, their surface structure, as well as surface composition in the case of alloy catalysts like PtRu. In this section, we discuss modeling approaches that highlight particle size effects and the role of surface heterogeneity in fuel cell electrocatalysis. 

The slight mathematical operation, which placed the overpotential in the exponential position and the current density on the line, was not yet normal. It was introduced by Agar, also of Cambridge University, in 1938 [7]. One had to wait 23 years before the connection to the well-known phenomenon of catalysis in chemistry became so obvious that, at last, the right name, electrocatalysis, was used in fuel cell work by Gmbb of the General Electric Company in a 1959 publication [8]. 

Electrocatalysis is a heterogeneous process that involves the adsorption and the chemisorption of reactants or intermediates at the interface. These phenomena are encountered, for example, in fuel cells (FCs) or in organic electrosynthesis. The electrocatalytic activity of a given electrode for a certain reaction may be characterized by the current density at a chosen potential, which is proportional to the specific activity, when referred to the effective active surface. As shown in Figure 21.2, the role of a heterogeneous catalyst is to adsorb the electro-reactive species (reactant and intermediate) and transform it to another compound that can more readily undergo the desired... 

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